[suzukiguy800]

Everything was fine when put away for winter. Would not start in spring. It would fire with fuel shot into carb,. pulled carb put in new diaphragm and kit .Vacuum fuel pump I thought worked poorly. Temporarily used 1-2 psi electric to test. Now fires and runs with new plugs Old plugs looked fine but changed for good measure.. However.... Idles ok revs up with a little missing. If I opened up it starts to choke out. When shut off after short idle, rear cylinder backfires with a bit of a flame. Possible tight exhaust valve? Any ideas appreciated.....

 

[Skrapiron]

How many miles on the bike? When was the last time you pulled the cylinder heads and checked the gap on the tappets? What did you do to store the bike before putting it up for the winter?

 

[suzukiguy800]

Solved............
Thanks for the reply.. Bike has 12000 on it. I have not pulled heads or done anything with the valves... I did rebuild carb, put fuel stabilizer into tank and drained carb. I kept thinking the fuel pump was bad. So I hooked up the electric pumps Still did not run right, coughed and sputtered. Eventually I ran across my problem. When I started the whole process I took the air cleaner cover and housing off to access the. carb along with couple of stubby lines. I put the electric pump and still ran like crap. The air cleaner housing still off. There in lies the problem. The line that plugs into back of air cleaner housing appx 1/2 inch diameter is a large vacuum line. I stuck my finger over of it and everything
started working fine. As it turned out the vacuum fuel pump was not giving enough volume. The electric is working great.
Goes to show you perceverance pays off and luck don't hurt either. I'm guessing I'll get some questions about what pump I used. It's a 1-2 psi pump I got from amazon It was about $20. I have used this pump on other projects and all still working after couple of years.