Tomcat Posted September 22, 2008 Share Posted September 22, 2008 I've had this bike since April and have put about 3000 miles on it. I've done all the routine maintenance like new plugs, oil change, throttle body synch, etc., in an attempt to cure 2 issues. At 3000 RPM, it has a stumble that I can't seem to get rid of. Like I said, I've synched the injectors several times using the different methods talked about on this forum. I settled on the MICA method and now it runs good except for this stumble. Its only at 3000 and particularly if I am cruising steady or decelerating. The other issue is pinging if I accelerate without downshifting while cruising at 60 MPH or so in 5th or 6th gear. I would expect it to ping if I got into it at 40 in a higher gear but it seems to be hyper sensitive to pinging. Forgive me if this is a dumb question but, how do you time this engine? I've read everything I can find on the subject and all I've seen talks about timing when the engine is being reassembled. Is timing a function of the ECM that is not adjustable by mechanical means? Thanks for any help. Tomcat Link to comment Share on other sites More sharing options...
Admin Jaap Posted September 22, 2008 Share Posted September 22, 2008 Hi Tomcat, if you do a search for stumbling or sputtering you'll find lot's of possible answers. As always my guess is cracked rubber intake hoses. Same thing for pinging. Loads of threads. Link to comment Share on other sites More sharing options...
BRENTTODD Posted September 22, 2008 Share Posted September 22, 2008 Mine does the exact same things, I would like to know how to get rid of them myself. Like you I have done all the mantiance as outlined still no difference. Do you have a power commander or any mods. I have power comander and mistral cans. Steve (fuelcooler)doesnt have either and his bike has never done it, that i can recall. I think in my case it might be in the mapping. I hope one of us can figure this out. Good luck Brent , Link to comment Share on other sites More sharing options...
Tomcat Posted September 22, 2008 Author Share Posted September 22, 2008 I do have Mistral mufflers but no Power Commander. I'm not very familiar with the function of one. Could installing one allow you to "tune out" the stumble that may have been induced by the aftermarket exhaust? Thanks again, Tomcat Link to comment Share on other sites More sharing options...
fotoguzzi Posted September 23, 2008 Share Posted September 23, 2008 my stock Lemans does exactly the same thing only at 4200rpm... when cruising steady it has a cough/stumble always right there at 4200.. I have changed the TPS and synched etc but it's still there. I hope to get the VDST software sometime in hopes that will help me solve it. do you have stock crossover? someone told me the aftermarket crossover brings the stumble down to 3k rpm, don't know if thats a fact or not. Link to comment Share on other sites More sharing options...
Tomcat Posted September 23, 2008 Author Share Posted September 23, 2008 The crossover is aftermarket. Anyone develop this problem after changing to an aftermarket exhaust? No comments yet on the timing question. Was it too ridiculous? Tomcat Link to comment Share on other sites More sharing options...
raz Posted September 23, 2008 Share Posted September 23, 2008 I'm not sure if timing should be read as the valve train or the ignition, so here's my take on both. The ECU handles the ignition advance timing and there is nothing to adjust apart from the map on the chip and the 150 mV base TPS. As for valve timing, some of us have had what appeared to be chain whip scatter due to the weak OEM chain tensioner (possibly combined with worn chain). I could see it with a timing lamp to the flywheel at idle. The reference marks jumped around wildly. I replaced my tensioner with a Valtech type, and the same test showed a great difference to the better. But I can't say I noticed much improvement other than when strobing. For my bike, with worn valve guides and whatnot, I swear the Raceco valve lash spec works like a charm for eliminating that 3000 rpm stumble. It's really like night and day. Everything else gets better too, rock steady idle at any rpm I like and so on. I'm not sure if this is a general effect of giving it a little wider clearance or if my bike needs it mostly because of its' age or so. Another thing that initially got me on the right track towards eliminating the stumbles, was to enrichen the mixture a bit using the idle CO pot that the older bikes feature. But that alone doesn't help if I my valves are a little tight Link to comment Share on other sites More sharing options...
BRENTTODD Posted September 24, 2008 Share Posted September 24, 2008 No i dont have a aftermarket crossover. Raz how many miles were on the bike when u changed the tensioner? Link to comment Share on other sites More sharing options...
BrianG Posted September 24, 2008 Share Posted September 24, 2008 I also experienced that irritating stumble in the 3-4000 rpm range. It turned out that my valve lash was tight. I set them at the .006-.008 specs and the stumble disappeared. As for the pinging, have you been using premium fuel? It's worth a try. Link to comment Share on other sites More sharing options...
Dan M Posted September 24, 2008 Share Posted September 24, 2008 My bike developed this same issue. (stumble but no ping) I already had aftermarket crossover / mufflers / PC3 / pistons / drilled air box lid. The bike ran perfectly with all these mods. The 3000rpm misfire started on one very hot day. Additionally, it will miss at idle occasionally. Since then it has occurred more often. It had all the earmarks of a lean misfire. I looked closely for loose intake boots or cracks. Re balanced the TB's; Re-rebalanced the TBs and set the TPS. No change. Someone here indicated that they enriched that range on the PC3 with good results. I at first rejected the idea since the bike ran so well before and nothing else was changed. Later I did add fuel across the 2500 - 4500 range. Minimal improvement. There has not been that many miles since the last valve lash check but now I'm thinking that my guides are worn and my valves are not holding their spec. That is the next place I'm looking. Link to comment Share on other sites More sharing options...
raz Posted September 24, 2008 Share Posted September 24, 2008 No i dont have a aftermarket crossover. Raz how many miles were on the bike when u changed the tensioner? I replaced it at 46,000 km (roughly 30,000 miles) because I had a wierd ringing noise from the engine and suspected the chain hit something. The tensioner was incredibly weak and the aftermarket one was cheap so I tried it even though I saw no traces of chain hitting covers. The noise did disappear at the time but recently it came back... and I realized it was just an exhaust clamp touching the sump it was really hard to locate where the sound came from, I was sure it was from the timing chest... Link to comment Share on other sites More sharing options...
mdude Posted September 25, 2008 Share Posted September 25, 2008 Switched to stock from Titan ECU last month and voila: the 3000 rpm sputter is back. Its the mapping. Must be. Its more driveable though, the Titan is very brutal... Not sure bout the pinging though, what does pinging sound like? Something like a "ping"? Link to comment Share on other sites More sharing options...
Slavomir Musilek (R.I.P.) Posted September 25, 2008 Share Posted September 25, 2008 mine did the same... around 3000rpm sputtering back-forward-back-forward... It did not before my crash (original exhausts) and engine is 100% healthy. It did only when I installed Leo Vinces and KN filter into original airbox. I also pinged around 5000rpm but only on "full gas" hm... what could it be... Air intake rubbers are new.... what about the sparkplugs? Ehhh... AWFULLY white ... What could that mean? ehhh I Installed PCIII and downloaded fuel map I though that should be suitable from download link in this forum. Result? Clear and balanced idle no sputtering pinging has reduced to minimum (there is some but I guess propper mapping will solve it) sparks finally has the right color... Link to comment Share on other sites More sharing options...
mark.gilmore Posted September 25, 2008 Share Posted September 25, 2008 I got rid of pinging as soon as I put Cliff's unit on 2 years ago. Link to comment Share on other sites More sharing options...
Dan M Posted September 26, 2008 Share Posted September 26, 2008 My valves were all quite tight (near US spec). I set them at 6 & 8 thou. Problem 75% gone. Link to comment Share on other sites More sharing options...
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