New to the forum

[AceEngineer]

Just registered on this forum up today
I'm in the process of building a shifter kart from a old kart chassis that I built years ago. Not raceable, made just for fun. I've got an old Kawi KE-175 2 cycle rotary valve motorcycle engine left over from my dirt biking days that still runs good so that is the engine and tranny I plan to use. Tore out the McCulloch MC-101D racing engine that was in the kart (too finicky for a fun kart) and I am in the process of fitting the new engine. Because of the size of the chassis, I plan on mounting the engine backwards behind the seat. This will solve a lot of location problems for me, putting the exhaust facing backwards and the kick starter where it will be useable (just in front of the left rear wheel) and hopefully better cooling. Being new to shifter karts (I've never even seen one close up), I was wondering how do people typically handle the clutch and shifter. A third pedal and a hand shifter is my first thought. An electric or pneumatic/air tank shifter with a hand clutch also came to mind. Any experienced drivers out there that can give me an opinion on which would be easier to drive, or is there a better way? Another thing I was wondering was, if anybody has an experience with an air cooled motor. The dirt bike engine has massive fins and the head will hang off the back, so I am hoping that I will not have to add a fan. What have others done about this problem? Also, does anybody know if there is still a market for the old McCulloch engine? I have two 101D's and a slew of parts that I would hate to throw out, in the old days they were quite valuable. If you look close at the photos you can see that I have a differential in the rear axle. I have figured out a way to make it easiely lockable and plan to add that feature. The kart also has hydralic brakes all around made from motor cycle parts, so the braking is quite powerful, easy to lock them up.

 

[fowler]

i figure u will just flip the diff to get the right direction

a hnad clutch on the shifter is the hmost common way but i prefer a third pedal

 

[AceEngineer]

Flipping the diff won't reverse the direction. The golf cart diff (from Comet) is driven by a sprocket on the pumpkin. The rear brake disc is also fastened to the diff pumpkin. I have designed a small single stage 1:1 gear box to reverse the direction. The new engine puts out a max of 17 hp so I designed the gearbox for about 25 hp. With a lightened aluminum case the gearbox shouldn't weigh more than about 4-5 lbs. Single stage spur gears in roller bearings running in oil. Take a close look at the photos below, you can see the diff pumpkin in the center of the driven sprocket. I am going to move the diff more to the right, by shortening one axle and lengthening the other to make more room for the new engine. The reversal gear box will replace my original jack shaft right behind the bottom of the seat. The weird way the frame is made in the back is because I had to support stub axles so the diff just floats in the middle. There are two bearings on each stub axle, one is tucked right out at the wheel and one inboard. This removes most of the bending load from the diff bearings. While I have it apart, I am going to make provisions to lock one axle to the diff pumpkin with a clamp-on collar. This will allow me to lock the diff easily in just a few minutes. Should be interesting to compare the driving dynamics between a live axle and an open diff.