Since i have put a thunderheader on my Shovelhead, i cant get rid of a really bad stutter that happens every time i shift. The bike had an S&amp\\;S E i have the jetting good. If i take it off and put different exhaust on it the stutter is gone. Does anyone have any places to look, or is there something i can to to the thunderheader to cure this. Thanks

 

Have you tried calling Thunderheader and explaining the problem to them to get their take on it?

 

I tried calling them but they wont give you the time of day if you arent a dealer.

 

Are there baffle combinations you can try? I see from their website that they have an anti-reversion feature built into their product for Shovelheads. Did you get your set-up new, with paperwork about tuning their system? If you got it from a dealer of theirs, will they call 'em and ask for help. How about checking with an independent shop about what might be done?

 

I did buy it new, but dont remember any paperwork with it. I have it at a local indy right now, and hopefully he can figure something out.

 

So when you are sitting at a stop, idling, you can rev it up with no problem?
What carb are you running?
Since it behaves okay with a different exhaust system, I wonder if there is a reversion problem.
I imagine you shift gears at about the same rpm everytime (or most times anyway) which makes me think that you are experiencing reversion at that rpm that really shows itself when you close the throttle slighly as you shift and then reopen it and the reversion is interupting the intake flow causing it to go lean. Does it pop backwards through the carb when it stutters?
With the engine off, does the accelerator pump work throughout the entire stroke of the throttle...nice smooth, even, uninterupted stream?

 

Yes when im sitting still it will rev up perfect. Its a super E carb. The accelerator pump is working as it should also. I have been over this thing a million times tryin to find the problem. I was wondering if it was a reversion problem. I appreciate the thought you are putting into this. Is there a way to diagnose a reversion problem.

 

Try riding the bike with the air cleaner off to see if fuel is spitting backwards out of the carb, if you have a safe spot to do this. Reversion will push the air fuel mix backwards.

 

There is an old trick of putting an eyebolt in the exhaust that can be turned to "tune" the reversion out of it. It would require drilling on your new exhaust (I would not want to drill my new exhaust).
Torque cones may do the trick.
Talk to the indy about solutions if they think it's reversion.

 

I did notice fuel spraying out of the carb the other day, but didnt think anything of it. I think my next step will be trying torque cone. Thanks for the advice