I need help with gear size for my f n r rear end.

[fx4stroker]

Hey guys im working on my truggy and have got a few questions. What ive got is a kawasaki mule that now has a motor out of a cb750 and has a kkk k26 turbo off of a audi. It took me forever to get the right jetting with the turbos and carbs but ive got it running good now. Now i need to get my gearing figured out. The F N R rear end in the mule has high and low. In low gear its a 20:1 ratio and in high its 10:1 ratio. Im guessing I did this right but what I did to count the gear ratio was to count how many times I turned the transmission input shaft to get one full turn of the cv axle comming out of the diff. So when I say 10:1 I turned the input shaft 10 times and got one full turn from the rearend output (cv axle). Some one let me know if I did that wrong. The cb 750 has about 60hp from the factory and I have a dyno jet kit in the carbs and two washers under the carb needle to get even more fuel so i really have no idea how much power its pushing now. The turbo is running 9 psi of boost with a wastegate and BOV. I plan on adding a intercooler once I get it moving. Here is the info I found on the transmission for the motor.

Type Five-speed, constant-mesh, multi-plate wet clutch
Primary drive Hy-Vo chain and spur gears, 2.38:1
Final drive # 530 sealed O-ring chain, 2.39:1
Gear ratios, overall (1) 14.40 (2) 10.17 (3) 7.91 (4) 6.59 (5) 5.48

The trans has a 15 tooth sprocket on it now. I dont know if this matters or not but the bike had a 38 tooth sproket on it. I dont need the top speed to be 100mph and I wouldnt want to go that fast on a mule atleast till i redo the suspenion. I was hoping to shoot for maybee a top speed of 60 mph in high gear. What size sprokets do you think I should go with? Also the transmission has a 7/8 shaft and if you could point me in the best direction to find a good sproket setup for the rear I would sure appreicate it. Here is a pic of the rear end before I got the motor in it so yall can get a idea of what im doing. I will try and get some pics of the mule with the motor in it tonight and post them.

Oh and thanks!

[bdkw1]

10-1 is a pretty steep reduction. I would go for a 15T rear sprocket set-up.

McMaster Carr has bushing lock drive sprockets for a 7/8 shaft and 15T sprockets.

[fx4stroker]

Originally Posted by bdkw1

10-1 is a pretty steep reduction. I would go for a 15T rear sprocket set-up.

McMaster Carr has bushing lock drive sprockets for a 7/8 shaft and 15T sprockets.

Really a 15tooth thats tiny. I dont know a thing about gearing I guess im just used to seeing these huge sprokets on the rear end of these mini rails. Is there a way to figure out what my speed through the gears would be? Thanks for the input.

[fx4stroker]

Originally Posted by bdkw1

10-1 is a pretty steep reduction. I would go for a 15T rear sprocket set-up.

McMaster Carr has bushing lock drive sprockets for a 7/8 shaft and 15T sprockets.

Do you know where to get a splined gear or whats the best way to keep the sproket from spinning. You will have to excuse my stupid questions cause im a horse trainer not a mechanic. I just trying to make a fun toy!

[Gene]

The end of the long shaft is splined and if you could find a sprocket to fit that might be a start. The shaft would need bearings on either side of the sprocket.

[fx4stroker]

Originally Posted by Gene

The end of the long shaft is splined and if you could find a sprocket to fit that might be a start. The shaft would need bearings on either side of the sprocket.

Yeah its a 15 spline shaft. Could you explain alittle more about needing bearings on either side of the shaft. Do you mean like a carrier bearing to help hold the shaft from moving forwards or back. Ive been gussesting the frame everywhere trying to make it stronger to hold more power but i didnt think about the diff moving.

[fx4stroker]

anybody else have a input on sprocket size?

[Gene]

Yes. A pillow block on either side to prevent movement.

[fx4stroker]

Does anyone else have any input on sproket size. If I go with a 15 tootch rear sproket that would me a 1:1 ratio for my sprockets.

[Gene]

My CBR had a 17 countershaft and 20 FNR.

The question is how is the thing currently geared. One-to-one might be right.