Clutch and Tire question

[Raviolikid134]

Well I have a Hillard Extreme Duty rated for 13hp. I also have 18x9.50x8 tires. On my first run today I noticed allot of smoke coming off the clutch so i immediately stopped and realized i forgot to oil the clutch and chain so their was less than 2 min of use "dry". I lubed the chain and clutch and smoke was still coming off the clutch, at first i figured it was just some paint heating up but after about 3 more min of drive time it never did stop. I killed it and pulled over. Fairly sure my tires are the problem, I need smaller tires. Not to mention I had no tq, I have a gx200 with a few odds and ends done to it and a 12t clutch and 70t sprocket, so it should be peppy at least. So would a new set of back tires fix this problem?

 

[Rickracer]

Check it out: http://www.gokartracing.org/Calculate.htm
Based on your "calculated" tire circumference, you've got a 5.83:1 gear now, I think for that size tire, you're gonna need in the neighborhood of a 6.5:1 to 7:1.

 

[Raviolikid134]

Hmm I must have done the math wrong first time I calculated it. Still doesn't solve the smoking clutch though. From what I read I can run 16x6.50x8 or 16x7.50x8s on my rims. Would that fix my clutch problem?

 

[Rickracer]

You gotta figure, they run as high as 70 tooth sprockets on race karts with 38 diameter tires, even a 16" tire is gonna be over 50" in diameter. I ran 15 x 63 in my race kart with about a 12 hp Honda motor on it, and that was good for about 60 mph. My kart only weighed 303 lbs, with me on it.

 

[Kaptain Krunch]

Your gear ratio seems fine to me, how big is your kart? With that ratio, 18" tires, and a governed engine your top speed should be about 33mph which is not much to ask. Does your kart roll freely? is your chain tight? are your bearings stuck? is your engine reaching redline? it may not be fully revving up and never fully engaging the clutch.

 

[Raviolikid134]

My carts about 7-8 ft long, bout 3 feet wide at the widest point. The governors been removed, chains tight, bearings are good theyre brand new, im not giving it enough gas to hit redline(bout half throttle). Theirs 1800rpm springs in it right now. Itll roll freely but itll stop soon after but I account that with the extra weight. I need to weight it.

 

[Kaptain Krunch]

the chain shouldn't be tight, should be 1/2" to 3/4" up and down slop in chain.

 

[theo]

I think you need a CVT with those size tires.

 

[anderkart]

I lubed the chain and clutch and smoke was still coming off the clutch

Were you riding in a small area, maybe doing allot of stop and go or slow riding where the clutch had to constantly slip the whole time?

If so, centrifugal clutches can handle being in "slip-mode" like this for a short time, but they just keep getting hotter and hotter from all that friction. Once you get up to the speed required to fully lock the clutch in, it has no friction and can finally cool down. Torque converters work beter for this kinda riding because they start out in a much higher ratio so they're clutch doesn't have to slip so much. Taller rear tires make this problem worse.

 

[Raviolikid134]

I think you need a CVT with those size tires.

Id much rather go with smaller tires than have to get a CVT setup.

Were you riding in a small area, maybe doing allot of stop and go or slow riding where the clutch had to constantly slip the whole time?

I was riding in my yard, its a decent size but i was on and off it when i was riding just cuz it kept smoking and i didnt want to already burn up the clutch.

Should i just get new tires or try and run it tomorrow at WOT?

 

[modelengineer]

It's better for the clutch to run WOT and get up to speed as quickly as possible. The more time spent tootling around with it slipping, the quicker it will wear out.

 

[anderkart]

If most of your riding is going to be low speed, stop and go riding, you need to do whatever you can to not allow the clutch too be constantly slipping. (again, you can let it slip for short while but not constantly)

This might be using shorter tires, instaling higher ratio gears (maybe a jack-shaft setup if necessary) or just driving fast enough to get the clutch past the point of slippage and fully locked in.

If you were just trying your kart out at home and you'll mainly be out riding it somewhere else at higher speeds, you may not have to change anything.

 

[Raviolikid134]

I have a extra set of trailer rims laying around. Theyre 16"s tall, I know they'll fit on my hubs. This might help the problem a little bit. Im going to try that today and take it down my road and just give it hell and see what happens.

 

[freakboy]

trailer rims are heavy as hell man that wont do much good.

 

[Raviolikid134]

trailer rims are heavy as hell man that wont do much good.

Im going to compare my old rims to the trailer rims first. If it comes down to ill just bite the bullet and buy some 6x4s or 6x3s or what ever size they are

 

[anderkart]

Sounds like you don't want regular/short kart tires. There's quite a few 16" tall tires available (4.80X8.00-8 or 16 x 6.50 - 8) that would probably fit your current 8" tall rims and help your gearing out a bit:
http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4DMUS_enUS221US222&q=8"+go+kart+tires

How wide are your rear rims?

 

[Raviolikid134]

My rims are 7" wide. I dont mind the short tires its just I like the mean stance that the bigger tires give. Plus im going to be driving around on the street and my yard so I dont want just straight up slicks.

 

[anderkart]

So yeah those tires I mentioned should work fine on your old rims. But If you buy some new 4", 5" or 6" (tall) rims, going with standard sized go kart tires around 10" 11" or 12 tall would help your clutch issue out even more. (you'd also get better acceleration but a lower top speed)

They're not all slicks, you can get these sizes with tread: http://www.google.com/search?source...rlz=1T4DMUS_enUS221US222&q=go+kart+tires+rims

 

[Raviolikid134]

Well today i loosened up the chain, properly lubricated the chain and the clutch and put trailer rims on it just for ****s and giggles, they were 4.80x8. No smoke or anything I have my torque back thats for sure. at 3/4 throttle i was hittin 35 and i was still gaining speed but then i ran out of road. I need to redo my brake setup but other than that the things doin great. Scares the ever livin crap outta me lol. Thanks to all the advice you guys gave me.

 

[anderkart]

Cool, are those trailer tires around 16" tall?