Serious over rev!

[John Izak]

My 48cc over revs when I de clutch with throttle s

hut down. Any ideas? This just started on last ride.

 

[Al.Fisherman]

Check the carburetor piston/cable and make sure it's not sticking. Have you done ANYTHING...ANYTHING to the bike since it ran well. Hold in clutch and pin it. Now move the throttle from idle to full RPM, the throttle should have smooth movement, if not find out where it is binding.

Heck I was camping at Goose Pond a few weeks ago.

 

[motorpsycho]

sounds like the throttle is sticking.
kink in the cable?

 

[arceeguy]

If the throttle isn't sticking, it could be an air leak.
Check where the carb clamps on and the intake gasket. I use some teflon tape around the intake tube to ensure an airtight seal. There is a slight chance that it could be the cylinder base gasket, case half gasket, or crankshaft seals. (rare)

 

[AussieSteve]

You might possibly be having the problem that I had a couple of weeks ago.
If I did up the carb top cap tightly, the slide was jamming fully open.
I put a fibre washer in the top cap to cure the problem.
Al had the same problem and used silicon on the top-cap thread.
See:-
Happytime NT carb Slide Jamming

... Steve

 

[Al.Fisherman]

You might possibly be having the problem that I had a couple of weeks ago.
If I did up the carb top cap tightly, the slide was jamming fully open.
I put a fibre washer in the top cap to cure the problem.
Al had the same problem and used silicon on the top-cap thread.
See:-
Happytime NT carb Slide Jamming

... Steve

Dam* Steve...good memory...You can't tighten the cap too tight, just a tad more then finger tight. Also I installed a "O" ring in the intake. The carburetor intake flange butts up to the "O" ring in the carburetor. Force pressure on the carburetor while sliding it over the intake and tighten.

 

[Chris Crew]

I vote air leak or over-tight cap on the throttle housing.