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Help/Input Needed - 2002 Speed Triple 955i Stumle/Hesitation Below 3k RPM...

4K views 18 replies 6 participants last post by  inderocker 
#1 ·
Alright.. I've done some searching on this forum and on Triumph Rat for a resolution to my issue... and while I've got some helpful tips, nothing has fixed the issue yet. I've got a 2002 Triumph Speed Triple 955i that is completely stock with the exception of a K&N air filter that I picked up for free, but it came with issues. The issue is, when applying anything more than 1/4-1/3 throttle below 3k rpm's I get a hard stumble/ hesitation until it gets above 3k rpm's... this can be from a take off or while cruising down the road. It will also die if you do one or two low rpm rev's in neutral or with the clutch in. Engine temp is not a factor, so I've ruled out tight valves. I've replaced the coils and fuel pump with known good, used units, installed new spark plugs and a new air filter, done the 12 minute tune, reset the TPS through TuneECU and verified the fuel tank was venting properly. I have a completely disassembled 2003 Speed Triple that I am parting out, which I've been stealing parts from, but I'm not sure where to go from here.... any suggestions would be greatly appreciated.
Thanks,
Daniel
 
#8 ·
fuel restriction? The guy I got the triple from found rust in the tank of the virago I traded for him. I had been thinking it was a carb/float issue, because it would hesitate before hitting a certain throttle position, similar to you. So in a sense it would be fuel either way.

But then again, considering these bikes are basically cars with two wheels, I'd figure it could be the TPS.
 
#10 · (Edited)
Swapped out the IACV hoses, no change. I then checked compression and got some unusually high numbers on 2 of the cylinders.. left to right 160/200/195. I'm also getting a lot of backfire through the throttle bodies whether under a load when riding or when revving it... but always under 3K RPM. It seems more like a lean condition or timing issue. is the ignition timing adjustable on these at all?
 
#13 ·
New data! :D

The baratron is built into the ECM and should accommodate the pressure change - I've had my Daytona up to 10,000 ft and still runs well

There should be a hose from the ECM baratron to the airbox - make sure that hose is not kinked or folded. Doesn't make whole lot of difference if cracked as is really just sensing atmospheric pressure and airbox pressure not significantly different.

So you are obviously 'lean' at the bottom end - which means not enough gas for the volume of air. K&N would actually make situation slightly worse.

Try loading one of the TORS tunes with TuneECU, which will enrich things a bit for you.
 
#14 ·
Fixed! It was the ECM. Out of the hundreds of bikes I've owned, both personal and for resale, I've never seen a faulty ECM. On that note the majority of those do not have tunable ECM's... I suppose someone could of half fried this at some point when tuning it.
 
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