CVT belt climbing

[david-ab]

Finished the break-in procedure on my non-hemi 212 Predator after changing the piston to a flat top one (changed the rings as well...), adding a loop pipe and an ARC Billet Rod.

My current setup is:
Governor removed
Aluminum fly wheel
Dover coil
22 lbs springs
Performance valve set
1:1 rockers
Nibbi pe24 carb
Flat top cam
6252 ARC Billet Rod
Ported intake and outlet
800mm length loop exhaust pipe
30 Series CVT

After installing the CVT I noticed that in half throttle the timing belt is climbing too high and getting stuck on the pulley (I added a video).
Before adding the new modifications (flat piston, loop pipe & billet rod), I measured 6900 rpm on the engine shaft.
Is it possible I am exceeding the rpm limit of my CTV? and if so what kind or clutch / CVT do you recommend? its for an offroad go kart.

Heavily modified 212 predator

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[Denny]

DON’T DO THAT!!! It’s extremely dangerous and stupid!!!!
For a CVT to properly function it must be under load.

 

[Hellion]

I had to watch the video to see what got Denny riled up.

An engine prefers to have a load on it too. There's way too many people that insist on putting an engine on the ground and revving the snot out of it. In that scenario you can free-rev it faster than it will ever go when it's properly connected to a sprocket, chain, wheels and/or a vehicle. Seen engines go kablooey doing that as well. Measure the shaft RPM when it's actually moving a kart, then report back.

Yes, it is very possible that you are exceeding the design limit.

Edit: Just don’t be that guy

 

[panchothedog]

The spring in the secondary ( driven ) clutch is weak, broken, or in the far right side hole. It probably won't do it under a load, but even what you were doing, it is closing much to quickly. Disassemble the driven and move the spring one hole to the left. Or replace altogether. Springs stronger than stock are available. Put the new spring in the center hole.

 

[david-ab]

DON’T DO THAT!!! It’s extremely dangerous and stupid!!!!
For a CVT to properly function it must be under load.

Relax buddy, the worst thing that could happen was a flying belt and I was wearing protective eye wear, not to mention I was giving it less then half throttle.

The spring in the secondary ( driven ) clutch is weak, broken, or in the far right side hole. It probably won't do it under a load, but even what you were doing, it is closing much to quickly. Disassemble the driven and move the spring one hole to the left. Or replace altogether. Springs stronger than stock are available. Put the new spring in the center hole.

Where can I find a stronger spring? I thought the red one is the strongest. Also I thought of getting the Juggernaut Super 30 Series Driver, just because it was tested for higher RPM....

 

[panchothedog]

OMB Warehouse. The juggernaut won't help your problem of the driven opening up too quickly. You can also purchase ( from them ) lighter weights and stiffer garter springs for the driver. Much cheaper than the juggernaut and with different springs you can tune it to your liking. I have a juggernaut on one of my karts, and honestly the spring and weight changes give better performance.

 

[Denny]

Relax buddy, the worst thing that could happen was a flying belt and I was wearing protective eye wear, not to mention I was giving it less then half throttle.

Ok genius, I’ll leave you alone now then since I obviously don’t know what I’m talking about.
Peace out…

 

[david-ab]

OMB Warehouse. The juggernaut won't help your problem of the driven opening up too quickly. You can also purchase ( from them ) lighter weights and stiffer garter springs for the driver. Much cheaper than the juggernaut and with different springs you can tune it to your liking. I have a juggernaut on one of my karts, and honestly the spring and weight changes give better performance.

Right now I have the red spring, what color do you suggest as an upgrade? yellow? and do I stick with the 30 series parts or do i need the 40 series spring?
Also a recommendation for a set of weights and garter springs for the driven pulley will be much appreciated

 

[panchothedog]

You do not need a 40 series. Everything you need is on their website. The weights in your driver right now are zinc. Buy the aluminum ones. Even with the stock springs it will raise engagement rpm to 3300. About 1000 to 1100 higher than it is now. They list the yellow spring as the stronger one for the driven. All of this is spelled out on their website. Go to go kart and mini bike parts. Click on to torque converters, then " more torque converter parts ". I am not very good with technology, and it takes me about 1 minute to find this stuff. You will not be disappointed with the results. Garunteed.

 

[panchothedog]

Your video shows the engine mounted on a piece of wood or steel. Do you currently own a kart that you are going to put it on?

 

[david-ab]

Your video shows the engine mounted on a piece of wood or steel. Do you currently own a kart that you are going to put it on?

Yes I do, the wood plate is a jig i make for the break in procedure.
This is not a new engine, I used it in my go kart, and took it out for the latest upgrades - the piston, the crank and the loop pipe.
why are you asking?

 

[panchothedog]

Was just wondering if you do modify your torque converter, will you have something to try it out on? As you specified in post # 1, your engine should be pretty hot. Capable of some very strong performance. Especially in the upper
rpm range. That is the whole purpose of tuning the driver to engage at a higher rpm.

 

[david-ab]

Just installed the engine back to my kart, and it seems the belt doesn't climb over anymore, although i didn't gave it full throttle yet.
Either way I ordered the yellow spring and a stiffer garter springs for the driver. and also a genuine belt, just to make sure the knock-off one I used is not causing any issues.
will update after I give it full send

 

[panchothedog]

The aluminum weights are a lot more expensive than the garter springs. But they make a bigger difference than the springs.

 

[david-ab]

The aluminum weights are a lot more expensive than the garter springs. But they make a bigger difference than the springs.

To be honest I consulted with the support team on the OMB website, they have an online support chat, and the guy really insisted that the aluminum weighs have less effect than the stronger springs
Worst case I'll order the aluminum weighs in a second order

 

[panchothedog]

Surprised he said that. Has not been my experience. But I know who you mean.
Eric Adams. The Grey Goat Garage. Can't tell you how many times that guy has helped me out, or recommend the correct part number for me over the last few years. He really knows his stuff, and if it's during the week always gets back to you the next day.