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rusjack
06-08-2010, 4:58 PM
the bike im having a hard time with is an 81 yamaha SR250. top end rebuild, exhaust that is just 1 1/2" straight pipe for now, and a carb that was cleaned before I got it, and re-checked by myself.

when i first started this bike this year i put in fresh gas, and didnt know the idle adjust was set so the bike was at mid-throttle. bike started up right away, high rpms and i killed it. did that a few times before setting the idle adjust so it was putting along properly... at this point it started, putted and died.

next day, recharged the battery and the only way i can get it to start is by putting my hand over the back of the carb until i feel gas/some suction on my hand, and it starts up... but the only way i can keep it running is by giving it gas on the throttle over and over... when i stop, it dies.

too rich? too lean? is there something basic im missing? (other than an air filter)

DaveyRiot
06-09-2010, 9:40 AM
if you opened the exhaust up like that you probably need to rejet the carb. PLus are you starting the bike with the choke on or off?

VJ
06-09-2010, 10:47 AM
Most likely way too lean. You're running wide open where restriction was designed to be. You'll need to rejet or add an air filter and baffle to the exhaust or "D" all the above.

DaveyRiot
06-09-2010, 6:11 PM
a good start is to screw the idle mixture screw all the way in and then back it out 2 and 1/2 turns. buy a bunch of plugs cause you're gonna have a lot of plug choppin to do!

DaveyRiot
06-11-2010, 1:34 AM
up your pilot jet 2 sizes and turn the idle mixture screw (above the butterfly) out 3 turns.