Rejetting for exhaust insert

3 replies to this topic
  • BergRyder

Posted August 29, 2005 - 10:01 PM


Are there any general rules of thumb for jetting when putting in a more restrictive tail pipe insert?
I have an 01 426 Supermoto with a Yoshimura RS-3 full pipe that I race without any inserts and the bike runs great. For an upcoming race the sound level is 96 decibels, which should be achievable with the medium Yoshi insert. I have tried the insert with the current carb setup and the bike runs very badly, what do I need to adjust/change?

  • bg10459

Posted August 30, 2005 - 07:04 AM


Drop the main jet 1 size and see if you can re-tune the pilot circuit with the screw. If not, drop the pilot also.

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  • BergRyder

Posted September 06, 2005 - 09:04 PM


I ended up dropping the main from a 175 to a 172,
dropped the pilot jet from a 48 to a 40, and raised the needle one clip. The power delivery is smooth, no popping on deceleration, sweet :D

  • clark4131

Posted September 06, 2005 - 09:30 PM


With a 40 Pilot, you may be WAY too lean unless you're in the 10,000' range and then it still might be a stretch. I'm at 5000' and I'm running a 45 with the JD Red #5. I'd be willing to bet that the 172 Main is compensating for the Pilot circuit with a bit of overlap. You may be running well, but it sounds off and is likely having some effect on your valves and such that you can't detect...SC


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