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Discussion Starter · #1 ·
Hoping for some ideas on where to look. A few miles after leaving the house the other day my bike stumbled and sputtered a bit. Bike was cold and just starting to warm up. I didn't think much of it until the next day when stopped at a stop sign again a few miles after leaving my house on a cold bike. This time the idle went up to 1200 RPM and when I went to rev it the bike again gave me a sputter for a few seconds. Each time it recovered within a few seconds. I ride this bike alot and have fresh gas in it. I changed the plugs and cleaned the air filter. Didn't help. It is doing this everytime I ride now. I am hoping someone might have an idea of what it could be. The only mods to my bike are Ness Big Sucker, Stage 1 flash and duals. I have not done any work lately so it's not due to any changes I have made. The bike runs great after this little warm up sputter. The only thing that i can think it might be is a sensor of some sort.
 

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Is your bike fuel injected? If it is, one of the things you might look at is the warmup enrichment table. Your bike might be running borderline lean with the mods you've installed, and if your warmup enrichment is minimal you might be getting a lean stumble until it's warmed up. Maybe bump it up a couple of units in the appropriate temp ranges and see if it helps (Assuming you have a SERT here).

On an injected bike when it's first started up, the ECM looks at engine temp one time and goes to the appropriate lookup table for enrichment. After that, it's just a timed event I think, and whatever that cell in the enrichment table states for that temp is what's added to your overall AFR. After that the enrichment lessens over time until it reaches zero and runs normally.
 

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Discussion Starter · #3 ·
Thanks Snaps i don't have a SERT but was in the dark as to how the EFI works as far as enrichment when cold. I am going to have to add a SERT or some other EFI device I guess. My bike runs great when this isn't happening. And it is something that just started. So ????
 

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The warmup enrichment settings only last for 90-120 seconds, so if you let it warm up for a minute and are 2 miles from your house, you'll need to look elsewhere.
Plus, if it just started, it's not a setting that doesn't change.
 

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Discussion Starter · #6 ·
MegaGlide said:
The warmup enrichment settings only last for 90-120 seconds, so if you let it warm up for a minute and are 2 miles from your house, you'll need to look elsewhere.
Plus, if it just started, it's not a setting that doesn't change.
I am taking it to the shop today as much as I hate to. I always try to do my own work but this has got me stumped. I do have warrenty so that helps.
 
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