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Hi there, I recently got a 1981 Yamaha SR250...kinda a barn find, no tank and a bit rough, but was stored relatively inside, so it's not too weathered. I got a tank, took the carb off and cleaned it the best I could, twice now...I can get the bike to start but only in this order:

1) Cover air intake with palm and run starter till I get gas on my hand, then stop starter. Might cough here but usually not.
2) Remove hand, hit starter, she fires up. Wont stay started, stalls quick.
3) Before it stalls, put hand back over air intake, adjust position of fingers to restrict or increase airflow. I can keep this going indefinitely. Can throttle up, sometimes that will bog the engine, sometimes not, depends on how good I control the air flow with my fingers over the intake.

I've had the carb off twice, seems like all the ports are open...Any ideas? I'm going to take it off and try cleaning it again. I'll keep you posted! Thanks in advance for any info you can offer. God I hope it's not a vacuum leak.
 

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Thanks for the reply Dodsfall, I cant find any spot on that carb to adjust anything besides the throttle stop adjustment screw. There is another screw behind the throttle arm...is that it?
 

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Discussion Starter #4
I must have missed something...the third carb clean did the trick. Found a bad spark plug wire also, after I swapped that, she started right up! So nice to be back on a bike again, it's been a while! This little 250 sounds great and has nice bit of zip.

She runs so nice, but I'm getting oil blowing out the crank vent tube...alot! I read it might be a pressure relief valve or clogged oil strain screen. Will drop the pan and clean and see what that does. Cheers!
 

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Excess oil from the crank case vent usually means there was too much oil added at one point and the case is over-full.
 

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The mixture screw is often hidden beneath a plug or otherwise obscured. If you can't see it, that probably means it's never been tampered with. I like to remove them when soaking a carb, just to make sure there isn't any gunk getting trapped in there.
 

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Discussion Starter #7
Excess oil from the crank case vent usually means there was too much oil added at one point and the case is over-full.
I changed the oil just before I got the properly cleaned carb on last night...when I drained it there was barely anything in it. I got more out of the filter than out of the bike! The spec says its capacity is like 1.4 quarts...I only added 1 quart as it was all I had. I imagine I lost quite a bit of that. I'm going to change it again today after work I'll let you know. Thanks again for the advice!
 

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Discussion Starter #8
Dod's what do you clean your oil messes with? The back end of the bike is pretty slick...including the rear wheel! I'm going to try Dawn to start I guess. I'd link a pic to the ugly beast but I'm 11 posts shy of being able to share ;) Cya this afternoon!
 
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