I'm at my wits end with my engine!
I have a 1982 XS650 with BS34 carbs. I rebuilt the engine early last year (Jan 2009), but could never get it to run correctly, so it sat in my garage for a whole year. After I rebuilt the engine I couldn't get it started, so I rechecked the timing, and found that I was off two teeth on the cam gear, so after I reset the timing, the engine started up and idled, but it popped and backfired. When I say it popped, I mean it backfired through the carb. I took the carbs apart, cleaned them, and did a basic rebuild on them. This helped out some, but it still backfired and popped.
I checked the timing with a timing light, and it's right on. The jets are standard, and the engine ran good before the rebuild. I thought that it might be an air leak at the carb boots, so I bought new ones from Mike's XS, and installed them today.
After getting the engine started this afternoon, I had to use the choke for a long time before it would idle with out it. I adjusted the idle mixture screws using the dead cylinder method, but I haven't had a chance to check the synchronization of the carbs. Now the engine idles roughly, and sometimes it idles at 2000 rpm, 1000 rpm, 3000 rpm. Sometimes it will idle at 3000 rpm, so I'll rev the engine and it will go down to 1000 rpm idle, then I'll rev again and it will go up to 2000 rpm and hang there for a while, comes down to 1000 rpm and then dies.
Also, sometimes the throttle is very responsive, I'll roll on the throttle and it quickly revs up, and other times I'll roll the throttle quickly and the engine will sputter and die.
I'm lost here. I'm mostly a fuel injector guy, so carbs are dark and scary. Can any one give me guidance on where to start diagnosing this problem?
I have a 1982 XS650 with BS34 carbs. I rebuilt the engine early last year (Jan 2009), but could never get it to run correctly, so it sat in my garage for a whole year. After I rebuilt the engine I couldn't get it started, so I rechecked the timing, and found that I was off two teeth on the cam gear, so after I reset the timing, the engine started up and idled, but it popped and backfired. When I say it popped, I mean it backfired through the carb. I took the carbs apart, cleaned them, and did a basic rebuild on them. This helped out some, but it still backfired and popped.
I checked the timing with a timing light, and it's right on. The jets are standard, and the engine ran good before the rebuild. I thought that it might be an air leak at the carb boots, so I bought new ones from Mike's XS, and installed them today.
After getting the engine started this afternoon, I had to use the choke for a long time before it would idle with out it. I adjusted the idle mixture screws using the dead cylinder method, but I haven't had a chance to check the synchronization of the carbs. Now the engine idles roughly, and sometimes it idles at 2000 rpm, 1000 rpm, 3000 rpm. Sometimes it will idle at 3000 rpm, so I'll rev the engine and it will go down to 1000 rpm idle, then I'll rev again and it will go up to 2000 rpm and hang there for a while, comes down to 1000 rpm and then dies.
Also, sometimes the throttle is very responsive, I'll roll on the throttle and it quickly revs up, and other times I'll roll the throttle quickly and the engine will sputter and die.
I'm lost here. I'm mostly a fuel injector guy, so carbs are dark and scary. Can any one give me guidance on where to start diagnosing this problem?