gy6 belt shreding

[yzguyfl]

’ve been having issues shredding the drive belt on my GY6 150 Kart. I just replaced the clutch, variator and belt, and I still think something is getting too hot, I only ran it for a few min and the side cover seemed very hot to me. I have 2 questions
Do any of these temps look too high? (I’m guessing the shredding is from the belt getting to hot)
Any ideas on what else might be causing the belt failures?

[Dallastx]

Not sure on the temps but if you've replaced those items it would seem that maybe a bearing could be causing a heat issue. If its going out causing more friction it would def get things up. Hope you find an answer soon.

[yzguyfl]

which bearing, where?
in the motor? on the crank? or something in the rear off the clutch?

[Dallastx]

My cvt used to heat up and smoke when I would ride it either hard or heavily loaded passenger wise prior to installing the sliders and 1500 spring. I never shredded a belt though. It would just smoke out the snorkels on the cover and I could feel and smell the heat. When I took the cover off the small bearing that connects the clutch shaft to the cvt cover would sometimes be "seized" onto the clutch shaft and some times be stuck on the cvt cover. After swapping out the sliders and main spring the cvt no longer struggled and climber steep hills without hesitation. I took the buggy to mena Arkansas for a four day trip on the 4th of July and was amazed at its climbing ability. However last weekend I started having issues climbing the smallest of hills and smoking out the cvt cover again though. I posted on here for help but it seems no one may have had my issue yet. I'm going to check the bearings and gears on my clutch shaft later on today. I'm in north texas and my second life is my kids select soccer so we have tournaments all summer long. As far as your heat issue I would recommend the bearings on the clutch shaft, cover and go from there I'm no expert by any means. Just trying to help out.

[Gawald]

By all means check your bearings, but I suspect they are not the source of the heat. Ball bearings usually fail by getting noisy and increasing internal clearance. Sometimes retainers fail too. Usually the cause is lubrication failure or contamination. I would look at belt slippage as a likely source of high heat as this can generate high heat from friction. Did you go to a Kevlar belt instead of using a rubber one? Has anything changed that could lead to belt slippage?

[ckau]

excessive heat leads up premature belt failure. 3 factors that cause heat.
Incorrect/cheap belts.
Pulley misalignment.
Driving style.
Most stock variators use the 743-20-30. A 115m variator likes THE 835-20-30 belt. We prefer Gates belts. They've shown to be good dependable performers. You can buy cheaper but you get what you pay for.
Kevlar belts can take excessive heat but there's a trade off with premature pulley wear. The Kevlar's are extremely strong and aren't prone to shredding but the nature of the belt wears ridges in the pulley faces. plus it's the general consensus of thinking should there be CVT failure it's best to bust a belt to serve as a indicator rather than continuing on until a more costly part is destroyed.
When a belt shreds, there's pieces of cord and bits of belt wrapped and lodged in the pulleys and shafts. It's important to completely disassemble the variator and clutch sections.Totaly clean out all traces. Failure to clean causes Misalignment and restricted movement which in turn leads to more heat... the continuing cycle of belt loss.
Driver style meaning a lot of folks think they can or should simply try to power over obstacles. If you're on the gas and the buggy doesn't roll forwards, the rpms climb but the buggy doesn't move, you've just smoked the belt and clutch. It doesn't take but a few seconds of this to generate enough heat to damage the system. Trying to climb rocks or a steep incline from a stand still is the worse thing you can do. either give enough room to get momentum and a little speed going or pick a alternate path. You can't allow the CVT to stall out!
If you already have these 3 items covered then there's a few tricks to help keep temps down. Remove the inlet rubber snout and take out the filter screen. this screen gets blocked and restricts air from entering the case. Running a piece of hose connected to the inlet snout routed up high keeps trash out. A section of hose from a wet-vac works good. some sort of filter on the end of the hose doesn't hurt.
At the rear of the case you'll see the exit port is very small and has a casting section designed to keep trash from entering the port. This port is very restrictive. Opening up this port allows more air flow to improve circulation.
Score a CVT cover from a howet motor. the case has a removable cover plate over the clutch. Replace the plate with a screen and filter. This gives a good cool air source for the clutch.
Polishing the pulley surfaces to a mirror finish improves belt grip and reduces fiction = less slipping, heat build up and wear.

[yzguyfl]

Originally Posted by Dallastx

My cvt used to heat up and smoke when I would ride it either hard or heavily loaded passenger wise prior to installing the sliders and 1500 spring. I never shredded a belt though. It would just smoke out the snorkels on the cover and I could feel and smell the heat. When I took the cover off the small bearing that connects the clutch shaft to the cvt cover would sometimes be "seized" onto the clutch shaft and some times be stuck on the cvt cover. After swapping out the sliders and main spring the cvt no longer struggled and climber steep hills without hesitation. I took the buggy to mena Arkansas for a four day trip on the 4th of July and was amazed at its climbing ability. However last weekend I started having issues climbing the smallest of hills and smoking out the cvt cover again though. I posted on here for help but it seems no one may have had my issue yet. I'm going to check the bearings and gears on my clutch shaft later on today. I'm in north texas and my second life is my kids select soccer so we have tournaments all summer long. As far as your heat issue I would recommend the bearings on the clutch shaft, cover and go from there I'm no expert by any means. Just trying to help out.

If you mean the needle bearings between the clutch assembly and the shaft it slides over, those are new, with the clutch assembly I just put on there.

Originally Posted by Gawald

By all means check your bearings, but I suspect they are not the source of the heat. Ball bearings usually fail by getting noisy and increasing internal clearance. Sometimes retainers fail too. Usually the cause is lubrication failure or contamination. I would look at belt slippage as a likely source of high heat as this can generate high heat from friction. Did you go to a Kevlar belt instead of using a rubber one? Has anything changed that could lead to belt slippage?

I’ve tried both normal and Kevlar belts, with the same results. When I first got the kart (used) it went for probably a few hours of riding before the first belt gave out. While I pulled the cover off, I also swapped out some clutch springs, and put in lighter weights to try to give it more low end torque. Since the first belt was shredded, I was guessing what the right belt was (no way to read the old one). Then this started happening after about 20 min of riding. So I went back to all new/stock variator (whole thing new with new stock weights) and clutch, new assembly with stock springs, and new bearings, ran for about 10 min and the cover is VERY hot. I’m not even 100% sure this is a heat issue, but strongly suspect it.

Originally Posted by ckau

excessive heat leads up premature belt failure. 3 factors that cause heat.
Incorrect/cheap belts.
Pulley misalignment.
Driving style.
Most stock variators use the 743-20-30. A 115m variator likes THE 835-20-30 belt. We prefer Gates belts. They've shown to be good dependable performers. You can buy cheaper but you get what you pay for.
Kevlar belts can take excessive heat but there's a trade off with premature pulley wear. The Kevlar's are extremely strong and aren't prone to shredding but the nature of the belt wears ridges in the pulley faces. plus it's the general consensus of thinking should there be CVT failure it's best to bust a belt to serve as a indicator rather than continuing on until a more costly part is destroyed.
When a belt shreds, there's pieces of cord and bits of belt wrapped and lodged in the pulleys and shafts. It's important to completely disassemble the variator and clutch sections.Totaly clean out all traces. Failure to clean causes Misalignment and restricted movement which in turn leads to more heat... the continuing cycle of belt loss.
Driver style meaning a lot of folks think they can or should simply try to power over obstacles. If you're on the gas and the buggy doesn't roll forwards, the rpms climb but the buggy doesn't move, you've just smoked the belt and clutch. It doesn't take but a few seconds of this to generate enough heat to damage the system. Trying to climb rocks or a steep incline from a stand still is the worse thing you can do. either give enough room to get momentum and a little speed going or pick a alternate path. You can't allow the CVT to stall out!
If you already have these 3 items covered then there's a few tricks to help keep temps down. Remove the inlet rubber snout and take out the filter screen. this screen gets blocked and restricts air from entering the case. Running a piece of hose connected to the inlet snout routed up high keeps trash out. A section of hose from a wet-vac works good. some sort of filter on the end of the hose doesn't hurt.
At the rear of the case you'll see the exit port is very small and has a casting section designed to keep trash from entering the port. This port is very restrictive. Opening up this port allows more air flow to improve circulation.
Score a CVT cover from a howet motor. the case has a removable cover plate over the clutch. Replace the plate with a screen and filter. This gives a good cool air source for the clutch.
Polishing the pulley surfaces to a mirror finish improves belt grip and reduces fiction = less slipping, heat build up and wear.

So far the type of belt used has not made a bit of difference, although maybe someone can fill me in on what makes a good or a cheap belt? (other than price, someone can also put a high price on a cheap belt….) I did try 1-2 Kevlar belts (I don’t remember how many) and they shredded the same.
I will check pully alignment, had not thought of that, although not sure how that could have happened.
I live in FL, and mostly drive around the yard (5 acres), no hills here 
I was thinking of getting a spare cover for so I could cut it up and maybe add vents or something, or removable sections so I could see what was going on in there while it was running, like if the front was hotter than the back.