When I was first done with the mods I was stoked because I could do gas wheelies...then I started becoming very dissapointed in the power, espec freeway passing power. So I recently had it dynoed, thinking something may be up. Well the shop said the dyno found nothing wrong and the bike runs great, but that's my RWHP. I thought 900ss engines were supposed to be 80 fully stock, and I have a race exhaust, FCR's, and pods? is something wrong here? I'm pretty disappointed. Any thoughts on this? That's a lot of cash I put out to barely get more than my 750 was giving me...
http://bikeboy.org/900SSwithkeihinfcr39and41mmcarbs.html (http://bikeboy.org/900SSwithkeihinfcr39and41mmcarbs.html)
Dynos can vary... but there you are.
just to clarify what you'de done because I am too lazy to go dig and look...you just bolted in a 900 motor with FCR41's on right? You didn't do any hot coils, not head work, and no kind of bore kit or anything right?
FCRs on their own don't usually add to dyno numbers, but the performance increase shows up on the butt dyno. Some tuning and better coils, like Chris Kelley's Xact Fit coils might add to the numbers.
I didn't do any engine work, no, aside from new rings. I bolted on the 900 motor and added FCR's. I do have CK's Dynacoils.
Thoughts?
Quote from: Dirty Duc on September 27, 2013, 11:27:08 AM
http://bikeboy.org/900SSwithkeihinfcr39and41mmcarbs.html (http://bikeboy.org/900SSwithkeihinfcr39and41mmcarbs.html)
Dynos can vary... but there you are.
Ok then...I guess that's about right. :-\. I really can't complain too much I guess...The "streetability" of this bike is great, it's super fun...I had just hoped for more top end power for my highway riding. And TBH I already thought my 750 was a fantastic street bike. Oh well.
Have you thought of re-gearing? What are your sprockets at? If you're running like a 43T rear sprocket it might 'behoove' you to come down to a 40 or 41 to get a little bit more top end.
Quote from: ChrisK on September 27, 2013, 12:23:52 PM
Have you thought of re-gearing? What are your sprockets at? If you're running like a 43T rear sprocket it might 'behoove' you to come down to a 40 or 41 to get a little bit more top end.
I ended up going with 15/41.
Quote from: ChrisK on September 27, 2013, 12:23:52 PM
Have you thought of re-gearing? What are your sprockets at? If you're running like a 43T rear sprocket it might 'behoove' you to come down to a 40 or 41 to get a little bit more top end.
I'll submit that with 67hp to the rear wheels, you'll benefit to going shorter on the gearing rather than taller as ChrisK suggests. Top speed on a 2v Monster is usually drag-limited, you can pick up a few mph by gearing for acceleration. It will rev higher at a given road speed, but it might make it feel a little more peppy.
I'm running 15/45 on the 800...
Yeah, well you can always come down to 39... or just buy the S4RS you're after [beer]
Play around with gearingcommander.com if you're interested in that.
Quote from: Dirty Duc on September 27, 2013, 12:38:08 PM
I'll submit that with 67hp to the rear wheels, you'll benefit to going shorter on the gearing rather than taller as ChrisK suggests. Top speed on a 2v Monster is usually drag-limited, you can pick up a few mph by gearing for acceleration. It will rev higher at a given road speed, but it might make it feel a little more peppy.
I'm running 15/45 on the 800...
I suggested to come down on teeth just because I thought he wanted more top end, maybe I misunderstood his desired results.
Quote from: ChrisK on September 27, 2013, 12:39:49 PM
I suggested to come down on teeth just because I thought he wanted more top end, maybe I misunderstood his desired results.
I am interpreting Buck's concern as an acceleration problem - a smaller rear sprocket will make the bike accelerate slower and thus feel under-powered. It will make the nominal (calculated) top speed higher, but neglects the (lack of) aerodynamics of a Monster.
Larger rear sprocket (or smaller front sprocket) has the opposite effect: accelerate more quickly, but with a lower theoretical maximum speed. On a 2v Monster (relatively under-powered for a motorcycle) the key is to balance the limitations of aerodynamics with the limitations of the gearing (keeping in mind rider preferences and "normal" use for the particular bike).
I get what both of you are saying. But I believe my issue is just power...I love the way the bike pulls around town and in the twisties. I just wish I had more "oomph" when I'm accelerating from around 70-80 mph or so. I want to be able to blow by asshole cagers on the freeway a little easier.
Quote from: Buck Naked on September 27, 2013, 01:01:25 PM
I get what both of you are saying. But I believe my issue is just power...I love the way the bike pulls around town and in the twisties. I just wish I had more "oomph" when I'm accelerating from around 70-80 mph or so. I want to be able to blow by asshole cagers on the freeway a little easier.
Drop 2 gears and give them bird as you go by. That'll make you look even faster!
Quote from: Buck Naked on September 27, 2013, 01:01:25 PM
I get what both of you are saying. But I believe my issue is just power...I love the way the bike pulls around town and in the twisties. I just wish I had more "oomph" when I'm accelerating from around 70-80 mph or so. I want to be able to blow by asshole cagers on the freeway a little easier.
And that's why I run the gearing I do.
Quote from: Dirty Duc on September 27, 2013, 01:11:46 PM
And that's why I run the gearing I do.
How does it behave around town with that setup?
Quote from: Buck Naked on September 27, 2013, 01:18:45 PM
How does it behave around town with that setup?
Much nicer. I think I have slightly different gearing than your engine, but 1st feels like 1st instead of 2nd. There is a speed limit or two that is right in between gears by my riding style.
The only thing that might be considered a drawback is that 80 on the clocks is around 5500rpm. If that annoys you, you won't like it.
you need to find out what other bikes make on that dyno, or if you know someone with a similar bike have them run it and see.
what was the mixture like? maybe you need to put the airbox back on.
My M750 squeezed ~58 RWHP about 6 months ago.
FP Jet Kit, Termi cans.
Oooh! I've got an S4RS for sale! Guaranteed more than 67.2 rwhp!
Shameless plug: http://www.ducatimonsterforum.org/index.php?topic=65294.0 (http://www.ducatimonsterforum.org/index.php?topic=65294.0)
Quote from: $Lindz$ on September 27, 2013, 08:02:16 PM
Shameless plug: http://www.ducatimonsterforum.org/index.php?topic=65294.0 (http://www.ducatimonsterforum.org/index.php?topic=65294.0)
[thumbsup]
Quote from: Dirty Duc on September 27, 2013, 12:38:08 PM
I'm running 15/45 on the 800...
I've heard/read (on here and elsewhere) that having multiples for gearing can lead to abnormally fast chain and sprocket wear.
Any issues that you've noticed?
Also, out of curiosity, how many links in your chain?
Quote from: Buckethead on September 28, 2013, 08:13:57 AM
I've heard/read (on here and elsewhere) that having multiples for gearing can lead to abnormally fast chain and sprocket wear.
Any issues that you've noticed?
Also, out of curiosity, how many links in your chain?
I went out to count links, and I lied. 15/44 with 104 links. This set has been on for a year and a half or so, and only about 7k miles because of some other issues.
I appear to go through chains like nobody's business anyway. The 15/44 set-up is also not ideal because of the chain length (I think). I can tell because the clean part where the chain rubs looks non-random.
You may have the motor producing 80hp at the 'crank', however there are frictional losses along the way transmitting power from the drive shaft to the rear wheel. You typically lose 15-20% of power. 67 RWHP sounds about right.
Buck-my '98 M900 is set up the same. FCR 41's w/ ExactFit coils and K&N pods, 15/41 gearing. I've got Chris Kelley's stock jetting on the 41's. My bike pulls great in the low and mid range -light front wheel-but seems a bit flat at higher rpm's. Even flatter than stock carbs w the same 15/41 gearing. It also hates cruising at 30-40 mph, seeming to hunt and wanna accelerate, not cruise at those speeds. A small but noticable flat spot at hwy speeds of 55-65ish until higher rpms and speeds. I'm thinking of trying larger main jets in lieu of a $300 dyno tune. Or a 42T rear sprocket. Let me know what else you try. Anyone have any more suggestions?
OTH, I did record 61mpg and 58 on the next tank while busting across TN at about 80mph consistently. I usually get 33-38 mpg's w/ in town use only.
Quote from: silas on October 18, 2013, 07:43:11 AM
Buck-my '98 M900 is set up the same. FCR 41's w/ ExactFit coils and K&N pods, 15/41 gearing. I've got Chris Kelley's stock jetting on the 41's. My bike pulls great in the low and mid range -light front wheel-but seems a bit flat at higher rpm's. Even flatter than stock carbs w the same 15/41 gearing. It also hates cruising at 30-40 mph, seeming to hunt and wanna accelerate, not cruise at those speeds. A small but noticable flat spot at hwy speeds of 55-65ish until higher rpms and speeds. I'm thinking of trying larger main jets in lieu of a $300 dyno tune. Or a 42T rear sprocket. Let me know what else you try. Anyone have any more suggestions?
OTH, I did record 61mpg and 58 on the next tank while busting across TN at about 80mph consistently. I usually get 33-38 mpg's w/ in town use only.
That's funny, we have identical situations. In the 30-40 mph range, does it feel almost like a rapid series of tiny misfires? kind of like stumbly/hiccupy until you wack the throttle some more?
And that flat spot you're talking about at HWY is by far the most disappointing thing. My 750 motor with a jet kit and chopped airbox pulled better at those speeds. THAT is the real WTF for me.
I'm wondering if its our pods actually. The power curve on the dyno was beautiful, progressive and smooth is the good news and the techs couldn't see anything they would suggest changing. I would go back to an open airbox before I tried anything else.
Yes and yes! Hates slow traffic -hunts unless accellerating-and poor accel @ hwy speeds. I need to find a solution as-is. I hacked my air box off, leaving the battery box & coils hanger intact. I love the intake sucking and honking too much with pods to go back to an airbox...plus the open frame look. I think you're right-the airbox works better than pods-possibly @ hwy speeds mostly-but I'd like to see if my setup can be improved. Not going back to an airbox.
Yes, My old injected '99 750SS also pulled harder on the hwy than my current setup
Those carbs need to be tuned correctly to the intake and exhaust mods of your motors. What mods exactly and what jetting you guys running?
98M900, ExactFit coils, Arrow slip ons, FCR41's w/ stock settings, pod air filters..
Engine totally stock. 30K miles. 5k miles on this setup w/carbs & coils. I have not messed w the FCR's or checked the below listed stock settings internally. I Really want to keep the pods.
My carb settings(stock from Chris Kelley):
Fuel mix screw: 3/4 turn
Slo air 1 - 1 1/2 turns
Float ht 9 mm
Main jet 155
Main air jet 200
Slow jet 60
Needle EMT
Needle clip 3rd pos.
Thx ahead for any suggestions for us.
Do the heads of your motor have a "W" scribed onto them?
Exactly what silas said except I have a Roadracing full exhaust. My engine has V heads, I made sure of that before I bought it (thanks Brad Black)
No, I swapped to the V2 heads from A 900SS a while back. Made a small difference at higher rpms (head swap prior to carb & coils upgrades).
Apparently some '98's came w the V heads but I had to switch to them .
Ok, thats good. Brad did the same for me too. His generous sharing of knowledge has helped many.
Im guessing your pods are the K&N RU 1750s?
Did the dyno guys test for air fuel ratios at various throttle openings or just a power run?
Straight up I would consider going up to 160 main jets and see if that improves things up top when you want to overtake quickly. Greenmonster runs 162.5s with pods (Scandinavia), I ran 160s {Australia). I'd like to see what the locals are running with pods on local fuel, but you get the trend.
Changing the main jets is easy on these racing carbs, you just need to be careful with blocking the fuel and catching the fuel spill. You access the main jet via the big alloy nut on the bottom of the float bowl. Hex head main jets require a tiny wrench 6mm iirc. Be gentle, imagine stripping that thread... Check Chris Kelleys site out. A spray can cup works well to catch the fuel. Do the work with the motor cold...
The safest place to test main jets is the dyno, but I think you should feel the difference one way or the other on a highway overtake.
Stay with the #3 needle position for the moment.
Thats step one.
Step two requires you first read Patrick Burns "Keihin FCR Tuning Procedures".
Tuning the slow fuel circuit requires patience and involves the slow fuel jets, slow air screws and idle mixture screws. They all interact and overlap at some point. A perfectionist could spend a lifetime in this area.
If the bike idles well, has good plug colors and is smooth at low speeds and small throttle openings then your settings are close.
Lumpy running, fuely idle, black plugs and poor cruising fuel economy are symptoms to alert you to fix this area. I doubt the slow fuel jets are too small.
Let us know more about the low speed throttle characteristics and we can give feedback. It will be interesting since your exhaust systems are at opposite ends of the spectrum.
Cheers and be careful.
(http://i57.photobucket.com/albums/g234/247prophet/dynorun_zpsf9d7c7a0.png~original)
when you right click and view this, the resolution is actually quite good considering I only photo'd it. Helpful at all?
It is definitely too lean from 6000 to 7500rpm. Put in 160 main jets as the area of peak hp on these motors is too lean. You can see it's too lean where it counts, but that's actually a relatively flat a/f curve compared to some I've seen, but the hp bump from 6500 to 7500 is missing. The power peak looks chopped off the curve. That lean area can be felt as a lack of acceleration.
Kiki-my bike has not been dumped. It does idle well and the plugs look good. I will try larger main jets. Relay appreciate your info & ideas! I'll post back after trying it.
Koko-sorry, darn device
Quote from: silas on October 19, 2013, 05:16:24 PM
Kiki-my bike has not been dumped. It does idle well and the plugs look good. I will try larger main jets. Relay appreciate your info & ideas! I'll post back after trying it.
Maybe your exhaust set up may make tuning less pernickerty down low.
Chris at CCW has to provide a base setting for all comers, then us guys go and do mods! ;D
Yes, and mine is very close already. I Love the sounds from the pods (and the open look)
Quote from: Buck Naked on October 19, 2013, 10:23:37 AM
when you right click and view this, the resolution is actually quite good considering I only photo'd it. Helpful at all?
did someone tell you that mixture was ok? it's way too lean. if it has 155 now i'd be going 165 or more. one of the reasons I am liking 39 over 41 is that the wot curve seems to be much flatter with 39. you also run a smaller main jet, but that's due to the venturi airspeed differences. 39 on my 750 show the same lumpy air/fuel as the 41 on a 900.
I'd go 165s on an open airbox, but I think the pods (RU1750s) run a little richer in the midrange and top end. I thought they'd be leaner, but the ega surprised me. An extra dollop of fuel wouldnt hurt and its foreign fuel. Greenmonster is running 162.5s.
Be interested to see if the dyno guy said it was ok as it's clearly not.
Something I forgot, too rich an afr seemed to hurt hp more with pods than an open airbox. Shorter stacks in an open a/b allowed even richer again, helping midrange WOT hp/torque without hurting peak hp much.
Quote from: koko64 on October 20, 2013, 06:26:21 AM
Be interested to see if the dyno guy said it was ok as it's clearly not.
Quote from: brad black on October 20, 2013, 12:07:01 AM
did someone tell you that mixture was ok? it's way too lean.
Yes. Maybe I'll start with 162.5 and go from there? Or if they're cheap enough I'll buy several.
Cool, why not. [thumbsup]
Quote from: koko64 on October 20, 2013, 07:18:50 AM
Cool, why not. [thumbsup]
Should I adjust the fuel mixture screw maybe a 1/4 turn in the meantime? It actually starts and idles quite well for the most part though...would rather not get too much in to fiddling with those settings :-\ I have somewhat of a "hanging" of the RPM's and a slow drift down when I release the throttle, and it's a bit "breathy" if that makes sense.
Yeah, try it. With a hanging idle you usually need to richen the idle a little, say out a 1/4 turn on the screws. Breathy?
Write down every move by the way.
Koko, Brad, Buck ...thx for all the help. I'm not good at carbs but prefer to fiddle myself at the moment. I installed the carbs & coils...easy. My bike has not been dynoed but is the same setup as Buck's except with Arrow slip ons. I will try 165 mains and report back.
In Atlanta Ga it's usually on 10% ethanol gas. We have to go 45 mins N to the base of the Blue Ridge mountains to get 100% real gas. "Foreign fuel"-ethanol !
Buck, 'slow drift down' from what rpm? I get the hanging idle sometimes also but only when cold & avoid it by backing the idle screw off a tad more after it warms up more. Have you checked your throttle cables for kinks?
Here's an email I got from Chris Kelley in RE: to my situation;
"The main jets have nothing to do with closed throttle to 1/3 throttle, which is where all of your negative symptoms are coming from. Then, you're using pods, which I normally recommend against. And finally, I don't know what's up with the race exhaust. The OE exhaust header actually flows really well, which (as usual) I had to learn the hard way to believe it.
The dyno graph doesn't tell me a whole lot other than your HP peak seems located about right (torque peak is probably near 6000) and I'd like to see that closer to 80hp than 70 :P. I think with the race exhaust and the pods, you're going to need to pay a shop to really dial in the FCRs. That's where they iteratively make a jetting change, ride the bike, come in, make a change, repeat. Additionally with the rideability improvement you'll be asking for, get them to "dyno tune" the main jet at WOT (like normal dyno runs) to try and improve the max hp number.
Remember that with normal riding around town, the speed or gear has nothing to do with the jets or circuits. These aren't like CV carbs, where the needle clip can affect idle and/or the mains and vice-versa. So for your 30-40 stumble could be needle clip position. The > 80 flat spot is probably the 67 hp. :P Slow return to idle could be too rich or too lean and can be affected by the fuel screws, slow jets, slow air screws, and float height."
:-\
That afr trace shows lean mixture at WOT at peak hp. That means too small a main jet with pods. Go the the 162s. Ethanol leans things out a bit, so if your fuel has ethanol definately go 165s. A fat main jet may cost a peak pony, but too lean could cost that and your motor.
Listen to Brad, hes done more dyno tuning than most. Your main jets are too small for pods, period.
Main jet isnt the cause of whats happening down at small throttle openings, you have to dial in the slow circuit to tune that.
If you are not confident about what to do, book your bike in with speeddog, duck-stew or someone like that. PM those guys for someone near you if they are too far. If the guy that dynoed your bike said the afr was good for a WOT power run, then do not let him tune your bike, honest.
I recall someone saying that the needles were too rich, but what they were saying or what i am remembering didn't make sense as they were talking about going to an emr, but that that's richer due to a smaller root diameter. a larger root diameter needle may help with the low speed richness in conjunction with the smaller pilots, etc. I hadn't thought of that before, but with the dellortos we would often drop from a 265 needle jet to a 264, which on a bevel 900 with phm40 really makes a difference to cruise mixture. much nicer for a 0.01mm change in jet diameter.
might need to try some emu or emv some time.
http://www.jetsrus.com/photos/photo_keihin_needle_N427_OC_aftermarket_chart.JPG (http://www.jetsrus.com/photos/photo_keihin_needle_N427_OC_aftermarket_chart.JPG)
[popcorn] Subscribed. I'm keen to learn w.t.f. is up with the pod folks. ;D
Quote from: Buckethead on September 28, 2013, 08:13:57 AM
I've heard/read (on here and elsewhere) that having multiples for gearing can lead to abnormally fast chain and sprocket wear.
No. Please stop the rumors.
Quote from: chris on October 29, 2013, 03:09:19 PM
[popcorn] Subscribed. I'm keen to learn w.t.f. is up with the pod folks. ;D
Clearly the RU 1750s flow enough to let MBP motors make 100+hp.
When I dynoed pods Vs open airbox, I found that the pods needed a little less fuel at WOT and at 1/2 and 3/4 throttle pos-ns. It was a main jet size or two and maybe a notch to 1/2 a notch on the needle. At 1/8 - 1/4 throttle it was a tweak here and there on the slow air jet screw. I found the pods made a little less peak torque. They seemed a little more sensitive to being too rich at peak power on the afr curve. There was only a couple of ponies in it on the dyno. Shit they were loud (I must be getting old). Pods felt more responsive just off idle, kind of more revvy.
The bike has JEs and porting, so maybe less difference on a stocker (I really dunno).
Been hanging out with Cagiva Elefant folk (they're a hardy lot). I would run pods on a late carbed model Elefant in an attempt to get more airflow towards the rear of the motor. Those things shroud the rear cylinder with the tank/bodywork.
Quote from: koko64 on October 29, 2013, 04:52:45 PM
Clearly the RU 1750s flow enough to make let MBP motors make 100+hp.
Agreed, I had them on Pongo when he was at 104hp. A bigger surprise was the OEM header was up for that, too! ;D
@ Silas: did you ever try the 165 mains? I'm retrieving my bike soon and will be fiddling with my own carbs next week when I have access to a warm garage.
Buck, not yet. 2 lil girls & 3 houses limit my time & $ more than desired. Im on it when time allows. Def soon though. I'll post back here when I get'em.
I just found time to lower the clocks & headlight below triple tho.
I fitted the 165 main jets this wknd. Removed the std 155's.
Big thanks to brad and koko for their help!
As a reminder, my '98 M900 has fcr 41's, arrow slip ons, Ca-cycleworks coils, and k&n pods (sawed airbox off). Otherwise stock. 31k miles. Atlanta is about 1000' above sea level and my only test ride was @ 50 degrees or so. 10% ethanol gas.
The bike def. pulls a little harder above 70 mph and in the higher rpms. No adverse effects. It's quicker to pass on the hwy now and has a fatter feeling top end in all gears. Seems to 'honk' louder/ harder when wide open, just a little. Whoohoo. The faster I go the more I notice the jetting change. This jetting feels perfect to me now, I'm no expert.
I'll post back in a few weeks of how my mpg's got affected. Typically I see 35-38 mpg's in town and mid to upper 40's on the hwy, but I have gotten 58 & 61 mpg's on a tank before while @ constant hwy speeds.