Jetting questions on my 1999 YZ400F


1 reply to this topic
  • PatrickM

Posted December 05, 2007 - 03:03 AM

#1

I have a 1999 YZ400F and I want to change the exhaust from the original FMF "Q" muffler to a FMF power core 4 Muffler.

When I last had the carb worked on it was jetted perfectly to the FMF "Q" muffler.

I was wondering if the jetting needs to be changed or will previous jetting work?

I dont know what jetting is in there right now becuase my mechanic did not keep a record of what went in there when they fixed the carb

Do i need to know and how would i find out????


Thanks for all of your help!!!


Patrick M.

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • 642MX

Posted December 05, 2007 - 06:14 PM

#2

I have a 1999 YZ400F and I want to change the exhaust from the original FMF "Q" muffler to a FMF power core 4 Muffler.

When I last had the carb worked on it was jetted perfectly to the FMF "Q" muffler.

I was wondering if the jetting needs to be changed or will previous jetting work?

I dont know what jetting is in there right now becuase my mechanic did not keep a record of what went in there when they fixed the carb

Do i need to know and how would i find out????


Thanks for all of your help!!!


Patrick M.


Jetting is mostly trial and error. Put your pipe on and see how it runs.





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