| Author | Message | ||
     Vortec57 |
Working on this bike for a friend and it has me stumped. it is a 1982 Yamaha Seca 550 (XJ550RJ) When I brought the bike it it had a HUGE stumble off low RPM and ocasionally died like it ran out of fuel, but was full. Plugs were dark brown/black and wet when i started. 3 pilot jets were totally plugged and carbs generally gummy. I cleaned the jets and carbs (did not do full clean, just from outside and in float bowl area) replaced plugs and changed oil in it. Now I have it back together and the low RPM bog is much less noticeable. The problem is once it runs for a while and gets up to full operating temperature it dies. Sometimes turning on the choke helps, but not always. The plugs have about 15 mins of runtime on them and now they are pretty white. I did not change any fuel settings, just cleaned up jets and bowls and put it back together. running factory exhaust and factory air filter. Spark is strong when cold and when warm. Any suggestions on what to look at next? Trying to keep this on as small of a budget as possible. Some of you may remember this is the bike for the cute girl I helped along the road. well, she needs to get riding again  | ||
| Just_ziptab |
Does fuel flow freely if you pull the lines off the carbs?....and does it have a vacuum operated fuel petcock? | ||
| Mnrider |
Test the compression and clean the carbs again,you'll have to take all the jets out and clean all the passages. | ||
| Tom_b |
If the plugs are white it is running lean. I would also pull the carbs and clean again. I used to own a 550 maxim which is pretty much the same bike. Had carb issues, took a couple of teardowns to get cleaned as i always tried the easy way first. The engines are pretty bullet proof, i would be surprise it had bad valve or compression problem | ||
| Nik |
Clean the carbs completely. replace the jets even. check the valve clearances and float heights if its running better when cold also. |
