[/font=Arial][/size=6][black][/black]What about fuel filter or fuel pump. Could they cause this? If so, how to test them? I cleaned the carbs last night - they looked clean. Hope to put it back together today and test.
[/font=Arial][/size=6][black][/black]Haven't noticed any smoke when it backfires. Starting cold, I flip the choke on full, it starts on the first pull, after about 30 seconds I cut choke back to half, after about another 30 seconds to a minute, I turn choke off. It runs great - full power - for maybe a minute or two, then a couple loud backfires and stall. It can only be started then with choke on (halfway works) - won't even fire with no choke. If I get it started again, it's the same sequence over and over - runs for a short time, backfires and dies.
I have the carbs out now. Stock jetting is 160 (main jet), 45 (pilot). I have 180 (main jet), and 40 (pilot). I'm told these jets should be fine - that stock was a little lean. Carbs looked clean, but I soaked in carb cleaner anyway. Floats appeared to be functioning. The choke valves were a little gunky (looks like maybe some locktite?) A guy at a local shop thinks choke is sticking, then cutting off when it backfires? Doesn't make sense to me why it would need to be choked to restart though if choke was stuck. I plan on cleaning the choke valves, lubing cables, put it all together and fire it up again this evening. What's a good way to check fuel pump? I'll also replace the fuel filter.
Well the backfires would be because not all the fuel is being used, so it builds up in the exaust pipes then when it ignites in the pipes, in stalls the sled. So I would be checking out you plugs and the strenght of your spark...
[/font=Arial][/size=6][black][/black]I found gunk in the fuel screw of one carb. The choke valves were also caked up a bit. After cleaning the carbs it seems to run fine. I warmed it up for a couple minutes then rode it around the block - ran good, no backfiring.
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