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Post by sk8r on Jun 20, 2013 7:51:06 GMT -5
If anyone out there can help me.
I have a brand new Chinese scoot & new carb with fuel mix accessible. While trying to set up the carb I realized that deceleration is not happening.
Specifically: throttle up, purrs nicely, but throttle back down it takes a very long time to return to idle, if at all.
This occurs while stationary OR while moving, and MUST use the brake to slow the engine down. (GY6 carb, 50cc) I had the same symptoms with the former carb. Is this a vacuum issue or a carb tweak?
Please advise.
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Post by jerseyboy on Jun 20, 2013 8:32:07 GMT -5
Make sure your throttle cable is all lubed up and returning all the way,check this at the carb,,make sure it snaps back nice.Also make sure all the vac lines are in good shape,,and check for air leaks around the front of carb and intake,,To set A/F warm up motor,,then screw in CW until motor starts to die(sputter)then back it out CCW until RPM reaches its highest point,,dont go any farther,,then go CW 1/8th turn,,after that reset the idle to where the back tire wont spin on center stand,,give the motor a quick blip of throttle to see how its taking the fuel.
Hope that helps..
BTW-I had to remove a small rubber boot from the end of my cable by carb as it was hanging up causing this same problem you speak of,,check it out.
Tom
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Post by pmatulew on Jun 20, 2013 11:48:48 GMT -5
Low speed circuit too lean or not working. Idle speed adjustment set high to compensate and keep fuel flowing from the main jet. So it's not transitioning back down to the idle jet. DX Check that the slide is free. Check for air leaks. Check that the idle jet is clear. Check the float height. Then start twisting the dials until it behaves correctly.
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Post by shalomrider on Jun 20, 2013 18:04:58 GMT -5
howdy, on a carburated car that was often caused by the carburator base gasket being loose or damaged?
lotsa miles and smiles to ya
ken
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New Rider
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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
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