Greetings All,
I recently picked up 3 apollo sportrax 125cc quads, for my kids. While each one of the quads has had its share of difficulties, I have been able to turn a wrench and get things working again. However I recently encountered a major difficulty with one of them.

Engine starts right up, but when you put it into gear nothing, well it will go in reverse ever so slightly.

* I can feel/hear the bike going into gear, so not a shift problem
* When I lift the rear end(tires off the ground) shift into forward, the wheels move forward as expected, same with reverse. If bike is on ground, this does not occur. Almost like there is not enough torque to move the bike. Could this be a clutch issue?
* I tired adjusting the clutch, with no change in results.

I was wondering if anyone could point me in the right direction on this, im leaning towards clutch but its hard to say.

Does anyone know what model engine are on those things? Is there an engine manual/diagram that anyone could share.

 

Just Googled it and it looks like a stretched Honda Cub engine, there seems to be a variety of transmissions fitted to these, and I have never found an answer as to how the auto versions work. Check the chain drive to the rear end first, but it is probably going to be a clutch problem of some sort. Most quads have two main clutches, a lawnmower style centrifugal, for setting off from a stop and a conventional multiplate motorcycle clutch, which is operated by the first part of the gear pedal's travel. However some of those "Cub" based engines are different.