New Project, New Problems. Advice Please. (1978 KZ750 Twin)

[BornOnThe4th]

I just got a 78 KZ750 twin on a trade and I've got it running, but the issue is that I have to keep the choke halfway open even after it warms up, when I hit the throttle it bogs down and occasionally backfires.

If anyone could help me out with some troubleshooting ideas that would be awesome. Thanks so much in advance!

 

[Aetsh]

Pods? Exhaust? Its a Carb issue

 

[BornOnThe4th]

It has the original box air filter on it as well as the exhaust. Primary jet, maybe?

 

[two-smoker]

I had the same issue on my GT380 when I first got it running. pilot jets are plugged. Maybe mains too. Take the jets out and clean them and see how that works.

 

[arcspeedworks]

+1. You've got clogs in the pilots. Get those carbs off and tear 'em apart (it's not that hard). I soaked mine in a boiling solution of lemon juice and good, old-fashioned water for an hour to loosen up the crud that built up over the years. Flush them out with clean water and compressed air. Don't neglect the float bowls and jets either, they can handle the boil. Just don't put the diaphragms in there.

Should warn you, though. The carbs will come out kind of powdery-looking. Doesn't hurt anything, just looks different.


Also........ I'd check for intake leaks caused by tears in the carb boots on the motor.