Best go kart tire&wheel setup for me.

[Singularity]

Hey guys! My first post here at DIY. I need help deciding on my wheel and tire setup. I am taking the Carter Bro's Turbo Tiger frame in the link bellow.

http://ec1.images-amazon.com/images/I/41uiGavKWCL._AA280_.jpg

It was the kart I rode when I was a kid, I am 15 now. My dad sold it to a friend so his kids could enjoy it after I got my first quad. Now they have outgrown it so I decided it would be fun to rebuild it this summer and beef it up a little.

I am moving the steering to the middle, putting a bucket seat in and under the hood, or in the back rather I am going to toss in a Briggs 9 HP engine, a TC2 CVT #1004 torque converter. I am sure I am happy with this setup so don't comment on that. What I am wanting to do is to get some big 10-20 inch tires on it to hopefully make the ride a bit smoother. It will be for light off roading. So nobby/ turf tires maybe. Skinnier in the front, pretty wide in the back.

WHAT I NEED TO KNOW IS:

What are the best tires and wheels for my purposes. What sizes to get, and maybe a nice established supplier to buy them from. With the tire size you recomend give a gear ratio you would recomend and why. I am thinking it can be relatively fast ratio considering engine size.

All help is apretiated, thanks!

 

[redsox985]

and under the hood, or in the back rather I am going to toss in a Briggs 9 HP engine, a TC2 CVT #1004 torque converter. I am sure I am happy with this setup so don't comment on that.

I'm commenting anyways. Don't be so set on this. The Chinese clone torque converters lie about their capability. The originals that are better quality can't take more than 8HP. You may be able to get it to work with the right gearing, but a more costly 40 series Comet torque converter will be your bet that's guaranteed to work, this one is a long shot. You say you want speed? You aren't going to have the speed you want if you gear accordingly to satisfy that TC.

 

[Singularity]

Ahh, I you speak the truth! Comets seem to be hard to find- is it true they went out of buisness? I still want a TC I think, the prospect of a automatic transmission capable of 40% underdrive, 20% over drive an everything in between is quite attractive. I agree I should look into a better a better quality TC, but as far as speed goes I could put a 5:1 or 6:1 ratio on my final drive and that means with a TC anywhere from a low 7:1 ratio in underdrive to a 4:1 in underdrive. With 10" tires that is about 35 mph, and I bet a nine horse engine can handle that; especially considering I can go 26 mph on my bike when a human can produce at most 3 hp- on a standard bike. Is my logic sound? Now that I am working on my engine what do you think about the rest of the project, specifically wheel size? How big can I go without robbing power by having too much weight to turn or other issues? For the tires you recommend, what is the most convenient way to get hands on them? I want to do better than the dinky wheels it came with.

 

[redsox985]

Well, when compounding gear ratios, they're multiplied, not added. A Comet 40 series was a low of 2.5:1 and a high of 1.15:1. So if you had 10 teeth on the jack shaft (JS) and then 50 on the axle, you would have low of about 12.5:1 from a stand still and a high of slightly over 5:1 at top speed. With 9HP and a Comet 40 series, you can use up to about 20-22" tires, although I wouldn't go over 18-20" IMO. What kind of speed do you want?

On my kart, I have a CAT99 TC, the precursor to the 30 series, and my low ratio is about 13:1 and my high is 5.4:1 with 18" golf cart tires and tops out around 35 MPH, with a 6.5 HP stock clone engine.

 

[Doc Sprocket]

Redsox, where did you the 40 specs- all the data I have states a 1:1 high ratio for the 40 components, not 1.15:1. Has something changed?

 

[redsox985]

http://www.gokartsupply.com/4044seri.htm

If you scroll down to speed reduction ratios, it has them listed. I kinda estimated between the two ratios. They're with the 44 Mag. driver and 44 or 40 driven. It's 1:1 with the 40 driven, 1:1.25 with the 44 driven. I don't know how available either of these are, so I took a middle ground assuming that it would split the difference as I don't think we would pass up the opportunity to buy Comet regard less of whether it's a 40 or 44 series.

www.gokartsupply.com now has clone 40 series TC's in stock.

 

[Doc Sprocket]

Ahh-I understand. I was referencing my Comet 40 manual and saw the two ratios (40 and 44) but it didn't occur to me you averaged them. Gotcha.

 

[redsox985]

Sorry, I should have noted that. I believe that CVTech makes CVTs for 1" bore. They're used by many SAE mini-baja teams on the 10HP Briggs engines they use. I don't see why it won't work with 9HP. We have no experience with the Chinese copies, but if engineering students will bash on these for 4 hours and trust them year after year in their buggies, they're probably top notch.

 

[Singularity]

Wow- so the TC really does increase low end torque. Thanks for fixing my gear ratio math, gotta think about my physics! Those comet clones were the ones I was looking at, are they still low quality?? I want a decent top end 30 mph or so at 3600 rpm. More importantly perhaps is acceleration, the ability to spin the tires and rocket off the line. Now I know spinning the tires doesn't make you go faster and that TCs act a little like traction control. Now anyways, I was thinking about doing some math to take the tire size into account and create a "true" ratio of sorts to help me find gear ratio and tire size best for me. I know a lot of people call 6 the perfect ratio but never mention tire size. Now gear ratios seem to be more limited than wheel size. I've messed with online speed calculators and experimenting with what gears/ tires I could go to make the most out of a top speed of 30 mph- my real issue I guess is I don't know a top speed for 9 hp swell as various specific advantages I would get with one wheel and tire type or another. So should I go with those big golf kart tires or mini quad wheels or dinky lawn tires. This is what I need to know.

 

[Singularity]

Just for clarification; the comet clones I have been looking at, the same that you recommended, are rated up to 13 hp by the sale page claims. They still call them Comet 218355a TAV2 30-100. The part I'm worried about is that 30, they are still comet 40 clones, correct?