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Old 03-25-2019, 03:26 PM
pxmartin pxmartin is offline
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Rebuilt an old Yerf dog go kart for the grandkids. It has a new 212 Predator motor, torque converter that has 12 teeth and 35 chain. It has 20 inch rear tires on it. With my daughter test driving it, 125 pounds, it slowly rolls and increases speed ok. but when you slow to turn around it comes to almost a complete stop. I think it has a 60 tooth sprocket on live axle. The kart is not here so I can't check it. It has 16 inch tires on the front. Should I change the rear tires to 16 inch also?

TIA
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Old 03-25-2019, 03:32 PM
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Do you know what the stock tire sizes were?
Also, we're too lazy to bother trying to picture what you're saying.
So... please post pics!
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Old 03-25-2019, 04:13 PM
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Yes, these are the stock tires on the kart. Not lazy, as stated in original message, The kart is not Here at my house. It is 3.5 hours away from me.so I cannot post any pics.
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Old 03-25-2019, 04:22 PM
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Quote:
Originally Posted by pxmartin View Post
Yes, these are the stock tires on the kart. Not lazy, as stated in original message, The kart is not Here at my house. It is 3.5 hours away from me.so I cannot post any pics.
What do you mean by it almost comes to a complete stop when you try to turn.

I'm not sure if you are saying there is a problem with the brakes or the steering.

1: I'd need to know if its band or disc brakes to go further with brakes.

2: A live axle kart is always going to have slightly wonky steering. You have to give it gas through a turn or be going at least a few mph. Unlike a one wheel peel or a differential kart, it takes some decent force to get a live axle kart going through a turn. Check your front and rear tire pressure. If the steering is getting bad, as it doesn't respond well, inflate the rear tires and deflate the front tires.
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Old 03-25-2019, 04:47 PM
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Thanks. Going to visit the grandkids next week. Will have the kart to look at and post some picks. Yes the daughter was probably not giving it enough throttle when she turns. She said it is extremely slow when starting from a stop, Sometimes she has her husband push some to help get it going. (The grandkids are to small to reach the pedals so that why the daughter has to drive)
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Old 03-25-2019, 08:00 PM
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Replace the centrifugal clutch with a CVT. The centrifugal clutch is slipping it's but off, not a good situation. A Chinese 30 series CVT should fix it right up (and make the kart more fun also).
They can be found on E-bay and other places for under $75.00. A 10 tooth primary sprocket and a 60 tooth axle (#40 chain) will fix it up quite nicely.

Denny
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Old 03-25-2019, 08:07 PM
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Also make sure the cable is pulling full way and the throttle limiter screw is pulled out full. You need that clutch spinning as fast as possible to get the wheels turning.
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Old 03-25-2019, 08:13 PM
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I started with a centrifugal clutch and it slipped big time. So I installed a torque converter and it performs a little better. That is what is on it now.
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Old 03-25-2019, 08:25 PM
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Quote:
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I started with a centrifugal clutch and it slipped big time. So I installed a torque converter and it performs a little better. That is what is on it now.
So 16" tires, 6:1 ratio, 6.5HP, and a 125lb rider...and it doesnt move? My Dingo has 18" tires, a heavier rider and otherwise same specs and if I even dare to touch the throttle my *** gets whipped back like a bat out of ****. Even a centrifugal clutch given those specs should move pretty nicely.

Check your belt to ensure it is the proper belt. Also make sure there is no oil on the torque converter sheaves because that can make you lose all belt tension. Also see if the brakes are jammed at all.
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Old 03-25-2019, 08:48 PM
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Yes 16 inch tires on the front and 20 inch tires on the rear
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Old 03-25-2019, 08:56 PM
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Check and make sure the throttle is opening all the way with the gas pedal.

Denny
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Old 03-25-2019, 09:33 PM
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Yes 16 inch tires on the front and 20 inch tires on the rear
Oh they're 20". Well thats a problem....a bit of one. I don't think 20" tires should be a huge deal given I have 18's with similar specs so I don't imagine 20" being a huge deal. Given the brakes aren't jammed up, somehow the torque converter isn't transferring power, since that is the only "slippable" transfer of power between the engine crank and the wheels. Pull the belt with your hand(with the motor off of course) and see if the kart will move. If it will, check to see why the driver won't grab the belt. If its the driven, see why the driven is slipping on the belt. All belt surfaces should be shiny(at least decently reflective), smooth, and free of oil and water. Use brake clean if necessary, then wipe down. Make sure no brake clean gets on the belt.
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Old 03-26-2019, 12:03 AM
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From what you have said, it is a gearing issue, and nothing else (ok, maybe check that the throttle pulls butterfly open all the way at WOT).

With 20" tyres, you are going to need a lot better ratio than 5:1. That is just waaaay too high for what you have. The 30 series is not going to compensate for that. So.....what you can either do is try 16" tyres on the back. This will help a bit.....or you can get a smaller TC sprocket or bigger axle sprocket. Ideally for your situation you want at least a 7:1 ratio.

That is my 2c worth
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Old 03-26-2019, 10:12 AM
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From what you have said, it is a gearing issue, and nothing else (ok, maybe check that the throttle pulls butterfly open all the way at WOT).

With 20" tyres, you are going to need a lot better ratio than 5:1. That is just waaaay too high for what you have. The 30 series is not going to compensate for that. So.....what you can either do is try 16" tyres on the back. This will help a bit.....or you can get a smaller TC sprocket or bigger axle sprocket. Ideally for your situation you want at least a 7:1 ratio.

That is my 2c worth
Yeah 5:1 is really tall but for probably below 250lbs total weight, it should atleast be able to start by itself ok...not be fast and it will slip bad but it should run by itself with a T/C. Now if it was a clutch, yeah that thing would smoke for days.
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Old 03-26-2019, 10:46 AM
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I ran 22" tires on my cart with a torque converter. 8 tooth on the driven 60 tooth on the axle. 7.5:1
It worked fine with that set up.. i would not go any less with the gearing tho.
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Old 03-26-2019, 03:14 PM
pxmartin pxmartin is offline
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I am going to put a 9 tooth T/C sprocket on it and give it a try. If still not acceptable I will replace the 60 tooth axle sprocket with a 72 tooth sprocket. Does the sound like a good plan of attack? Thanks for all the good advice.
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Old 03-26-2019, 04:09 PM
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Quote:
Originally Posted by pxmartin View Post
I am going to put a 9 tooth T/C sprocket on it and give it a try. If still not acceptable I will replace the 60 tooth axle sprocket with a 72 tooth sprocket. Does the sound like a good plan of attack? Thanks for all the good advice.
That will boost you from 5:1 -> 6.6:1, sounds good to me. Make sure the 72 will fit if the 6.6:1 still causes issues(which I doubt). 8:1 should be PLENTY. Also note you will most likely need to shrink the chain by a link or two so have a chain break and half links on standby incase you need them. Depending on how much movement your motor mount gives you and it's current position right now, you may or may not need to remove any links.
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