Correct jetting

1 reply to this topic
  • dirtfanatic50

Posted August 05, 2009 - 05:29 AM


I seem to recall reading on here a while back, but can't find it now, that if a bike is jetted correctly, you will need to use the choke for a cold engine, & that it will take a little time to warm up. That was the case until I added an aftermarket exhaust, & re jetted. 05 Wr 450F ,FMF powercore 4 can & SX powerbomb header, re jetted to 168 main (165 stock), 48 pilot (45 stock)
GYT-r ais kit needle on 4th clip. Running slightly rich so moved the clip up one notch. Bike starts extremely easy now without need for choke. Is there anything else I need to change ?

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  • WR_Dave

Posted August 05, 2009 - 01:03 PM


At start up the carb is only using the pilot circuit, the choke enriches this running condition with the engine cold. So if you no longer need the choke it is already rich enough to run when cold. I would say that you should drop back to the original pilot jet or even try one that is smaller. The bike may start and run , but after it is warmed up it wil more than likely be too rich off the bottom the way you have it now. JMHO -- WR Dave


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