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.
