Burned up GY6 Questions By 95civicsi (Read 2,922 times)

[95civicsi]

Valve adjustment was off on the intake side. It cranks now but not easily. After it gets going it bogs down when you open the throttle up. While riding, it backfires heavily when you open the throttle. Max speed is about 15mph.

[Bashan]

Backfiring and bogging under load can be a few things. It usually means it's too lean. Check your A/F screw and make sure it's 2 1/2 out. Also, make sure the exhaust is tight and sealed on the head...this is important. If the jets are clogged it can cause a lean situation. It won't be fuel delivery, that just fills the bowl and the bike will stall when the carb runs dry. Backfiring can also be the coil, I know you checked that, I'm just saying. An intake leak or vac leak can cause a lean condition, check your intake manifold and hoses, same with airbox side leak. Rich

[sprocket]

I think the CDI is defective, if the voltage measurement you gave are accurate.

Probably a very weak or slow spark..it will act just like you describe...

[95civicsi]

The intake elbow has a crack in it. I'm replacing it tomorrow. I'll clean the carb while I'm at it.

[sprocket]

Good find...

[95civicsi]

The carb was very clean, looked like it was almost new. The crack in the manifold went across the top from one mount to the other. Looks like this is a common problem.

[Alleyoop]

What you can do to fix that problem from happening again is Support the other end of the Carb so that it does not bounce up and down.
Alleyoop

[95civicsi]

I changed the elbow. It won't get above idle. As soon as you open the throttle up, even with the back tire off the ground, it boggs down. I'm going to recheck my timing and the valve adjustment. The A/F screw is at 2 1/2 out and no adjustment seems to change the idle speed. I'll also recheck my voltages from the cdi.

[95civicsi]

Quick update - read another thread earlier that may explain my problem. I didn't realize my air filter needed to be on to test the engine. I've been testing without it.