I have used all of the following trannys with pocket bike motors. These trannys are interchangeable with all of the engines used. Robin 35, Mitsubishi 43, China Moon 49, GPS 460 They will work on most other small engines under 50cc.
The first is just a simple drive centrifical clutch. It comes with most motors that you buy from racing manufacturers.
Cost $0 when you buy the motor. $15 by itself.
Left side drive.
This is a 3 to 1 gearbox from China. It reverses your drive to the right side.
Cost about $30 from several suppliers.
This is a Staton-Inc approx 8 to 1 gearbox. They have improved this model & it is no longer on their website.
Cost approx $150 up to $225 for the improved 18 to 1. Chrome plating another $80.
right side drive.
This is a China made CVT with a 3 to 1 gearbox & a 2 to 1 belt drive.
Cost $79
right side drive.
A pretty good assortment I thought. I started out just looking for the best all around tranny & found that there is no real place where you can compare the options. I know there are other trannys out there, but here are my observations on these.
#1 Why do you even need a gearbox?
Gear reduction is important to achieve the low end torque you need for a specific weight rider & bike & must be matched to the horse power that you have. I don't have a formula. Trial by error. All of these I use on a jackshaft to further reduce the gears & to change ratios if needed.
#2 How much reduction do you need?
Depends on HP of motor & how much low end power and high end speed that you want.
If you look at the pocket bikes you will notice that most of the fast ones do not use a gearbox. The sprockets on the rear wheels are almost as big as the wheel. Bicycles have a much bigger rear wheel so a sprocket this big is not practical. Therefore you will need to reduce the ratio through a gearbox or a jackshaft or both.
Results:
Straight cent clutch is the most efficient, but you have to run a very large sprocket on your jackshaft.
China 3 to 1 is my favorite. Less size sprocket on jackshaft & lightweight & VERY QUIET.
CVT works well but lose some HP & they WHINE at high speeds. Very nice mounting plate though & solid true rubber mounts. Almost overcomes the WHINNING.
Staton gearbox was the most expensive & looks to be the best built. It is NOISY. Only grease inside it. I will cut my own gasket some day so I can add some real gear oil. It is also Heavy. Mounting is very solid & makes up for some weight. The output gear is nice because you can run reg mc chain. Dave also has been a tremendous help to me as a gear & axle supplier. He has built a few fo showwwre!! ALL my jackshafts have a Staton part or two in them. Thanks Dave.
Tranny comparisons for frame mounted motors
Thanks, Zomby. I needed to know that.
