Post by sk8r on Jun 20, 2013 20:07:42 GMT -5
Hey, Tom: GY6 Carburetor Vacuum Leaks Intake
I got your timely message this morning and jumped right on it.
From what you said I assumed vacuum leak right off the top.
I disconnected and removed the whole intake manifold. There is an o-ring seal embedded in the metal on the engine side, and what looks like some kind of shellac to hold it in. Potential leak #1. Extract o-ring, dissolve shellac, re-seat o-ring, reattach intake to engine.
Intake manifold has 2 vacuum nipples venting into main intake chamber. One needs to be plugged off, the other vents out to the fuel valve under the gas tank. Rubber hoses, spring clipped to nipples. Potential leaks #2, 3, 4, and plug #5. I replaced spring clips with cable ties (tighter) and inserted a golf tee into hose for a plug.
Reattach intake manifold to carb.
Start engine, let it warm up. Initial idle screw setting: back off to flush, then turn CW 1-1/2 turns as starting point.
After this I followed your directions to a T. Worked great. Before fixing leaks, I couldn't get any kind of constant idle. Now I could do A/F and idle tweaks and observe effects.
* Warning * if you leave your machine on stand and idling long enough, the auto choke may take over and start doing some weird things with the idle **
This happened to me, but I decided to take a test drive in spite of it, and I'm glad I did, because my deceleration symptom was gone. I anticipate some minor tweaking over the next few days, but thanks to you it's pretty close now.
Thank you for your suggestions, it was very helpful.
I hope I have supplied enough detail to help others with similar problems.
Craig
I got your timely message this morning and jumped right on it.
From what you said I assumed vacuum leak right off the top.
I disconnected and removed the whole intake manifold. There is an o-ring seal embedded in the metal on the engine side, and what looks like some kind of shellac to hold it in. Potential leak #1. Extract o-ring, dissolve shellac, re-seat o-ring, reattach intake to engine.
Intake manifold has 2 vacuum nipples venting into main intake chamber. One needs to be plugged off, the other vents out to the fuel valve under the gas tank. Rubber hoses, spring clipped to nipples. Potential leaks #2, 3, 4, and plug #5. I replaced spring clips with cable ties (tighter) and inserted a golf tee into hose for a plug.
Reattach intake manifold to carb.
Start engine, let it warm up. Initial idle screw setting: back off to flush, then turn CW 1-1/2 turns as starting point.
After this I followed your directions to a T. Worked great. Before fixing leaks, I couldn't get any kind of constant idle. Now I could do A/F and idle tweaks and observe effects.
* Warning * if you leave your machine on stand and idling long enough, the auto choke may take over and start doing some weird things with the idle **
This happened to me, but I decided to take a test drive in spite of it, and I'm glad I did, because my deceleration symptom was gone. I anticipate some minor tweaking over the next few days, but thanks to you it's pretty close now.
Thank you for your suggestions, it was very helpful.
I hope I have supplied enough detail to help others with similar problems.
Craig