A little backstory on my current issues. It may or may not help with diagnosis...
So I have a set of FCR's that were on my last 96 m900 that was involved in a crash last November. The bike has sat for almost a year now. It's been started a couple times but that's it. Fuel in the bike and the carbs is from a year ago or so at this point.
Yesterday I pulled the FCR's off that bike and installed then on the same model and year new bike.
When I pulled the carbs, I noticed some varnished fuel on the outside bottom of the forward most section of the left carb bowl. I didn't think anything of it
As the bike started and ran fine after the install. I wasn't able to ride it due to weather but I had it running for quite a while with no leaks or smell of fuel.
Today I had a chance to ride the bike. Rode great initially, after about 7-8 mins it started having low to midrange power issues and I smelled fuel when stopped at a light.
I now have fuel dripping from in between the two carbs which looks to be coming from the left side carb above the bowl area. When I pulled he air filter off there was a large amount of vaporized fuel in the throat of the left side carb.
I've done some reading and it seems that the most likely explanation is that the float is stuck. In my research I found some posts about dropping the bowl down without removing the carbs but no real description of what to actually expect once I get in there. I'd rather not pull everything apart again.
Is this the most likely problem, or could it be something else?
Does anyone know of I can simply pull the bowl and everything inside there will stay put, and I can spray everything down safely with carb cleaner or are all the inside contents of the floats, valves, etc going to end up in my hands?
If it is safe to spray down, is there a particular brand of cleaner than best to use with FCR's?
Sorry for the long winded post but I wanted to give as much info as possible.
Yep, most likely a stuck float due to debris or sticky muck.
FCR's are a bit finicky that way.
A bit aggravating to get a bowl off in situ, but doable.
I'd try removing the big plug on the bottom of the bowl and turn the fuel on and see if it'll wash the debris out.
Thanks. Will I need any sort of replacement gasket or something if I do that? Do you know if I can just remove the bowl itself and the internals will stay mounted?
Try Speeddog's suggestion first as the drain nut has an o-ring. Catch the fuel with a cup under the carb when you turn on the fuel tap. Hopefully the float needle is washed clean. The float bowl will also have an o-ring and they are quite sturdy but try the fuel flush first. When replacing the nut/cap/plug, dont over torque it but make it snug.
Then when you turn the fuel back on give the float bowl a tap with the back of a screw driver to seat the float valve. Its toilet cistern tech in there. Do a search here on carb flooding, there is a wealth of info.
Make sure you are using fresh fuel.
+1 on koko`s advice, been there, done that.
I just remembered, the overflow tube exits between the carbs and needs a hose safely routed away from the motor. Does it have a drain hose?
Hmm...no hose in there. I was wondering about that. Kinda expected there to be an overflow tube to be honest. I'll try draining the bowl in the morning. It's entirely possible that there's some crap that was in the lines which made its way into the carb. Will check tomorrow and report back. Thanks guys!
In addition, check the oil level on the engine.
If you've not installed a manual fuel valve, and the vacuum operated valve is eliminated or stuck open, the FCRs will gladly dump a gallon of gasoline into the sump.
Causing all sorts of mayhem...
Oil level seems normal. Vacuum fuel valve seems good. I drained the carb bowl by removing the bolt and some dirty fuel came out. Put it back to gather and started it up.
No leaks while idling ( but then it didn't leak before when I started it and idled it) so I went for a ride for 15 minutes. Got back and it seemed ok during the ride, but when I stopped and pulled up the air filter there was a haze of fuel vapor inside that carb throat and I felt a little fuel on outside of the left carb between both carbs. I have a feeling. If I'd ridden longer it would've started dripping again :(
Get that hose on the overflow tube. Its most likely leaving fuel on the lhs carb due to the angle on the sidestand. You wont be able flush it unless you disconnect a line and supply fuel to it because of the vacuum tap.
Have a good read of the carb flooding threads via search function and at least give the bowls a rap with the back of a screwdriver at idle as a shadetree method of seating the float needles. Its just like smacking the toilet cistern to shut it up. A manual tap gives you more options on dealing with this issue. With a bike sitting that long, you may need to service the carbs properly. You could drain the carbs and spray up into the bowls with carb cleaner but some carb cleaners are harsh as hell and could damage paint and rubber.
With modern fuels containing additives helpful to EFI but unhelpful to carbs you cant get away with leaving untreated fuel for long periods without expecting to service your carbs.
So it would seem that your initial expectation was correct. The vacuum switching valve for the fuel on off, is not working correctly. I checked on the bike this afternoon and the left carburetor was filled halfway up the carburetor throat. I'm wondering if this is the result of the impact of the bike being hit last year, or if it's the result of it just sitting with fuel in the bowls of the carburetors for almost a year
My crank case is now full of fuel and oil :( I promply drained the oil after disconnecting the fuel supply from the tank. I'm assuming at this point that the heads of the engine are now full of fuel as is everything else apparently.
I thought about the carb cleaner option, but I was very hesitant to try that due to its harshness and the expectation that it would likely destroy the rubber O-rings and seals and gaskets in the carburetor.
Unfortunately, I am leaving tomorrow for five days to for a trip. I've drained the oil out of the engine, do I have to worry about any damage occurring due to the fact that there might be residual fuel in the crankcase? I don't have time to properly drain,fill and flush the crankcase with fresh oil before I leave.
How complicated is it to clean out this carb? I was thinking id try to remove the bowl with the carb on the bike as there is plenty of room, but I'm in very unfamiliar territory at this point. I work with my hands on a daily basis and routinely take apart porsche ferrari, mercedes bmw, etc to install built in radar detection systems, so Im familiar with finesse, I just don't know much of anything about carburetors...
The vacuum petcocks seem to just eventually fail.
I've not seen any particular cause.
Your vertical cylinder is filled with some amount of fuel, so don't crank the motor.
Both horizontal and vertical heads will likely have some gasoline-contaminated fuel in the rocker/cam area.
The gasoline in those areas needs to be removed as well.
I don't think there will be any issues with it sitting until you get back.
Take the oil filter off too and let the case drain, take the plugs out and turn the motor over manually with a crank turning tool or putting it in gear and turning the wheel by hand. Put rags over the plug holes and under/around the bike. I once saw the fuel hit the wall hard when cranked with the starter. It's good to let it dry out if your shed is clean and warm. If you have compressed air blow it out. The front exhaust valve cover should be removed to free the oil there too.
If you are paranoid like me you can run a cheap oil and filter for a few minutes idle and replace it with the good stuff.
Replacing the tap instructions will come up via the search function, but basically you fit an in line tap and blank off the manifold vacuum port. After all that I would run it with an over flow hose and see if the carbs were actually flooding, but they were probably ok. If they occasionally do flood (modern fuels can cause occasional flooding), it is so much easier to deal with when there is a manual tap. The overflow hose is an important safety feature and if your bike runs rough a quick glance down will show the fuel escaping harmlessly to the ground snd not your hot motor. Vacuum fuel taps were meant to be a safety feature in themselves, but when they fail they bypass your carb overflow drainage system and pour raw fuel straight into the motor!
So you think the carbs could be fine after all and the vacuum fuel thingy was just flooding the motor when off? If this is the case, what would cause the issues with excess fuel while running?
How do I remove the fuel from the front cylinder? Would running some cheap oil through the motor with a cheap filter for 3-5 mins then draining it out and replacing with good oil and a new filter?
It may be important or may not be, but I swapped over the carbs and the upgraded fuel pump from the doner bike as well as the fuel vacuum thingy. The doner bike has zero issues prior to being hit.
Both bikes have aftermarket exhaust but I have not swapped the forza cans from the doner bike. Could this be a possible cause of the issues?
Any future flooding after the tap swap will be carb floats not seating. Either from dirt in the fuel or from fuel additives designed to clean injectors congealing or waxing up the float valve! What helps injectors, clags carbs. Often, just turning the manual tap off for 10 seconds then back on can reseat the float valves.
The stock oem style pump is plenty strong. What pump you using? It needs to be a high flow but low pressure pump or you will get flooding from too strong a pump. It would be difficult to tell the cause of flooding without an overflow hose to separate the causes of flooding; one from unseated floats leaking out the hose overflow and the other from fuel poured straight down the manifold bypassing the carb from a faulty vacuum tap.
Just turn the motor over by hand sans plugs and leave the valve cover off to drain. You could take the valve covers off and blow with compressed air down any oil galleries. An oil flush with cheap oil wouldn't hurt but it depends how much things have evaporated off. It's best to do whatever gives you the most peace of mind so your head doesn't mess with you. ;D
Pipes are fine.
Thanks for all the great info.
Where exactly am I supposed to install an overflow hose? I felt up in between the two carbs, and was unable to find any sort of a nipple to put a hose on on either carb. Is there a center nipple for an overflow hose that both carbs share?
I'm not sure what pump is in the bike, it was on the donor bike and running fine with the FCR's prior to the bike being hit. There were no known carb flooding or fuel pressure related issues. I put about 1000 miles on the bike after purchasing it before it got hit and totaled.
Is there a particularly recommended or commonly used fuel tap for this application? I've owned lots of Ducati's but they have all been fuel injected up until this one and the donor bike I'm pulling my parts off of.
There should be a T piece between the carbs above the fuel inlet T piece that you can clamp a hose to and run down safely to the LHS of the bike. The oem pump is a pentagon shape and does a good job.
You got a pic of the carbs and pump?
Ah ok. That would explain why I couldn't find one on the carb itself. I'll do that first chance I get when I get back in town on Monday. I'll take some photos of the carbs and fuel pump as well.
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Do I need to flush the system with the same synthetic 20w50 oil i normally run or can I use cheap conventional oil of the run of the mill 10w40 dino oil?
If no, which is more important, The viscosity or the syn/vs dino?
Also, I found the spot for the overflow hose. I have a quick disconnect on the fuel line at the tank. Can I use that to simulate shutting off the fuel tap to reseat the needle valves?
Run of the mill dino oil is fine for the flush.
You can shut off the fuel any way you want, but it's important to shut the fuel off on FCR's whether you have a manual tap or you disconnect the line. Always shut off the fuel if you trailer the bike.
Thanks for the quick response. Much appreciated [thumbsup]
+1 with DP's comments.
I turn the tap off every night or if parked out of habit. I like an in line fuel tap I can get to while the bike is running. 10 seconds off and back on usually clears flooding while on the run.
Any recommendations of. Where to buy one or which can one in particular works best for this application?
I have seen a tidy looking Motion Pro tap with a round knob and pointer. I think the old oem tap could be cable tied to the frame or bolted to a simple bracket. The oem tap is large enough to easily grab on the run with a knob and pointer. So a local dealer may have old stock. I have had luck at lawn mower shops too.
Someone stateside should know of actual stores in your part of the world. Maybe an email to some of our sponsors.
https://www.motionpro.com/product/12-0036
That's the one [thumbsup]. It's tidy.
Thanks! I just changed the oil filter for a new one and ran two oil flushes through the engine on the new filter. Seemed to run fine, however when I drained the oil it was VERY milky.
It's worth noting that while all of the oil was new ( of various viscosities), it came from containers which have been sitting for quite a while outside in my shed. I'm not sure this mattered or had any effect on the oil coming out that way... It was mostly 5w30 and one quart of Dino 20w50. The bike was run for 3 minutes or so before draining it.
Is it possible this is a normal result from only running the bike for a few minutes and it not reaching operating temperature?
I took a video of the second oil flush draining out:
https://vimeo.com/189866234 (https://vimeo.com/189866234)
Any tips on securing that fuel tap to the bike? Zipties or hose clamps?
Thanks again!
If the hoses are Ziptied to the frame the inline tap should be fine. The oem tap bolts to a frame bracket deleted on later models but the bolt holes on the tap could take Zipties I guess.
Thanks. I ordered one today.
So after 2 quick oil flushes, I let it drain overnight. Today I filled with the correct oil and a new filter and ran it for a bit at idle. Topped it off to the correct level and now I see this: (http://uploads.tapatalk-cdn.com/20161102/82a0d0ae9cefee06239fb584ccb6a856.jpg)
(http://uploads.tapatalk-cdn.com/20161102/255b9b566324cfb43501ab991e3bd8c9.jpg)
It would seem that there is still fuel in the oil. Will this be ok to run the bike or do I need to continue throwing money away doing oil flushes until it's clear? I'm on my 3rd filter now and a lot of $$$ in oil :(
Am I just being paranoid and this is normal condensation in the oil?
I used valvoline full synthetic 20w50 and a new k&n filter
My budget is pretty exhausted at this point...
Thanks. I ordered one today.
So after 2 quick oil flushes, I let it drain overnight. Today I filled with the correct oil and a new filter and ran it for a bit at idle. Topped it off to the correct level and now I see this: (http://uploads.tapatalk-cdn.com/20161102/82a0d0ae9cefee06239fb584ccb6a856.jpg)
(http://uploads.tapatalk-cdn.com/20161102/255b9b566324cfb43501ab991e3bd8c9.jpg)
It would seem that there is still fuel in the oil. Will this be ok to run the bike or do I need to continue throwing money away doing oil flushes until it's clear? I'm on my 3rd filter now and a lot of $$$ in oil :(
My budget is pretty exhausted at this point...
My opinion...you've done your due diligence to remove any fuel. Fuel would not be white. The condensation is fairly normal for a Duc run at idle in cool temps. I'd ride it and if any condensation still remains, just remove the oil fill cap at the end of the ride. Any moisture should evaporate.
I think you're just a bit paranoid due to your fuel issue.
Thanks again for the quick response. Going to take a quick ride now :)
Covering the oil cooler will help warm the oil. Removing the oil filler cap for a few minutes after your ride will help get rid of the moisture.
Well it seems like everything's working as it should. Bike ran good. After a 15 min ride there was a lot of moisture in the sight glass so I rode for another 30 mins or so and there was very little moisture left.
Pulling open the fuel quick disconnect for 15-20 seconds while it was warmed up and running seemed to fix the carb flooding while riding issue though I forgot to check the carb throat to see if there was any vaporized fuel in there. Probably too late at this point since it was like an hour ago. Have to check it next time I ride.
Thanks for all the help and the quick responses! You guys are the best! :)
Are you running the oem breather hose to the airbox? I cant remember. Running a little breather pod off the breather box under the seat lets steam escape from the oil vapor leaving less moisture to drain back down to the crankcase.
I agree with making an oil cooler cover for winter. The cooler is quite effective and these motors do a good job of shedding heat, considering they are air/oil cooled. These style motors have won Dakar races.
I've learned heaps here.
It isn't exactly winter in CT yet... [laugh], but an oil cooler cover is a good idea to allow oil temps to rise enough to boil off water in the crankcase if the ambient temp while riding is around 400F.
Idling in the garage will create lots of condensation even above 40.
I bet it would feel like winter to me. ;D
Ha! No not winter yet :) There is a small k&n filter on the crankcase and the breather port is blocked off on the stock air box. I didn't know it would be a good idea to cover the oil cooler. I ride in all sorts of weather.
For what its worth, I had more trouble starting this bike with the stock carbs in the cooler weather than I ever did with the FCR's on the other bike. It's running instantly with the FCR's. No muss, no fuss.
I'm looking forward to installing my fuel valve tomorrow so I can do some riding this weekend :)
I wish my 96 900 started instantly with the FCR's.
Quote from: ducpainter on November 03, 2016, 07:03:03 PM
I wish my 96 900 started instantly with the FCR's.
You'll get the drill figured out.
Quote from: Speeddog on November 03, 2016, 07:38:18 PM
You'll get the drill figured out.
It
may be me, or it
could be the way Eric jets them down low. He always re-jets FCR's regardless whether they were purchased from ca-cycleworks, or direct from Sudco.
Other than cold start up the things are flawless.
What`s Eric`s choise of low speed jet?
Quote from: greenmonster on November 04, 2016, 07:16:21 AM
What`s Eric`s choise of low speed jet?
I wish I had an answer Gert.
I'll ask him and post up, or maybe he'll stop by and let us know.
I do know that he always jets for driveability, and the thing never has as much as a hiccup.
When I say it's tough to start, i mean that it always will fire on the first, and subsequent attempts, but it doesn't stay running on the first few attempts.
Interested in Eric's take.
The supplied pilot/slow jet is quite large, especially so for 41's. I haven't met one I have't had to change.
So I don't know if this makes any difference in my setup but here's a couple photos of the fuel pump on my bike:(http://uploads.tapatalk-cdn.com/20161104/9a01594336ce993074446567316b2b6d.jpg)
(http://uploads.tapatalk-cdn.com/20161104/abbb64fbf6dc94eccaae86fc3cb59cb5.jpg)
(http://uploads.tapatalk-cdn.com/20161104/f7627cbf14bf6d1552edef773c473766.jpg)
(http://uploads.tapatalk-cdn.com/20161104/802f28b42ef6e0b9441fffeb2d20b438.jpg)
Fwiw, my carbs came from CA cycleworks. When its really cold ( like in the 30's ) it's usually running on the 3rd try. Anything above 45 degrees, it's running on the first start attempt.
That's the Mikuni pump that ca-cycleworks sold. It's a lower volume pump than the OEM.
My bike takes 3+ tries at 50 degrees. Maybe 5 or 6 at 40.
Hmm. Maybe you need the pump I have :) But seriously, why would you want a lower volume pump? I figured it was a higher volume pump to work better with the FCR's.
The OEM pentagon pump is the highest flowing low pressure pump I've come across.
My 01' 750 has the small rectangular pump, think the PO changed it. For the type of riding it is more than enough . I have the Mikuni carbs.
Quote from: ducriderinct on November 04, 2016, 09:18:53 PM
Hmm. Maybe you need the pump I have :) But seriously, why would you want a lower volume pump? I figured it was a higher volume pump to work better with the FCR's.
At one point there was not a good source of quality parts for the OEM pump and the pump you have is relatively inexpensive.
I found that the rebuild kit for the dual outlet Mikuni pump that Sudco lists works fine in the OEM pump, and I rebuilt mine for roughly the same price as the small pump you have. A lot of shops, and owners don't want to rebuild stuff due to labor costs, and that small pump seems adequate.
I don't think you could ever use as much fuel on the street as that little pump delivers. 14l/h is a bunch of fuel.
I still have a good working stock pump. What's the life expectancy on one of them? Would it be worth putting the stock pump back in for any reason? The damn thing is huge and there's not a lot of space in there.
Since the pump is off I recommend you rebuild it. You want a genuine Mikuni kit, here is a source http://sudco.com/Catalog37Digital/index.html#/522/
That pump will supply a big ol'e American V8 with enough fuel so there is a lot of grace. Your rectangular pump is sufficient as long as it is close to 100%. Lasted on my old bike for maybe about three months.
The 002-026 kit is what I used. There's 2 extra gaskets.
Here's what Eric said re: my FCR set up.
"Oh and your pilot is a 60
fuel screw is at 1 turn out. Air fuel warmed up was about 12:1 ish so it is on the rich side when warm."
Starts hard...runs great!
1,5 turns in/up on the idle lever when cold staritng (20C) and a quick throttle pump, starts 1 try, idle jet 60. Maybe 1 turn is just a tad to little?
Exept for first start ofter 6 months winter rest, lotsa fiddling.
In climates that have large temperature swings we have to strike a compromise with carburetors, we cannot all live in Hell like Speeddog [evil]
If you jet the fcr's to start easily in cold temperatures they will be fat when they do warm up, conversely if you jet then to cover that large range of start up and running temps you will have a start up routine. It is normal to have FCR's start and then stall on start up if you use the accelerator pumps as your enrichener, the bike will burn off the excess fuel and lean stall. Usually after you have done this once or twice the engine has some heat in it and will no longer be lean causing the mixture to be correct.
If you jet the pilot jet or fuel screw rich then you are probably fat when at running temperatures. We prefer the bike runs better than it starts but it still needs to start. an ideal setup would be an enrichener circuit or an adjustable fuel screw where you could richen it for starting and then lean it back out when warm. that's not needed most of the time if you have the patience and can follow a start up procedure.
In painters case his pilot went down from a 65 to a 60 and the fuel screw went from 1/2 out to 1 full turn out. Cold start is pretty normal with 1 or 2 stalls before idling and his air fuel is just about 12:1 when warm. If I richened his pilot to a 62 then the fuel screw might go in some to be in the 3.5-5.5 CO range I shoot for BUT when warm he would be rich below 12:1 and over the 5.5 CO. Always a trade off. If our temperatures were higher and stable then we might allow the pilot to be even leaner as there would be less of a swing from cold to hot.
The smaller rectangular pump is not what Ducati used but I have had one on a Bimota DB4 with FCR's and it worked just fine it was oem on that bike.
Quote from: greenmonster on November 05, 2016, 07:08:39 AM
1,5 turns in/up on the idle lever when cold staritng (20C) and a quick throttle pump, starts 1 try, idle jet 60. Maybe 1 turn is just a tad to little?
Exept for first start ofter 6 months winter rest, lotsa fiddling.
My bike sits...
a lot. That could be part of the equation too. When Eric and I went for our ride the thing would be running as soon as I thumbed the button. Started better hot than it ever did with the Mikunis. I drain the bowls, or let the bike run out of fuel after every use because it gets used so little. I also keep stabilized fuel in the tank.
It's time to fog the motor and put it to bed for its winter nap.
Hibernation. ;D
With our fuel down here 60 slow jets foul plugs in '41's. With hi comps when using our 98 RON pump gas with 60 slow jets its like having a choke on. Soon as the motor warms up it stalls. Clearly a result of kangaroo piss additive. The Japanese import Formula 400 racers came with the smallest slow jets avaiable, but that was a rich setting down here.
I have run 50-52 slow jets in '41's and 55-58-60s in '39's for a 900.
My motor is not high comp. Stock 900.
I run 87 octane (R+M/2)
Do have to run e10 fuel in NH?
Quote from: koko64 on November 05, 2016, 02:58:37 PM
Do have to run e10 fuel in NH?
Yup.
There are a couple of stations that sell ethanol free, but they're pretty far.
The moonshine additive leans the mixture out a bit. ;)
Also inhibits atomization at cold temperatures. Steve (ECS) put a couple of gallons of ethanol free in my bike. Big difference.
So more chance of carb freezing?
Freezing should not be more of a problem. Moisture in the air is what freezes.
The other consideration with ethanol free fuel is, generally, it's only available in higher octane ratings. I don't need to carbon up my motor.
I have a steel tank, and if you're careful you can avoid the pitfalls of the ethanol.
So all along I've been thinking that 93 is better for my bike, and that's what I've been using.
Previous owner said he always ran 93, but based on what you just wrote, do you think I should be running 87 instead of the 93?
I'm fairly new to carbureted engines...
Quote from: ducriderinct on November 06, 2016, 07:06:40 AM
So all along I've been thinking that 93 is better for my bike, and that's what I've been using.
Previous owner said he always ran 93, but based on what you just wrote, do you think I should be running 87 instead of the 93?
I'm fairly new to carbureted engines...
About 16 years ago, Bruce Meyers of BCM, told me that the low comp Duc motors were much better off with 87 octane, and more octane was just wasting money, and carboning up the combustion chamber. Higher octane fuel has additives that inhibit combustion to eliminate pinging.
If you have high comps, or a 944 kit with high comps, then continue running the 93. Otherwise, try the 87 and see how it does in your bike. You might also add some Techron to the fuel for several tanks.
Your bike should be fine on 87 with the stock compression ratio. Should be because every specimen is different. 93 is way too high. If your bike does not ping on 87 run that. If it does, move up one grade. The carbon from too high an octane is made worse with the ethanol.
So I have another related question. After all the fantastic help from you guys, I seem to have solved the flooding issue as well as the faulty fuel valve issue. Thank you so much to all that have contributed : )
Now that it's running (fairly) well, it's great around town, low gears partial throttle and full throttle, however, when I get on the highway and try cruising at around 60 to 65 in 6th gear at partial throttle around 4500 RPM, it sputters and pops and hiccups like its flooding or something... If I give it more gas and start accelerating it seems smooth and fine with no issues.
I never noticed any of this behavior when these carbs were on the other bike.
Is there possibly something different about this engine versus the other engine even though they're the same year and model that I need to compensate for somehow? The other bike was run on 93 octane exclusively prior to my purchasing it.
Every engine is different. Some have better ports than others and require different pilot jets, or different fuel screw settings, or different needle positions.
At that road speed in 6th gear you're at a very low throttle opening. I'd try turning the fuel screws in a 1/4 to 1/2 turn and see if it helps. If it gets better try some more until it doesn't get better. If it doesn't go away you might have to play around with needle position, or perhaps a smaller pilot jet.
The circuits in a carburetor overlap so sometimes it takes more than one adjustment.
The air jet in the carb inlet is also a quite powerful adjustment.
AFAIK, all of the recently sold flatslides come with adjustable air jets.
If yours has older fixed size jets, it's definitely worth the money to get the adjustable ones.
It's the one at about 7 O'clock when facing the carb inlet.
The overlap between pilot jet, mixture screw and air jet is ridiculous on the FCR's.
I'm pretty well convinced that it's possible to run three different size pilot jets with associated mixture screw and air jet settings, and have the bike run quite well.
Those of us with dynos and sniffers may be able to slice it fine enough to tell the difference.
Ok. I'll give it a try
With the fuel screws. How exact do I need to be with the turns? It's kinda hard to see them way in there. If I'm a little off left to right will it affect the balance/ drivability?
I'm learning fast on here about these things :)
Buy a tiny screwdriver and mark the handle with a marker pen.
What jets and needle position (again)?
I gave them a quick 1/4 turn and went for a spin.
Didn't make it to the highway yet, but a 1/4 turn in greatly improved the low speed drivability, so hopefully the highway will be a bit better too.
I honestly have no idea on the jetting and clip settings. I bought a bike that had these installed already so I've not been inside them. I know they came from CA-cycleworks.
I've resisted throwing down for a pair of these, at least so far:
https://www.amazon.com/Racing-Products-Flex-Jet-Remote-FLEX-TECH/dp/B005UGFIYC
But my resolve is weakening.
There's also the more standard knob, like this:
https://www.amazon.com/Factory-Effex-17-36030-Adjustment-Screw/dp/B00PUOHE14/ref=pd_lpo_263_tr_t_3?_encoding=UTF8&psc=1&refRID=Z1SJDR27V51PHFYN1WKK
Quote from: ducriderinct on November 07, 2016, 04:26:22 PM
I gave them a quick 1/4 turn and went for a spin.
Didn't make it to the highway yet, but a 1/4 turn in greatly improved the low speed drivability, so hopefully the highway will be a bit better too.
I honestly have no idea on the jetting and clip settings. I bought a bike that had these installed already so I've not been inside them. I know they came from CA-cycleworks.
Show us a spark plug.
Koko, I'll pull one and snap a pic tomorrow.
Speeddog, I'm not really sure how the first ones would work in the available space in there, but the standard knob ones look pretty Intriuging... If I end up doing a lot of fiddling with them it might be worthwhile...
I'd likely do a different bracket for the knob on the flex cable one, put it where it's most handy.
By the time I saw those knobs, I'd gotten my FCR's close enough to right, I just couldn't justify it.
Here's some photos of the horizontal cylinder plug:
(http://uploads.tapatalk-cdn.com/20161108/a6eff34b6349f0fb8883eab44a73738d.jpg)
(http://uploads.tapatalk-cdn.com/20161108/0f06ff8d384782b50db13c001ae9ccfe.jpg)
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Are these pics taken after idling a while?
"however, when I get on the highway and try cruising at around 60 to 65 in 6th gear at partial throttle around 4500 RPM, it sputters and pops and hiccups like its flooding or something..."
When that happends, hit kill switch and take a pic.
Air screw, how many turns out?
I did have it idling for 3-4 minutes or so in the driveway before I put it back in the garage. Does that count? I have no idea on the air screws or any other screw settings.
I don't know what baseline is supposed to be or where anything is currently. Honestly, I'm kinda afraid to touch too much as I really don't know what I'm doing and don't want to take a running bike and make it not run :)
Yes, do what greenmonster says. Do select a safe location to perform this.
Ok. I'll try to do that tomorrow since it looks like I'll have a light day of work.
Screws:
Low speed fuel jet: Bottom of fuel bowl.
Air: Remove air filters, the adjustable at inlet it is.
Just take it slow, one at a time. Make notes.
Screw them in, noticing how many turns.
Probably, sooner or later you'll have to do this,
making sure they in the ballpark and EVEN...
Sooo easy one is a half turn off, we're all been there....
Finally had a chance to take a look again at the fuel screws on the bottom of the carbs. Currently, they're about 3/4 of a turn out after I put them back where they were originally after fiddling with them.
I was starting to see that same hesitation at low speed riding after a while as well once I turned the srcews in a 1/4 turn so I put them back.
This configuration ran perfectly on the other stock motor, so I'm hoping that my adjustments cant be that far off. Is it possible I need to turn them out to compensate for the colder temps leaning out the mixture?
Yes, they may need a 1/4 turn out for the colder temps.
I don't think the FCR's compensate for air density at all, or at least nearly as much as the CV Mikunis do.
Quote from: Speeddog on November 27, 2016, 09:42:16 AM
Yes, they may need a 1/4 turn out for the colder temps.
I don't think the FCR's compensate for air density at all, or at least nearly as much as the CV Mikunis do.
I think you were correct with the 'at all' comment.
So after an hour of riding, and lots and lots of fiddling with the fuel screws, at about 3/4+ an 1/8th of a turn the problem is there but less so than in any other position I could find.
I pulled the horizontal cylinder plug after killing the motor while it was happening and this is what it looked like:
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Not sure if it's related or not, but after being on the throttle partway for some distance, like when riding on the highway at a constant speed, or on surface streets at a constant speed, when I let go of the throttle and pull the clutch in the idle stays very high. I mean I like in the 2 to 3000 RPM range.
This happens when the idle is set at around 1200 RPM when at operating temperature. If I dial the idle back down to around 1000 or just under, the engine drops to idle much more quickly.
With FCR's don't look for a number on idle speed. Just set it so it drops back quickly, and doesn't stall.
It isn't related to the constant speed running issues, if any. That plug looks OK to me.
Hmm, ok. That's good I guess :)
Can the idle being set too high cause this issue? I have a roadracing tach setup and have been going by the numbers...
Maybe it's just set way too high?
I don't think the 'hesitation', as you describe it, is related to the idle speed setting.
I think you said you synched the carbs. Did you use carb sticks to do it?
Ok. No, I have not synced them. They have less than 2k miles on them since new.
Is the idle hang normal for these carbs? I'm starting to think I have some sort of clogged jet somewhere or something...
When the bike gets warm and idle speed is too high you hit the part of the ignition curve where ignition advance gets pretty steep which is probably the cause of the high idle. Idle speed should be set with a real tach. But, since you have FCRs with the idle speed knob, what ducpainter said is a great alternative. Also, as ducpainter said, poor synch can cause that problem.
The idea of going a little rich on the idle screws during the cold weather season is for easier starting and better operation during warm up. Can you describe your present hesitation symptom to us?
Ok, I'll have to look up how to sync the carbs.
As for the hesitation, it's only at a specific part throttle portion close to the idle. As far as exactly where, I can say that it's right before where the FCR's start to make that wonderful sound they make under acceleration. That point where you're off coasting and just giving it enough gas to maintain speed.
The best word I could use to describe it would be sputtering. It never quite falls on its face, but it feels like it's constantly about to. The longer I ride it with the throttle in this position the more obvious the hesitation becomes. As soon as you twist it a little more and get into acceleration, it's goes away.
I have noticed, during my test rides, that the bike feels like it has more power at 3/4 throttle than it does at full throttle. When I'm at full throttle and I back off a little the bike feels like it pulls more.
I most notice it at about 65 miles an hour in sixth gear in about 4500 RPM which is where I tend to cruise on the highway. It's very hard to duplicate at surface street speeds or around town. Other than the inconsistant hanging rpm before returning to idle, it's behaves perfectly around town.
The more i turn out the fuel screws, the longer the rpms seem to hang. Sometimes they don't drop for almost a minute.
Sorry to ask again, but I couldn't find it looking back through the thread; are you running pods, drilled airbox lid, fully open lid, stock airbox lid sans snorkles or stock oem airbox? I'm sure I've missed it somewhere. The intake set up has significant implications for your jetting requirements.
No worries. It's a stock airbox, open lid ( top completely cut off) running a k&n filter. This is the exact setup from the other bike transferred to the new bike along with the carbs and fuel pump.
After doing some more reading, it appears that some people have experienced something along these lines that was remedied by moving the clip on the needle, raising the needle up to richen the mixture. Any thoughts on this?
This entire scenario is so confusing to me because all of these components worked perfectly together on a different engine. Is there that much difference between engines? Same model and year?
There are differences due to parts tolerance stackup, especially relating to cam timing.
I'd close the air screws 1/8 turn and see if that cures it.
I swapped in a set of 'EMS' needles on a customer's hotted-up FCR-equipped 900SS, and it worked well.
Ok thanks. Try main jets in the 160-165 range as there are probably 155s in there as delivered. 155s with a fully open airboxp cam cause you to run out of gas at 3/4+ throttle.
Try 55 or 58 slow fuel jets to stop the low end stumble or open the slow air jet screws a1/4 or 1/8 turn instead. Even 1/16 a turn does something. Speeddog referred to them and they are indeed a strong adjustment.
Your fuel is probably a bit different so locals can advise you you with the fine points but that should give a base for an open airbox. Unfortunately too rich and too lean can give a similar feeling symptom to people when they are starting out tuning.
Sometimes its better to give the job to a good tuner and pick up some overtime instead to pay them. If you have to do it yourself then you need to be able to recognize when you go a step in the wrong direction and what that means. An extra shift is often much less time than doing it yourself.
Speeddog can take it from here
[laugh] Speedog wants to close the air screw and I want to open it. What matters is understandibg the motor's response when you do and reacting appropriately. You see it could be a rich or lean issue down low and we want to test how the bike reacts.
Yeah there's quite a bit of a learning curve here...ill get it eventually : )
Truth be told, As frustrating as it can be, I really am enjoying the learning process and collecting the knowledge of how to dial in carburators. I just wish I had more time to devote to it...
I'll give the airs screws a try the next time I have some free time. I'm running out of usable temperature days unfortunately.
I'm assuming I need to pull the airbox to adjust the air screws as they look to be on top of the carbs if I'm reading the diagrams correctly?
You can just pull off the airbox lid and filter, then access the jet through the hole in the air horn.
You may need to drill the hole in the air horn a bit larger to be able to get a screwdriver in that's big enough to turn the jet.
I didn't have a screwdriver that was appropriate, so I grabbed a short piece of 1/8" welding rod, hammered the end flat, filed it down a bit, and bent about 2" of the other end 90 degrees.
It wasn't optimum, but it's good enough.
If you have a stock airbox lid try the closed lid first. It will richen it up enough for you to get a clue which way to jet/adjust. Ducpainter is correct on the idle hang up, when warm keep lowering the idle until it simply does not hang. If it will not idle at that idle it is telling you something else is wrong, a warmed up motor should idle around 1000 rpms with FCR's, Mikuni's CV carbs wabnt to be about 100 rpm higher.
I would get the bike up to normal temperature and then do a more air/ less air test using your air filter/ airbox lid. Watch for improvements in the area you have the problem now, you are just looking for direction which way to go.
I didn't have a stock airbox that works with the m900 so I decided to take some time today to ride and try to work it out.
Armed with several different screwdrivers and after a bit more fiddling, and more riding, and some more fiddling with the various adjustment screws, I've found a combination seems to work fairly well.
The fuel screws on the bottom are about 1/16 of a turn out from the baseline setting ( I believe it was 3/4 of a turn out), the slow air screws are about an 1/8th of a turn in from wherever they were which I'm assuming was probably stock settings as well.
In 45 degree temps, the problem seems to be solved for the moment. I did have to significantly increase the idle screw setting to get it to stay running however, not sure if that means anything or now.
There is a bit more rpm hang than I'd like and it sometimes hunts a little at idle ( it will dip down a little then come back up here and there, enough that I didn't want to bring the idle down anymore as I thought it might stall) and there's definitely a smell of fuel coming out of the exhaust now when I'm stopped at a light, but at least it's rideable, so I guess I'll have to deal with it for now. Good enough I suppose.
Now that I think about it, I seem to remember my girlfriend complaining that my bike smelled like fuel when she would ride hers behind me last fall, so I guess I'm on the right track... Hopefully the next time I take a ride, she will still be running as well as right now, or I'll be posting back in this thread again looking for more help.
We'll see what happens when the weather warms up. I imagine I'll have to do more tinkering again but at least this time I'll have some idea of what I'm doing thanks to everyone on here who contributed to this thread.
You guys are awesome!
Seems like you richened it up a bit.
Check your plugs after a couple of rides to make sure you aren't going to have a fouling problem.
Yeah I figured. The weird part is, in my mind anyway, that at 1/16th turn out on the fuel screws alone, it got better, but any more than that on the fuel screws alone made it worse then before, however, the combination of both the fuel and the air screws a worked really well...in my mind, both were towards the same goal, richening the mixture; what am I missing in that one way worked and the other didn't?
Do the fuel screws adjust the overall mixture over all throttle positions, while the slow and air screws only richen/lean out the 1/8th- 1/4 throttle area?
Should I return the fuel trim screws back to stock and try that to take away some of the richness, or am I wasting my time ?
I don't know the answer about the fuel screws. I think they only adjust a certain range, but all the jets/adjustment overlap to some extent.
The way I learned was the first jet you need to get right is the main, and work backwards from there.
Quote from: ducpainter on December 02, 2016, 02:31:53 PM
Seems like you richened it up a bit.
Check your plugs after a couple of rides to make sure you aren't going to have a fouling problem.
Yep I agree. Stinky raw fuel smell from riders behind is a sign. I'll say it again, try a smaller slow fuel/pilot or open the slow air screws to compensate if you dont want to touch em. Check those plugs as they will tell you a story.
Your plugs looked rich in the lats pics you`ve posted. Fuel smelly=rich.
"the slow air screws are about an 1/8th of a turn in from wherever they were which I'm assuming was probably stock settings as well."
Do not assume, make sure all is even.
Then, try w air screws 1 full turn out from fully closed, fuel screw 3/4 turn, open lid.
As delivered air screw setting is 1 1/2 turns out from lightly seated according to my CCW and SUDCO notes. 1 turn is a 360 degree turn btw.
From Chris' site:
Fuel screw
mixture screw 3/4 turn
Slow Air Screw 1-1/2 turns
Ok. I'll give that a shot the next time I have a chance to get on the bike.
Greenmonster's suggestion of 1 full turn out on the slow air screws and 3/4 turn out on the bottom carb screws seems to have done the trick! So far she runs great at partial throttle cruising on the highway and when I rev a little at a stop, the idle drops instantly right back down.
Also when I go to start it, I no longer need to mess with the idle knob. A quick pump on the throttle then she's instantly running. I'm hoping it's the screw setting and not that it's been 60+ degrees the last couple times I've ridden, but it seems to be sorted for now :) Thanks for all the help guys... I