tire size and sprocket size

[hothead]

I am putting a 440 snowmobile engine on my BSR, and was wandering the best size tire and sprocket sizes to use? I am going to keep the original driven clutch setup on it.

[speeddemon0308]

you do NOT want to do that..

you WILL have to run it to a jacksahft and put a 2:1 reduction on it ( or what ever the chain case is on a sled ) or you will never top it out.. unless you plan to go 150MPH+

even a 3:1 reduction would be better.. i dont think you would want to go 100 mph on a barstool..


ive already tho0ught about all this.. acaully.. cheack thsi out!!

http://i41.photobucket.com/albums/e276/speeddemon0308/th_PIC_0010.jpg (http://i41.photobucket.com/albums/e276/speeddemon0308/PIC_0010.jpg)

[hothead]

would it be possible to put the driven clutch on the axle itself? I plan on taking it to the local dragstrip if they will let me run it. I would like to set it up to where I can change gearing for different riding conditions. Any ideas?

[hothead]

What size was the engine?

[speeddemon0308]

the one in the pic? i think its a 440RV engine..

uhmm .. you are stupid if you stick it directly on the axel.. and im not joking...

look at the chain case.. it is gear reduced to 2 rpm of the motor is 1 rpm of the cogs.. and you want to go 1:1 more less.. stupid!! you will hit close to 250 mph... no way...

send it threw a jackashft and gear it down to 2:1 and then let us know how fast it still is... dotn forget.. the clutchs are pretty well torque a verters.. so when take off your at like 14:1 threw just the clutchs... and then after you wind it out.. is like 0.9: 1 or so..


we talked to soem one who raced carts.. and when he ran the seld engines.. he said it was threw a jackshaft.. and he had to screw the tires to the rim.. and he raced on dirt!

[hothead]

Can you make any suggestions as far as jackshaft and axle gearing? Don't want to go 250, but 100 would be cool for the track and then change it to cruise around fairgrounds or the neighborhood. Thanks for your help. I don,t quite understand the gear reductions.

[hothead]

I just want to build something different. It doesn't have to be the fastest thing around just extremely fun!

[speeddemon0308]

well.. im assuming the driven cluthc is 1" with a 1/4" keyway...

just set that up to a 1" jackshaft with 1/4" key in it.. 2 bearings to suport it..

honestly im not exactly sure what to tell you to run for sprokets from the jackshaft to the rear axel.. if you went 20 tooth to a 40 tooth.. theres your 2:1 or you could even go with a 20T to a 50T and you have a 3:1 reduction.. and youd still have plenty of speed!!

[hothead]

I don't think it has a keyway, but I could take it to a machine shop and have them put a keyway in it. Thanks for the help!

[speeddemon0308]

it SHOULD.. if not its taperd.. and if the big end is 1" then just have it bored 1" all teh way then keyd.. i know most are either keys or splines tho...

what engine do you plan on using?

[hothead]

79 kawasaki 440. I think the clutch side is splined. Not sure about the chain side i am taking the chaincase apart this weekend

[speeddemon0308]

ok.. and what have you found?

[hothead]

I cut the sled jackshaft in half, but it was a solid 1 inch shaft. I was able to use the brake rotor from the sled. I will get a keyway machined into the jackshaft for a gear. I might be able to use a dirtbike sprocket on the jackshaft but I will have to check it first.

[hothead]

The chain side did have a keyway like 1 inch long for the brake rotor and the sprocket was splined and held on by a bolt

[speeddemon0308]

but it was a 1" shaft?

thats good!! easy to work with... thats what alot of sleds have.. has to be able to take the power from the motor without twisting in the center...

just take everything off... clean it up have a keyway machined the whole length and put 2 bearings on it.. and run the clutch to it.. ( make sure you mount it was the CORRECT length and make sure its square.. ) and then run the sproket to the rear end... im not really sure what to run for sprokets tho.. mabey hok up on a sled racing forum to see what they think?

[hothead]

Good idea thanks