chinese ratios

[nathanl]

So after 3 days of obsessively reading this forum I have myself totally confused! I feel like I remember that happytime/goodtime/chinese engines have a built in gear reduction of 4:1? I have searched for confirmation on this but am coming up empty. Maybe my search skills are lacking. My original plan was old weedwacker which could work great for friction, but I want to go with chaindrive so I'm trying to find something that I don't need a jackshaft, 200 tooth cog, or expensive gearbox to run

 

[ocscully]

Here is a thread you might find interesting, specifically the inexpensive reduction gearbox shown in the photos at the top of page 2 http://www.motoredbikes.com/showthread.php?t=12836

You are also correct in your assumption that the Chinese 2-strokes have a built in 4:1 primary reduction.

ocscully

 

[nathanl]

Thanks for that link and information! Yeah, I've found a couple cheaper gearboxes but they still wern't anywhere near 18:1... except for the staton, which is sans cheap. The hunt continues. I'm thinking I may just try a rack mount happytime. Only try to do a little better gas tank than http://www.motoredbikes.com/showthread.php?t=12667 that one!

 

[ocscully]

You don't need 18:1 in a primary gearbox. 4:1 or 5:1 in a primary is more than enough and even the 3:1 could work with a bit of creative fabrication and parts sourcing. The problem with most of the inexpensive reduction boxes available that fit the weedwacker motors is the fact that they reverse the rotation of the motor. The gearbox shown in the thread I linked to does not reverse rotation. The output at the gearbox is CCW just like the motors.

ocscully