Looking for a little help with super mod

[Mike Kieffer]

  I have started on a super mod for the upcoming season and it is coming along well. I have a few questions on pulley sizes that I should start out with. I am running a 44 ci. vertical shaft engine with a centrifugal clutch to a right hand gear box. I know they weld pulleys to the clutch so getting as close to the right size as you can is really important. Any help you can give me would be greatly appreciated.


Mike

[2nstoys]

I set my clutch up with a 4 inch and then I have a 7 and 8 for the rear. Gives me a range of 6 thru 8 to 1 with the normal size sprockets in back. 13-15 drive and 46 - 52 driven sprockets. Hope that helps.

[George Herrin]

Be sure to use a pulleys less belt slipage equals less heat equals longer belt life.

[Tom Price]

Be sure to use a pulleys less belt slipage equals less heat equals longer belt life.

You mean A section belt pulleys instead of A/B pulleys George?


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[George Herrin]

yes

I would not use anything less than a 4.5 on motor. I prefer 5" more belt wrap but my last was a 4.5 works well
4.5 to 8 to 12 to 52 is 7.7to1 final ratio using a 40 on axle changing nothing else gets you down to 5.93 so you have a wide range of adjustment there.

[Tom Price]

yes

I would not use anything less than a 4.5 on motor. I prefer 5" more belt wrap but my last was a 4.5 works well
4.5 to 8 to 12 to 52 is 7.7to1 final ratio using a 40 on axle changing nothing else gets you down to 5.93 so you have a wide range of adjustment there.

Cool, never thought about using A section pulleys instead of A/B


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[George Herrin]

gives a more accuurate measurement better belt grip and your using a clutch (NOT mechanical) so you dont need the extra depth to keep the belts on

[Mike Kieffer]

Thanks to everyone that gave me some input.I agree with you George on the A pulleys but I thought that they were getting hard to find. I hope I don't sound stupid but what do you mean when you say section pulley.what can I do to get myself to a 14 or 15 tooth gear on the gear box or is this not a good Idea.

[Tom Price]

An "A" section belt is 1/2" wide, a "B" section belt is a 5/8" belt.  Most pulley now are A/B section belt pulleys but you can still find A section pulleys


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[Rooster]

The difference between sizes in Pulleys is the "Section size"...basically cut one and look at the end.
You are looking at the "cross section" of the belt.  That is how they are classified, which is why many people refer to them as "A Section" or "B Section" belts and pulleys.

a GOOD READ...
http://www.gizmology.net/pulleysbelts.htm

The problem with A/B Pulleys is they are made to fit either belt, not a specific size, so they fit neither correctly!

[2nstoys]

I do run the a-b pulleys but I run 5/8 belts. I have no belt slippage yet. And have been on some very sticky tracks.

[Mike Kieffer]

I knew the difference between the belts I just have not heard them referred to that way, and I didn't know if there was something I was missing. You learn something new everyday!
  OK so I think with the input that I've been getting I have an Idea of where to start. I would like to get to between 40 and 48 teeth on the rear axle because I have two sets of all of them and it would save a little cash. It sound like I my need to buy a few more sets up into the 50s to get where I need to be.
 I have not got a good grasp on the hole gear ratio thing and how to apply it to the real world. I just know what to do if I need more or less Rs at the end of the strait away.

[George Herrin]

I would start at 6.5 to 1 and see how the motor likes it. Everything acts different with real race tires that grip...

[Mike Kieffer]

I will George Thank you

[Eatondirt]

I assume that were taking about using the 15 inch by 8 inch tires?  As far as gear ratios are conserned