I have a 2005 636. Whenever I accelerate from a stop the motor bogs down, kind of bucks and jumps erratically from 1000-3500 rpms. I have to give it a bit more gas and work the clutch just to keep it from stalling. Once it's past 3500rpms it runs fine. On colder days it doesn't do it as much, but on hot summer days, it's guaranteed to do it. The only mods I have on the bike are a K&N air filter and Yoshimura RS5 exhaust. I took it to two different dealerships and they cannot find the problem. One dealership said it was the throttle position sensor and replaced it. This did not fix the problem. Please help.

 

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Welcome to KF

I would assume that the plugs, wires, coils were checked by the dealers. Any codes showing on the dash? Any starting issues? The engine only jumps under a load or all of the time?

 

The engine only does this under a load. If I put it in neutral, it'll rev straight through with no problems at all. There are no starting issues. I am not seeing any codes on the dash. The FI light is on, however, I believe it's from the aftermarket exhaust and not having an exhaust servo mod. Not a hundred percent though. If there were codes, where exactly would they be?

 

thanks, by the way

 

yes the FI light is from not having the servo block...should have come with the pipe...still can get one...more than likely the problem is fuel/air mixture since you have swapped out both the stock air filter and pipe...a PC3 or equivalent will smooth out your engine...

 

As Odi mentioned on the PC3 or equiv, you need some tuning.

Pretty much key words for a tune and PC3 or equiv

 

I'll look into the tuning. However, it has never done this before. I ran the bike for two years straight with the yosh and k&n with no problems. Just started happening here recently. If I'm not mistaken, the dealership said they tuned the bike with a 'yosh box' when I first had it installed. Could it possibly have gone back to default setting?

 

I have not done a "yosh tuning" so am not sure.