Jetting Question / Advice ?

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Aug 15, 2007
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#1
I have a 1984 RM 250 completely restored for Vintage racing. The mods include a DG exhaust, Boyseen reeds and a mild porting job. I upped the main jet from 320 to 340, upped the pilot from 50 to 65 and lowered the clip on the needle one position to richen everything up a little to be on the safe side. The bike will only drive with the choke on and will not take full throttle as it just bogs right out if you increase the throttle too much. It seems to be starving for gas! Should I keep increasing the pilot? Should I put the clip on the bottom position of the needle. I feel that I don't need to increase the main jet as like I said before it won't take full throttle. Any help would be much appreciated.

Thanks
 

_JOE_

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May 10, 2007
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#2
The main jet controls full throttle fuel flow.
 

_JOE_

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#4
Oh. I thought you meant it just wouldn't go at full throttle. I can't imagine it's that lean after going up that much on the pilot. It's not gonna hurt to try though. May wanna check for proper float level, fuel flow, and any obstructions in the carb while you're in there.
 
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Nov 21, 2006
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#5
Check it for a vacuum leak,Spike. It might help your diagnostics to remember that the enrichener(choke)doesn't really do much once the throttle is opened over about 1/8.

Cheers!
Bruce