The bike is a 1999 carbed M900 with 33,000 miles. A few days ago I was riding on a 92oF day, and the bike bogged way down while climbing a small hill after about an hour of riding. It would restart and idle fine, and sometimes would take full throttle under load, but would ultimately bog down and die within a minute or so.
I check the following on the side of the road:
- Kinked/collapsing fuel lines: all had slight resistance when pinched, and also verified all lines under tank were not kinked
- Gas tank vent: Opened filler cap when running, but no "whoosh" sound
- Vacuum petcock: Removed two years ago
- Battery: Connections loose! I tightened them up and the problem still existed. I checked the battery voltage later on, which was 13.3v which is 90% charge for Shorai lithium
- Electrical connections: All seemed fully engaged, no frayed wires or anything loose. All fuses intact
What is weird is what happened the next day. I replaced the fuel filter since they are cheap, and I have a fuel pump rebuild kit on hand, but not installed yet. With only the new fuel filter installed, the bike started fine but was bogging as before with throttle in neutral. I let the bike idle for about 3 minutes, and tried throttle again....and the bike did not bog! It accepted all throttle after that, but I did not have a chance to ride it. Maybe the fuel line had debris that was dislodged with the revving? I did cut open the old fuel filter and the paper media looked pretty clean.
A ride will confirm that it is better, but if not I am thinking the fuel pump may need rebuilt. Or maybe this was related to the battery being loose, but the issue was not resolved when the terminal connections were tightened up on the side of the road. Let me know what you guys think - thanks!
What do your spark plugs say?
Top of the plug is brown/black with no oil residue. The ground strap is more gray, and the insulator is clean white.
Was thinking about it more last night, and I shouldn't rule out a sticking carb float either.
Since you have the kit, rebuild the pump (unless it is a Winderosa kit, if so, throw it in the garbage.) Go for a nice ride, then report back.
Howie - the fuel pump rebuild kit is a Mikuni MK-DF-62 (http://www.ebay.com/itm/391102520575). I did not rebuild the fuel pump yet, just because I have not had any time.
Went for my ride last night, and he bike seemed to run just fine. I may have detected some exhaust popping on heavy acceleration, but it was very, very faint. I will continue to ride and see what happens since my confidence is pretty low right now.
I am still perplexed on what happened...I will continue to keep an eye on the fuel lines, but the best idea I have is still a clog in the line or a stuck float. If it happens again, I will give the float bowls a good tap just to verify. I am also going to inspect my manual shutoff to make sure no debris has collected in it.
If the carb float needle sticks open you will get a fouled plug on that cylinder and overflow out the carb drain hose if its flooding bad. White porcelain is lean so maybe fuel not getting through. Check both plugs to determine a blockage on one carb or fuel not geing pumped at all.
Does it run better with a full tank? If so suspect fuel delivery.
With your e fuels I would rebuild the pump like howie suggested. Some fuel tap rubbers swell and strangle supply and I have also seen stale fuel goop glue float needles shut.
I was thinking that the floats may be sticking on the low side, so the bowls wouldn't have enough fuel to take full throttle. Is that even possible?
Like both of you have suggested, I will rebuild the fuel pump and report back.
Internal filter on the carb inlet T can get clogged. I pull them out and trust a good in line filter.
Update!
I rebuilt the fuel filter. The old diaphragms were a little worn, but I did not notice any tears. The diaphragms in the rebuild kit are slightly different than the existing ones, but the concept is the same. I went for a nice ride and did not have any problems.
Just for shits and giggles, I checked the plugs after my ride. Like I said - the ground strap is gray, is this normal or indicating lean? Porcelain is not as clean as I originally thought. The top of the plug is more black than brown...maybe I am running a touch rich? Don't mind the silver area opposite the ground strap on the vertical cylinder plug, I accidentally got some anti seize on it.
Horizonal:
(http://i.imgur.com/hjF9fHL.jpg)
(http://i.imgur.com/YfHqPzh.jpg)
Veritcal:
(http://i.imgur.com/gBnLrGr.jpg)
(http://i.imgur.com/05cGGwB.jpg)
Are those pics with a flash? If not the plugs look lean on my little phone screen. Does the light coloured porcelain go all the way to the base? Look down there with a flash light.
Are you running stock jetting with an open airbox? Are there any black dots on the porcelain?
Hopefully someone on a pc/lap top will pitch in. This phone screen is tiny.
On my laptop it looks like just the very end of the insulator is colored.
Maybe a little lean, or not much throttle. hard to say.
Those pictures are in direct sunlight, no flash.
I'm running an open air box with a Factory Pro jet kit (CRB-D12-3.1-TI) and new emulsion tubes (CRZ-EMU-100120k). I also partially cored the stock exhaust. When I installed the jet kit I tried the 150 main, which fouled plugs within a ride, 142.5 was too lean, so I have the 145 installed. What is stock main jet size...140?
Looking at the insulator, only the tip is colored very light tan. The horizontal insulator is white down to the base, and the vertical is white for 2/3 and the base is darker. I do not see any black dots.
I might be installing those 150s again over the winter and giving them another shot.
Factory numbers must be different from Dyno-Jet numbers.
I ran 165's in my Monster with a drilled lid and DP cans.
FP jets line up with oem while DJ run at roughly ten numbers higher for same size oem. So for example, 175 DJ main jets are roughly 165 oem Mikuni jets (or therabouts). ;D
Do the mixture screws only control the mix before the mains pick up? I am thinking of fattening the mix for the time being, since I am only at 3 turns out.
Quote from: Dellikose on September 21, 2015, 09:28:20 AM
Do the mixture screws only control the mix before the mains pick up? I am thinking of fattening the mix for the time being, since I am only at 3 turns out.
Yes, the idle mixture only affects the lower throttle openings.
If you normally ride at low throttle settings I'd give it a try. IIRC my bike was set at 3 1/2-4 turns out.
Thanks DP - I do usually cruise on lower throttle, so that should help me out.
With an open airbox that's fully chopped you need 160 to 165 main jets (Factory Pro or Mikuni), or 170ish to 175 DJ main jets. That jetting relates to V 900 heads, so if your bike has W heads then my experience may not be relevant. Maybe the previous fouling was caused by carb flooding and contaminated your data? I wouldnt want to thrash an air cooled motor showing off white plugs. I would add some fuel.
I would want the plugs more tan or light brown coloured than the pics. These old air cooled motors dont mind an extra dollop of fuel for cooling and response.
Thanks koko. I have the V heads, so I will take your advice and reinstall the 150s at the very least.
I am a bit confused though...Factory Pro has the CRB-D12-3.1-TI kit here (http://www.factorypro.com/Prod_Pages/prodd12.html). Its description states that it is For when you remove the airbox and run individual filters OR no airbox lid. When you add this kit to the cart via PayPal, the description is CRB-D12-3.1-TI,M900,145,147.5,150. Those mains are what I have in my kit, and are much smaller than what you are suggesting. Is Factory Pro not including the correct size jets in their kit?
I have run 155 mains with a drilled airbox, 160-162.5 with pods and 162.5-165 with fully open airbox. Maybe our fuel down here is the difference. Those plugs looked lean except for the porcelain tip. If they are white or cream coloured deep down on the porcelain, then the main jets are too small.
I would buy some sets of main jets. Some have preferred DJ needles with Factory Pro springs. Some are even moving back to oem springs if they have had slide flutter issues. There is room for personal preference with how you want the power to come in at different parts of the rev range. Main jets are cheap enough to try.
Ime 150 jets work with the snorkles removed or the airbox drilled to some extent. Because Im way over here, its hard to account for different fuels. Plugs dont lie, however.
Curious to see how it works out.
This is how my airbox looks...
(https://farm3.staticflickr.com/2832/8972570465_7e93a02d3f_z.jpg)
Ran 165 Dynojet mains,dynojet needles and springs. Mixture screws about 4 turns out.
Always 87 octane.
Regarding ordering new mains, these look to be the correct part: Mikuni N208.099 Press-In Style Main Jet for Ducati and Yamaha BST Carburetors (http://www.power-barn.com/mikuni-n208-099-press-in-style-main-jet-for-ducati-and-yamaha-bst-carburetors/)
I am thinking of getting 160 and 165, based on everyone's option. It's funny, I compared the jets which I removed when I installed the FP jets, and they look larger than the largest jet in the kit (150) but they do not have any markings on them. Pretty stupid of me to miss that, and I guess that the previous owner already bumped up the mains at some point. [roll]
Also - here is a guide I have been using to help me tune the carbs: Carb Worx (http://carbworx.com/Carburation.html)
Do the carbs need to come off to replace the mains, or can I just remove the bowls and get to it that way?
Unfortunately yes (unlike FCRs). It would be very difficult doing it reliably without removing the carbs and flipping them to get at the jets. The main jet retainer can be fiddly to firmly support the jet. You need to clearly see what you are doing. Not impossible but very tricky with carbs in place.
I did my Dyno jet kit with the carbs in place.
It wasn't easy, but it was probably easier than removing them.
Plus, Bruce told me to do it that way. If I got into trouble taking them off the harassment would have been unmerciful. ;D
While we're on the subject of stock vs flatslides, I miss my choke already and it isn't even cold. [bang]
;D Its the throttle cable set up I hate. D at least can remove the pods to get a clear shot from the front of the bike. Put a rag over the front cylinder fins.. ;)
More accel pump squirts needed as the year goes on. I got up to six pumps with up to three starting attempts in our "winter". Im betting 10 pumps and five starting attempts in your Winter. We could run a book on it. :D
Quote from: ducpainter on September 22, 2015, 03:12:36 AM
This is how my airbox looks...
(https://farm3.staticflickr.com/2832/8972570465_7e93a02d3f_z.jpg)
Ran 165 Dynojet mains,dynojet needles and springs. Mixture screws about 4 turns out.
Always 87 octane.
I ran mine for awhile with a similar set up with a drilled airbox. It ran 155 FP main jets which would roughly equate to 165 DJ jets.
Well I borked this pretty good. I was installing the 165s and stripped the bolt that holds the bowl on to the carb. Literally two finger pressure and boom, totally stripped. It's the one that bolts the bottom of the bracket that holds the throttle cables in place. Think it can tapped for one size up?
I hope that that wasn't a $250 screwup. [bang]
http://www.timesert.com/ (http://www.timesert.com/)
Those should be included in the jet kit [thumbsup]
I recently put some little M5 helicoils on an FCR for the float bowl screws. Worked well, but you gotta put them in at the correct depth when you don't have a blind hole to seat them. Over tight float bowl retaining screws are pretty common.
i am no duc expert...absolute noobie actually...but i have been riding vespas for 30 years and those photos of your plugs look like you are running way too lean....
Yes on the lean side. If the tan section was over the whole porcelain it would be better.
I had some quality time yesterday with the carb.
First things first, I mentioned that I stripped one of the float bowl bolt holes. I may have been lucky - the bolt that Factory Pro provided in the kit is too short to go through the throttle cable bracket and the bowl mounting surface. So while I did strip a few threads, there may be enough of a bite with the original, longer bolt. If not, it's Timesert / Helicoil time.
I replaced the jets with 165 Mikuni jets. I had the choice of either 160 or 165, and I chose 165 due to a couple of reasons. First, I measured the jets that were in before I started any of this work, and found them to be around 162.5. The way I measured was to place them on a 1.5 mm allen key and see how much slop each jet had. Second, and the most important, was based on the experiences of the commenters in this thread. [beer]
I did notice a bit of corrosion between the float bowls and the carb body, along with the gaskets. I cleaned these up and reinstalled. I also adjusted the floats to 14 mm because I was there. They were close, but not perfect.
So now I just get to put everything back together and play with it when the weather breaks. I will fine tune, sync the carbs and post some follow-up pictures. [Dolph]
How did you go? [popcorn]
I'm still waiting on the weather...still have to put the carbs back on. What's the best way to attach the throttle cables? I always remember it being a bear in the past (which is why I try to leave the carb on as much as possbile).
I also noticed that one of the vertical cylinder valve cover gaskets were leaking. They are the paper kind, so I will be replacing them with OEM metal.
When I put everything back together I will be replacing the original spark plug wires with NGK Racing wires too. [Dolph]
Getting the cables on is a pita for surem because you need three hands for the second cable. One is easy, but the other requires careful routing not to rub and rotating the throttle pulley. Try and lock it into place with a small Allen key or something lke that. Mechanics gloves help with pinched fingers.
I remove the cables from the throttle housing end now days.
Update
Everything is back together and running. Unfortunately, I experienced the same issue about an hour into a ride yesterday. Everything was great, and then the engine started bogging at cruising RPMs. Every time throttled was applied the engine would just bog down. It got worse and worse until I was forced to pull over. It would idle fine, but any throttle would just bog until it would stall itself. I turned it off, removed the air filter (which I just replaced as I thought the previous one may have been clogged) and it ran just fine and took full throttle without issue. Maybe I unkinked fuel lines when I lifted the tank...I don't know. I only had about a mile to make it home, so I ran it without any air filter for that short time.
Here's what I have done this winter which related to this problem:
- Replaced the internals in the vacuum fuel pump
- Upped mains to 165 Mikuni OEM jets
- Added heatshields to fuel lines in case they were collapsing
- Replaced the fuel filter
- Replaced the air filter (K&N open airbox)
- Replaced spark plugs
I plan on balancing the carbs soon...besides that, what other items should I be looking at?
When it bogs, runs on one cylinder or do both bog? Could a coil be dropping out when hot? Can happen.
How much oil in the air filter?
Maybe you did fix a kinked line.
As an Aussie don't know your weather but any chance the carbs are icing?
How cold is it there?
It feels like both cylinders are bogging. I am not 100%...I will try to determine that the next time it happens. But there are no abnormal vibrations like one cylinder is dropping.
The air filter was brand new, right out of the box. The pleats looked the normal pinkish red - nothing excessive or dripping.
It was around 60 F / 16 C when I was on the ride.
Another thing I saw come up searching the forums were clogged vent lines. Is there any good way to test these to see if the little filters have become clogged? Suck on the end and see if I get a mouthful of gas? ;D
Fuel starvation?
Open the cap and see if it gets better
Also confirm your fuel pump delivers sufficient fuel.
Quote from: ducpainter on March 24, 2016, 06:36:20 PM
Fuel starvation?
Open the cap and see if it gets better
I opened the gas cap when it happened, and I did not have a "whoosh". Also, I can draw through the gas tank vent lines with no problems.
Quote from: howie on March 24, 2016, 08:32:07 PM
Also confirm your fuel pump delivers sufficient fuel.
I will add this to the list and check back.
This is starting to get frustrating. [bang]
I was letting the bike idle while I was cleaning out the garage. About 5 minutes into idling it was warmed up, and I cracked the throttle a couple times and it revved up fine. A few minutes later, I tried to rev it again and it bogged and died.
I drained both bowls, and only got ~ 2 beer bottle capfuls (extremely scientific measurement) out of each bowl. I figured that I found the issue. For shits and giggles, I waited a few minutes and started the bike back up, turned it off and checked the bowls again. This time, fuel kept flowing out and did not stop. I'm guessing that it's a fuel pump issue, because it should be closed with no engine vacuum on it right? I have almost a full tank, but I wouldn't think it would force it's way past the pump membranes just by gravity.
(http://i.imgur.com/fmi00Wrm.jpg)
A full tank can flow thru but once past half a tank or so. You fitted a manual tap and deleted the vacuum tap iirc?
Correct, and I had the petcock open, so that would explain that.
Also, I am going to change the vacuum line from the intake manifold to the pump just to be safe. Do you know the ID off the top of your head?
After some searching, it looks like it is a 5mm vacuum hose.
But the lack of fuel at idle leads to a bad pump since you now have a manual petcock. The fuel pump can pump less fuel when hot. You are also correct that a collapsing vacuum line can be a problem, as can be the fuel hose that runs from the petcock to the pump, particularly if it is the original hose, running close to the engine.
This is what I did with my 750, using heavy walled fuel hose.
(http://i298.photobucket.com/albums/mm276/hlep2890/bike/IMG_0422.jpg) (http://s298.photobucket.com/user/hlep2890/media/bike/IMG_0422.jpg.html)
You can buy a new pump or rebuild kit here.
http://sudco.com/Catalog37Digital/index.html#/222/ (http://sudco.com/Catalog37Digital/index.html#/222/)
Their pump comes with two outlets, but it is a lot cheaper than OEM. Just Y them together.
Thanks howie.
I rebuilt the pump this past fall with a Mikuni MK-DF62 kit (http://www.ebay.com/itm/Mikuni-FUEL-PUMP-Rebuild-Kit-MK-DF62-Hexagon-5-sided-/271723967187). I rebuilt it because I originally diagnosed the pump when this problem started.
Along with replacing the vacuum feed to the pump, I will replace the fuel line from the petcock (my petcock is before the fuel pump) to the bottom feed of the pump. The original fuel line makes some pretty crazy bends to get to the bottom feed, and it also sits in the corner made by the engine case and vertical cylinder - it must get pretty warm there.
I wonder if e fuels eat pump components up your part of the world?
Quote from: koko64 on March 29, 2016, 01:16:46 PM
I wonder if e fuels eat pump components up your part of the world?
Definitely shortens the life, but not that fast. Still could be a pump problem. I don't know what the proper volume at idle would be for that pump installed on a Ducati, but that would be the true test.
I always forget, there is a screen in the fuel inlet to the carbs that can clog. Have you checked that?
Well there's yer problem...
(http://i.imgur.com/1P0y4G1m.jpg)
The vacuum hose split where the clamp was on the intake manifold nipple. The pump couldn't draw enough vacuum to keep up with the fuel demand. Seems to make sense to me.
Confirmation that the vacuum line is indeed 5mm...
(http://i.imgur.com/tSZ0H68m.jpg)
Once I get this replaced hopefully the soap opera is over.
[thumbsup]
At least that's a cheap and easy fix.
So turns out that I still have an issue. I will let the bike sit and idle for 5 to 10 minutes and it will eventually bog down and die.
The vertical cylinder spark plug is looking good, but the horizontal is reading way too lean. I need to check for a vacuum leak at either the carb/manifold boot, the vacuum taps, or the manifold base gasket. If nothing checks out there, I will dig into the carbs again.
I am thinking issues in the carb could be a plugged jet, torn diaphragm, or cracked float.
After that I will go to electrical and look for heat soak issues, but the plug is not soaked with fuel when I pull it - so I am assuming fuel delivery issue and not electrical.
Any other advice?
Don't let it idle so long.
One of the first things I noticed is that the vacuum line to the horizontal cylinder has an issue. I can rattle the canister on the line to the vertical cylinder and hear the ball inside, but did not hear it on the line to the horizontal. Half a can of carb cleaner later and now the ball rattles freely. I would like to replace these lines, as they are pretty brittle. Can I omit these canisters? They seem like a one way deal - draw fresh air into the carbs when needed, and shut off by the ball when not drawing air. I imagine to prevent gas vapors from escaping.
I would reroute up near the battery to get them in to still air, since I no longer have the frame pods that they previously connected to.
(http://i.imgur.com/9XHBHl4.jpg)
There are filters in there. Forgot about them :-[ If they clog or the check ball jams you will have a hard time off idle.
I am wondering if the vacuum filter gave up the ghost. None of this crud was in there when I had them apart last time. It looks like the same grit that I flushed out of the vacuum line. [thumbsdown]
Horizontal cylinder carb:
(http://i.imgur.com/xMMxRez.jpg)
Yep.
Quote from: Dellikose on April 21, 2016, 09:43:39 AM
(http://i.imgur.com/9XHBHl4.jpg)
For those who run into the same issue - I had a look inside the filter that is connected to the vacuum lines. As it turns out, there is not a ball check inside, but 2 or more screens to keep out debris. The rattling is from the screens having some free play within the barrel section. I will try to get a picture later.
As you can imagine, mine were seriously gunked up after 30,000 miles. It even looks like there are remnants of a bee caked on one of the screens - poor guy.
After a good cleaning I am going to reuse them, since I would rather have the protection so nothing gets sucked up into the carb diaphragms.
Edit: Here's a picture of the filter after cleaning.
(http://i.imgur.com/YINmzwf.jpg)
Well, I still have the same issue even after all of the cleaning. The bike idles decent, I still can tell that it is a bit off, but when very slight throttle is applied it will bog and backfire through the carb. When I pull the plugs, the vertical cylinder is fine, but the horizontal is white. It smells a little like gas, but not soaked as if the plug was not firing.
I ran a compression test just to ease my nerves, and came up with 125 psi on both cylinders - so at least the piston isn't cooked. I also checked the pick up resistance and came up with 105 ohms on both cylinders. One last thing I checked was the gasket between the intake manifold and head, no issues there.
I'm still leaning (ugh) towards fuel starvation.
Here is a list of all that I have done to try and fix this issue. I am going to check the valve clearances and then pull the carbs once again for another cleaning, and to make sure that no more grit is inside.
New Parts
165 Mikuni Jets and o-rings
K&N air filter
Rebuilt fuel pump with Mikuni kit
NGK spark plug wires
NGK spark plugs
Fuel filter
Fuel pump vacuum line
Fuel lines with heat shielding
Manual petcock
Checked
Cleaned carb
Set floats to 14mm
Cleaned carb vacuum pod filters
Timing and belt tension
Vacuum leaks
Carbs synchronized
Cleaned all gas tank vents
Pick up resistance
Switched ignition modules
Carb slides open evenly
Have you verified both slides are lifting?
Yes - I forgot to add that to the list. I ran the bike without the air filter on last night and saw both slides lift evenly as I applied throttle. I was also able to see the atomized fuel come from the needle valve. One other thing I did was to spray a little carb cleaner down the 2 small ports (idle passages I assume since they are before the throttle plates) on each carb and the bike would stumble a bit.
I also noticed that it coughed out of the carb on both cylinders with the slightest amount of throttle, but rev fine once I got past the initial tiny application.
What does this cough feel like when riding?
Is it pronounced?
Yes, it is pronounced. It feels like a complete miss.
What is a good testing procedure for the fuel pump? Just disconnect it at the carb and aim it towards a bucket and crank? What sort of flow am I looking for?
I don't think it's a fuel pump problem with regard to the cough. If you can fill the bowls it should respond to throttle. Fuel delivery issues would occur at wide open throttle.
That said a typical Mikuni diaphragm pump puts out ~35 l/hour.
What are your fuel screws set to?
I am currently at 4 turns out from seated.
Quote from: Dellikose on May 04, 2016, 12:00:06 PM
I am currently at 4 turns out from seated.
Open/drilled airbox with cans?
Open air box with stock cans.
Quote from: Dellikose on May 04, 2016, 12:05:35 PM
Open air box with stock cans.
Have you tried screwing them in a half turn or so.
I'd ride it too instead of just trying to work everything out while the thing sits and gets hot from not moving.
That low cough is in the idle mixture and pilot jet zone. It's either a rich stumble type cough or lean hesitation type cough (or out of synch cough). Turn it in as DP suggested to see if the cough is more or less pronounced.
Thanks guys.
I will turn the idle mixture screws in (clockwise) - this should lean the idle mixture, correct?
I have the carbs off the bike now, so I will bench sync them to get a baseline and then sync them again with the bike running after they are reinstalled.
Yes. Try that and see if it improves response. Try half a turn at a time.
It's getting a little better as I get the carb dialed in.
One question I have is that my vacuum taps on the intake manifolds are not the same size. One is 5mm and the other I had to drill and tap to 6mm a long time ago since it got stripped. Would this imbalance my manometer when I try to sync the carbs with the bike running?
As for the backfiring mentioned earlier in this thread, here is a still from a video I took. You can see the orange flame behind the slide on the left (horizontal) carb. From everything I read, this is a lean condition. That's what my spark plug says too.
(http://i.imgur.com/70j9osY.jpg)
I don't think vacuum tap sizes make one iota of difference because the measurement has nothing to do with flow.
The only other comment I'd make is you can't really tune a bike statically. Ride the thing.
Heading out tonight ;D
Well, I didn't even make it out of the driveway. Same symptoms...the horizontal cylinder would drop and any attempt to add throttle would make it fall flat. It only idled for the amount of time it took to put my jacket, helmet, and gloves on.
I drained the gas and noticed that it was orange/yellow...I let it sit overnight, and no rust settled out. It could be that the ethanol absorbed some water and separated out. The gas didn't smell rancid, and wasn't very old.
I drained the tank by disconnecting the line from the fuel pump to the carb. It drained the entire tank...koko mentioned earlier in the thread that it should only drain from a full tank to about ~ 1/2 tank, so I guess the rebuild kit isn't installed correctly.
If the outlet is lower than the tank you are ok. It's just the carb inlet is high.
Thanks. The outlet was indeed lower than the tank when I was draining it.
If that cylinder is getting fuel you could have an ignition issue. Plug black? Or not black but wet? Or dry? You can ground the plug to the motor and see if you lose spark.
The plug smells a little like gas, but it is dry - not black at all.
I've sprayed every passage with cleaner and blew it out with compressed air. Also verified that the diaphragm has no holes, and all of the gaskets are intact.
I grounded the plug to the engine and have great spark.
Must be a fuel blockage or one slide is not rising. The diaphragm can unseat when you put the top on and then not raise the slide. It's a common and annoying problem.
Some soak the rubber in WD40 or spray it with carb cleaner to expand it so the rubber lip fits the recessesed ring of the carbs.
Caution, some carb cleaners may be too strong and dissolve some rubber. The stuff here has been softened to not kill you by the EPA so it only swells the rubber. Doesn't clean as well.
I'll try soaking the diaphragm in WD40 and check for fuel blockages.
The only other thing in the carb that would limit the fuel would be a sticking float, right? I think a cracked float would flood it.
Before you tear into it, pull the airbox lid and filter, and start it.
Visually check that both slides move in the same way, bouncing the same way at idle, and sliding up the same when you rev it up.
Watch your eyebrows, as it was backfiring out the carbs before....
Yep. Sticking float valve starves and sinking float floods.
Visually check it as Speeddog suggested. Can save a lot of work for nothing. Easy with pods. I run pods until I'm satisfied the diaphragms and slides are working correctly before I fit an airbox. I have had to pull the top off a carb 3 or 4 times until the rubber seated correctly. I recently found a local supplier of diaphragms and slides that are about $100 a pair for the complete parts.
I'm starting to lean towards an unseated diaphragm lip. Pita and not uncommon.
I checked the diaphragms, and both move in sync at idle and with throttle.
Do you guys think it is worth it to take off the side cover and check the pick-up clearance?
Pick up clearance doesn't change. If the bike ran well before I don't think that's your issue.
I'd start swapping electrical components between cylinders. Be careful if you swap the ignitors. They're fragile and expensive.
You could also check the pickups for resistance. howie knows the spec, or you could dig it up here on the forum. Another thing to check is the insulation on the pickup wires where they pass through the case.
I've already swapped the igniters and there was no change.
Here is what I found in the workshop manual as far as pickups...
(http://i.imgur.com/NYQrkal.jpg)
(http://i.imgur.com/eeJUGvI.jpg)
I'd test the pickups and coils cold, and hot.
Ignition components can function fine then fail once hot especially coils.
I had one that opened intermittently. After replacing it (diagnosed bad on the road) I brought it to a boil slowly. Failed at 180o.
I'm trying to perform a leak down test, but the engine keeps turning. Is there an easy way to lock it into place...2x4 through the wheel and swingarm? I'm trying to apply 100 psi to the cylinder.
After this test checks out, it's on to the ignition system.
If the engine turns over when air is applied the piston is not exactly on top dead center.
Was this issue resolved?
Not yet, unfortunately. I am still running lean on the horizontal cylinder.
I did not get much done over the winter, but now that riding season is back I plan on getting some updates with my findings.
Well, this problem is still going on. While I have been able to get both cylinders closer to the fuel mix they need to be, but I am still having a problem with the engine cutting out after riding for 30 minutes or so.
I went for a ride today and had the issue. I rode for about 30 minutes with no issues at all, and then the engine began to bog and eventually died. I would let it sit for 10 minutes, start it up and ride for another couple of miles and then the same thing would happen again...rinse and repeat until I got home.
The only thing that I can think of that I did not physically check myself was the pickup clearance...anyone have a good walk-through?
I'm always open to other suggestions [bang]
edit: I'll probably just go through the entire ignition system as Koko mentioned.
You'll hate me if it's a carb problem ;D
On these old bikes I just upgrade/refresh the ignition components to get them running smoothly and upgrade everyday performance.
I have seen similar symptoms from ignition pick ups, ignition relays and coils going bad. You may have had more than one issue on an old bike, both fuel and ignition, so that it throws a curve ball re diagnostics. On old vehicles there may be a number of components that have degraded over time to all contribute to rough or unreliable performance.
So, with that in mind I find myself fitting Exactfit coils, new pick ups (if I have any doubt about them), ignition leads, maybe an Ignitech I tune for smoothness (if any doubt about the boxes), manual tap (if it has a vacuum tap), new needle jets, carb service, jet changes if required and tune. You have completed much of this.
Quotehaving a problem with the engine cutting out after riding for 30 minutes or so.
When that happend to me, it was a malfunctioning diaphragm in the fuel pump.
Maybe try a Mikuni Rectangular pump. Economical option.
I rebuilt the fuel pump with a Mikuni kit. I tested the pump by pulling a vacuum through the hose and I got some good squirts coming from the outlet hose, so I feel good about it. I will keep it on the list possibilities though.
I'll get out the multimeter and start getting some readings and digging into the ignition. Electronics are not my strength, so time to learn.
When the bike quits on you (you need to be fast) get out your ohmmeter. The two wire plugs at the ignition modules are from the pick ups. Each coil should read 95-100 ohms. The other option, which eliminates operating a faulty bike, is remove the pick ups and boil them with an ohmmeter attached. If they pass first determine which cylinder is misfiring (if that is the problem, I didn't re read the whole thread) switch modules and see if the misfire moves to the other cylinder. No change do the same with the coils.
Just so I have the nomenclature correct...
Ignition modules are the 2 black boxes...Kokusan. What is their function?
Pick ups are on mounted behind the engine cover, and are mounted to “pick up†the spark timing from the flywheel.
Coils are the 2 black cylinders next to the rear of the air box. They step up the current to be supplied to the spark plugs.
When the bike begins to die, it really feels like it is both cylinders at once. I noticed popping from the exhaust when it was happening - like it was lean. That would lead me to think fuel starvation, but it is dead simple fuel system that I don't see where else to look. No vacuum petcock, new fuel lines with no kinks, and rebuilt fuel pump with new lines to it.
After I check the ignition I will go back to the carb, but I've been in there so many times it makes me wonder what else is left to check.
Re read the thread. Pick up clearance is .6-.8mm. You need a non magnetic gauge. Wow, this has been going on for two years. My only two suggestions are; a) check all grounds b) start from scratch, item by item. All I can think of is one thing got fixed, one thing got broken. Part of from scratch is fresh fuel.
Yep, I had to as well.
Might as well start fresh.
Besides trying another fuel pump (little "22" model is 20 odd bucks iirc), a thorough check of the ignition by a pro is in order. If you can't access a pro then slow and carefully considered diagnosis is the key. It's called electrickery for a reason so follow Howie's guidance very carefully.
You guys are right. I'm going to start over again since so many parts have been changed. I'll let you know what I find.
Ignition modules gives the ignition advance pulse, when to fire plugs.