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2-Stroke Gearbox??


Active Member
Mar 19, 2008
The other day I was riding home, and I didn't move the throttle from where it originally was... but the engine kept revving, but the driveshaft wasn't spinning. I had to walk it home because I had the pedal chain off at that time.

I called the guy I got the bike from & I told him I thought it was the clutch. He said, no... it would have died. I agreed at that point, and he said the only thing it could be is the gearbox.

I didn't realize these single gear 2-strokes had gearboxes... I thought it was just a clutch housing.

Either way, the bike just magically started working a day or two later... but I'm still trying to figure out why the driveshaft wouldn't spin when the engine was definitely revving...


Jan 6, 2008
Routine monthly clutch maintenance.

Is this motor a Happy time with a clutch
Check and Grease your clutch cable.
Check the clutch adjustment, and for free travel of the cable.
I grease the sprocket side clutch linkage( the rod where the brass cable end attaches) , the little rod, the little ball.
Under the carb is a bolt with a cable running through it.
The bolt that holds the end of the clutch cable needs to be removed and some grease forced into this hole.
This is where the clutch spring lives.
Use a grease gun if possible, if not force a fingertip of grease at a time into this space.
Replace the bolt. Reinstall the sprocket cover.
Now on the other side of the engine remove the 5 screws attaching the clutch cover . place a bean sized blob of grease on the place where the small gear, and the large gear meet.

Tedious and boring to do.
Smooth running is assured.
Unless something all ready got dry and siezed.

Or a Rack mount with an automatic clutch.
Look in rack mount section.
Did you drive through a puddle??

Is your clutch slipping like crazy when hot and ok when cold. Adjust or replace your clutch.
Did you drive through a puddle??
Last edited:


Active Member
Mar 19, 2008
Terribly sorry, this isn't a Happy Time. It's a 33cc Chinese engine with centrifugal clutch. No clutch cable for me to pull.


I think your instinct was right- it was the clutch. For sime reason, when you revved it, the shoes were not engaging.

There are two ways the clutch can fail- in the engaged position- meaning it will not disengage and will die at low rpm; and in the not engaged position, meaning it will rev and not go anywhere. I would check the shafts on which the shoes pivot to make sure they pivot freely and lubricate if necessary.

One other thing I thought of, how is the key on crankshaft. If it is sheered- it may work OK when cold and not under resistence, but when it heats up, it may allow slippage.