is it possible to burn up a torque converter?

miniblazinbmx

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Im experiencing a power plateau on my last couple of test rides, what feels like before my kart was kicking and pulling hard now feels like its got less than its balls at the same throttle and speeds. besides a couple of rough test runs with really high gearing, nothing has changed, I was going to rip it apart this week anyway for lower gearing, but now I have concerns we should look at replacing other parts. So aside from some springs and weights, is there anything else in the clutch system I should look to for any issues? Its a 18hp duromax running stage 1 with governor. currently running 17/54 because thats what we had but I have a 10 and 12t here finally to try out. Were running a china 40 series with upgraded springs. before this thing has hit 50+ no issue now it struggles it feels like past 35mph..
 

FlyFrog

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make sure your belt isnt slipping, if it is tension it if you can if not buy a commet belt, dont buy anything cheap, it will just tear up into pieces from what i heard
 

Denny

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If you are running a rear tire taller than about 10” your gear ratio will burn up the belt even a quality one fairly quickly. We need more information about your setup.
 

miniblazinbmx

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duromax 440cc stage 1 (governed)
40 series TC(red springs)
comet belt
18" tires
54t axle
17t clutch/driver(current as stated before others arrived), 10 and 12t now ready for swap

I dont see damage on the belt really but I figured maybe that might have be the issue too. Its very possible we stretched and ruined our belt with this setup then..? thoughts on a new belt and maybe 12/54?
or is 10/54 really the best midrange gearing for a YerfDog restomod, hotrodded and modified?
 

madprofessor

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is 10/54 really the best midrange gearing for a YerfDog restomod, hotrodded and modified?
Higher ratio there at 5.4:1, would have much greater acceleration than that 3.2:1 ratio, but may wind out before the top end you want. Yet and still, personally I'd have a higher ratio than even that. I like doing doughnuts.
maybe 12/54?
That 4.5:1 ratio would have decent acceleration, and more of the top end you want. Thing is that most would run the higher ratio with the 18" tires because of burning belts.
 

Denny

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The high horse power is going to hurt the belt the most if you just floor it from a standing start. If you are riding off road and doing that a lot then go with the 10 tooth sprocket. If you are slow into the loud pedal or ride on hard surfaces I would stick with the 10 tooth still for reliability. The penalty is a lower top speed. If you really need the extra speed then go with the 12 tooth.
 

miniblazinbmx

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The high horse power is going to hurt the belt the most if you just floor it from a standing start. If you are riding off road and doing that a lot then go with the 10 tooth sprocket. If you are slow into the loud pedal or ride on hard surfaces I would stick with the 10 tooth still for reliability. The penalty is a lower top speed. If you really need the extra speed then go with the 12 tooth.


I have plans to modify this kart further to make it handle better, however, its come up on two wheels pretty easily with my son on it and I don't necessarily need to do 60mph in this kart. 40-45 is plenty. I don't mind losing some top end for now. it only spins to 3600 with the governor anyway. I guess with the higher HP there is also higher torque but I would rather use it on the low to mid range end.
 

Denny

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I don’t know what your kart looks like. But if it were mine I would try the 12 first then a 10 tooth. It worries me to hear that it pulls the front wheels with your son on it. Maybe this is not the kart for him? How old is he, it might be better to start him off with a smaller engine.
 

miniblazinbmx

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I don’t know what your kart looks like. But if it were mine I would try the 12 first then a 10 tooth. It worries me to hear that it pulls the front wheels with your son on it. Maybe this is not the kart for him? How old is he, it might be better to start him off with a smaller engine.
I havent updated my thread much lately but we have the Kop Kart. the police theme yerf dog 3002. This kart is ours, its a bit much for him for sure, but we have two more we are building and one has twice the stopping power and half the ponies, and will be further metered down so he can learn to drive on that one.
Another reason I was asking about gearing, so i would have a better understanding going forward on the other builds. I will try a 12 as you suggest because thats what makes sense to me too.
 

Willie1

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I don’t know what your kart looks like. But if it were mine I would try the 12 first then a 10 tooth. It worries me to hear that it pulls the front wheels with your son on it. Maybe this is not the kart for him? How old is he, it might be better to start him off with a smaller engine.
I'm not sure which two wheels he was referring to. Since he was talking about handling and top speed, I thought he was referring to being on 2 side wheels in a corner, not the 2 rears in a wheelie. But in either case 18-20hp is a lot of power for a "learner" kart, without some sort of a throttle stop.

I haven't seen anyone mention if the converter is "shifting" or not. You may not lose much - if any - top end if the 3.2:1 ratio isn't letting the driven pulley work it's magic. Getting the revs up - on both drive and driven pulleys - may let the converter work in a happier place.

I've gotten a little extra life out of "seasoned" belts by soaking a scotchbrite pad in acetone and scrubbing the v sides of the belt and the pulleys and blowing them off with air.
 

miniblazinbmx

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I'm not sure which two wheels he was referring to. Since he was talking about handling and top speed, I thought he was referring to being on 2 side wheels in a corner, not the 2 rears in a wheelie. But in either case 18-20hp is a lot of power for a "learner" kart, without some sort of a throttle stop.

I haven't seen anyone mention if the converter is "shifting" or not. You may not lose much - if any - top end if the 3.2:1 ratio isn't letting the driven pulley work it's magic. Getting the revs up - on both drive and driven pulleys - may let the converter work in a happier place.

I've gotten a little extra life out of "seasoned" belts by soaking a scotchbrite pad in acetone and scrubbing the v sides of the belt and the pulleys and blowing them off with air.
2 wheels on the side correct. and this is not a learner kart, that is the other build.. but the top end was insane on this before. after regearing we are at 40mph top speed with the governor still. its a lot more manageable. will be trying a diff setup on the next for sure.
 

Willie1

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2 wheels on the side correct. and this is not a learner kart, that is the other build.. but the top end was insane on this before. after regearing we are at 40mph top speed with the governor still. its a lot more manageable. will be trying a diff setup on the next for sure.
Only mentioned the "learner kart" because you mentioned you were building a tamer kart for him to learn on, and the Duromax was a bit much for him. At that point I was just agreeing that a 20 hp Kart with a knack for tire levitation might not be the best one to hang the "student driver" sign on LOL. I wasn't trying to insult anyones abilities - at 20 hp most karts are a handful that you need to respect and feel comfortable in, or comfortable putting someone else in.
 

madprofessor

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Personally I love doing wheelies, seeing the clouds for once since my neck won't tilt back far enough anymore to do otherwise. Only brought up the sissy wheels in consideration of little kids who might get their hands on a naturally levitating machine. They need steady steering capability.
 

madprofessor

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Wheelie bars do nothing for steering. At all!
???????? Not sure of the point there, but one point taken.............Wheelie bars keeping the front end from popping up more than a few inches indeed do not aid steering while the front end's a few inches up in the air, complete agreement there. I'm only thinking about the length of time between leaving the ground and coming back down.
I've got a lot of 2-wheeler experience where huge power would levitate the front wheel at the most inopportune of moments, like when sideways in a powerslide corner. Even a second of that can result in all wheels being off the ground, as in upside-down off in the trees. Hence my thought that the less time of no steering, the better for the kids.
 
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