Hello everyone,
I am looking to build a drag type mini bike and I have loads of questions here they are.
1. need to know what size rear wheel and tire to run, wanting to run a slick on back.
2. what size back sprocket and chain size do I need to run?
3. I am going to run the predator hemi engine do I need to run a convertor clutch or just plain centrifugal clutch?
4.what is the best brake to run on the rear, I am leaning toward a disc instead of drum type.
and last where is the best place to look for the above parts?
Thanks for any and all help.
Dave
This is all my personal opinion
1) the lighter the rear tire/wheel, the less force it takes to rotate it. Smaller wheels will let the engine rev up faster. 5" are ok, but 6" are good too. Any bigger and you will be at a disadvantage i think
2) chain size isnt too important, as long as clutch, and sprocket size are good. most run #35 chain, but you will need a tensioner. If you run 40/41/420 chain, you wont have as many issues with flinging the chain. #35 gives you more clutch options. You could even run #35 to a jackshaft in, and #420 from jackshaft out to rear wheel. A slick tire meant for go kart racing with an aluminum (douglas) type rim with a hub for split sprockets would be a good way to go because they are all light and you can swap out rear sprockets easily. You would run it to a really short 'go kart' axle.
3) torque converters have won drag races (330') on a hemi predator. engagement was set to 4000 rpm with special springs. With that said, torque converters are the exception, not the rule. You will get higher rpms on a clutch, and you dont get as much parasitic drag from a clutch once it engages compared to a torque converter. If you are actually going to make a drag bike, you need to get a disc clutch (racing clutch) that engages at or slightly above the engines peak torque output. if you cant get the $$ for a race clutch (e.g. bully or similiar), at least get a decent GE Noram or something like that, a high end centrifugal clutch.
4) hydraulic disc brake is the only way to go here. You dont want to be going 60 mph and have a brake band.
a few good places include BMIkarts, gopowersports, ebay. etc. Yoiu can get the brake setup cheap on ebay, BMI specializes more in race kart stuff. Gopowersports has all around good stuff. NR racing and ARC racing would have the goodies for your engine.
what are you going to do to your engine?
