1980 sr250 dies with the slightest amount of throttle

Hows it going guys? I have a 1980 sr250 that has been giving me nothing but a headache. Im hoping someone can help me. Im 23 years old and this motorcycle belonged to my grandfather who now passed away. The bike was passed down to my father. The bikes has not ran since 2001. A couple months ago, i decided i would go outside and work on this bike and see if i could get it going. A thorough carb cleaning, a semi decent cleaning of the gastank, and a new battery, and the bike fired up. My father was thrilled. I turned the choke off and grabbed some throttle and the bike died. My father then reminded me that ge had spent a countless number of days trying to fix the bike and he had givin up. He just couldnt figure it out. Me being the ignorant son that i am, felt like i was going to prove to him that i could get it going. Now for anybody thats going to say my pilot jet is the culprit, i have cleaned this carburetor about 8 times. I took out each jet, o ring, and used carb cleaner and blew the circuts out with compressed air. I am absolutely positive that my pilot jet and main jet are mecanically tip top. What could be causing this condition? This bike is consuming me and i will not stop untill i figure this out! Thank you for your help!

Also, one day, i went outside to investigate a little ferther and found out that mice had made a nest in the air filter. I ordered a new air filter and cleaned out the box. There is a new spark plug, theres fresh oil, and i also got a semi new diaphragm for the carb. I also noticed a significant amount of rust in the gastank which i cleaned out. I have a fuel filter coming in the mail. The carburetor also has a new needle valve, a new float, and a new pilot jet. Thanks again for reading


Check your tailpipe / silencer isnt blocked up

S.O.A.N.Z thank you so much! I will keep you posted tomorrow evening!

So i pulled the exaust off yesterday and everything seems to be clear. I just dont know what could be causing this. The bike has 2000 miles on it. It will start right up with choke, but the SECOND i turn choke off or even breathe on the throttle, the bike dies. Im at a loss for words.

did you check your valve clearances ?

S.O.A.N.Z i spent the day working on the sr250. I decided i would check the valve clearance. The valves were off a bit so i adjusted them to spec. My feeler gauges are very old so i had trouble finding out which ones to use. I think i need a metric guage. Anyway, the valves seemed a little tight. I loosend them a bit and tried starting the bike. The symptoms were the same. I started giving the bike gas and everytime i touched the throttle, the bike died. It got me thinking about how this really is the classic pilot jet culprit. I know i said i was positive that i cleaned the pilot circut, but i decided it couldnt hurt to have a second look. I pulled the carb off and removed the new pilot jet that i installed. I followed the circut up the carburetor and realised that the circut splits off into 2 directions up by the diaphragm. I removed the diaphragm cover and then realised that there is a secondary pilot jet. Under that jet, there was crud and crystalised gas lodged in there. I used some wire and compressed air to get it out. I cleaned the carburetor quickly, (not thoroughly) and put it all back together. I started the bike, and grabbed some throttle. Im proud to say that everything operated ALMOST as it should. The throttle was responsive, and it wouldnt stall. However, the bike wouldnt really idle. So i believe i figured out the issue. Heres my plan. Im going to ultrasonic clean the carburetor and make sure that it is spotless. Then, i am going to make sure that every ounce of rust is out of that gas tank. After that, i will order some sea foam, a new fuel line, and i will install my new fuel filter. Im thinking the bike will be as good as new after this. Thank you so much for all the clues and responding. I hope this info will help someone that is having the same issue! Happy riding

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