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Need jetting specs for 07YZ125 w/PC pipe, silencer, RAD valve

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 I just changed from the stock exhaust to a PC pipe, silencer and Boyesen RAD valve.on my '07 YZ125. 

Does anyone have jetting recommendations for this setup at sea level, 60-75 deg F? 

Engine is stock otherwise ... thanks! 

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  PC says keep the 410 stock mainjet, use a 35 pilot (stock =40) and move the clip from the 4th groove from top to third; jetting does not change with reed valve upgrades. 


 Boyesen says if the RAD valve is added and the stock pipe is used, drop the main to a 380 or 390. If the PC exhaust is used, go up to a 400 mainjet from there, since the PC exhaust needs more fuel.  


 JD jetting says jetting does not need to be changed when changing exhausts, since pipes only move the power around the powerband, depending on which pipe is used. 


 I guess I'll go with the PC jetting to start and keep an eye on the plug color and err on th.e rich side ... 

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Jetting I would go with Boyesen recommendations and take the PC pipe and silencer off and put the stock system back on.


PC pipe is horrible compared to the stock system.


I think stock even better then the FMF but that is only my opinion by riding no dyno to prove.(plus the stock pipe does not stick out as much as the ffmf fatty and burn your gear and boots)


Owned 05,06,08,10 and now another 06 and stock was always better than PC and feels stronger than FMF. Derick from harris performance put a dyno up recently and the FMF fatty showed more power on the dyno but I always still preferred the stock pipe and silencer.


or ride a cr125 ,rm125,kx125 and even your PC pipe will feel awesome(personal experience).

Edited by qwert321

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