Clutch not engaging

[ShermDog]

Hi all- I’m back hoping to get some more help with the go kart rebuild. As mentioned in my prior post- my neighbor recently gave my kids two go-karts. One is a rattler II and the other is a rattler LXT. Both were sitting outside for a couple of years so a lot of tuneup and replacement of rusted parts. I swapped out the clutch on both of them with centrifugal clutches and new chains. On both karts they seem to engage when you give the kart gas but then lose power and doesn’t seem like the clutch is engaged or strong enough to move around. Because it happening to both, I feel like I’m doing something wrong. In hindsight- I wish I had gone with a torque converter instead and might still go that route but want to make sure I’m not wasting money if there’s a bigger issue. The clutch on one wasn’t cheap- I bought directly from comet and cost me 80-90 dollars…. My point is I didn’t buy a Chinese made POS on Amazon. Any ideas or suggestions would be appreciated. Thanks

 

[Edwin Spangler]

Ill respond here since this one has the pictures. I deleted my other reply.

Its the belts that you need to buy name brand, comet. Clutches and CVTs are not as important.

 

[Hellion]

What is the gear tooth count on both karts {clutch teeth and drive sprocket}?
What are the heights of the rear {driven} tires on both karts?

Count them, don't just guess or half-arse count the teeth and hope close enough will do. Mark the starting point with a Sharpie if you need to. We need accuracy.

Measure the height of the rear tires with a ruler/tape and at full inflation {even though the height is likely printed on the tire, don't trust it as it can be quite inaccurate}.

 

[Hellion]

This is required reading:

10 Things to Know about a Go Kart Centrifugal Clutch

www.bmikarts.com

 

[Hellion]

I am asking these things to determine your gear ratio.
If the gear ratio is abysmal and not ideal, you could be having issues with drivability and clutch roasting.

 

[ShermDog]

Apologies if I blew up the forum with multiple posts… the site was telling me that it had a technical error and to try back later… I had no idea they posted… that said
Neither had belts they are both chains. I matched the clutch and teeth count to the ones that were on them.
the LXT has 18 inch rear tires with a 11 tooth clutch
The R-2 has 12 inch rear tires with a 12 tooth clutch.

 

[ShermDog]

I definitely needed the “magic hammer” to get one of them on… I cleaned the shaft with emery cloth and oiled the inside but it still needed motivation to get onboard…
Also sharing the error I get went posting… not sure if others are getting the same..

 

[Hellion]

What is the gear tooth count on both karts {clutch teeth and drive sprocket}?

We need the tooth count on the axle sprockets too, that's the bigger one. Large sprocket divided by small sprocket gets you the gear ratio.
Kart 1 - 11 tooth clutch, XX tooth axle sprocket
Kart 2 - 12 tooth clutch, XX tooth axle sprocket

Also sharing the error I get went posting… not sure if others are getting the same..

Happens to all of us. We just ignore the error message, hit the X on it refresh and voila, the message posted. Yeah I know, it blows.

 

[ShermDog]

We need the tooth count on the axle sprockets too, that's the bigger one. Large sprocket divided by small sprocket gets you the gear ratio.
Kart 1 - 11 tooth clutch, XX tooth axle sprocket
Kart 2 - 12 tooth clutch, XX tooth axle sprocket



Happens to all of us. We just ignore the error message, hit the X on it refresh and voila, the message posted. Yeah I know, it blows.

Kart 1 - 11 tooth clutch 54 tooth axle
Kart 2- 12 tooth clutch 80 tooth axle sprocket

 

[panchothedog]

ShermDog, with 18" tall rear tires it will NEVER work with a centrifugal clutch. Well maybe a 10 tooth driving a 140 tooth. You need 30 series torque converters. Plain and simple. No two ways about it. The $60 cheapies on Amazon are as good as any. Do you know what size chains are on the karts. They will come with a 10 for a #420 chain and a 12 for a #35 chain. 10 X 60 is ideal. 10 X 54 will still work. You may have to change the 80. Try it. It will be pretty low geard. A stump puller. Depends upon terrain and driver preference.

 

[Hellion]

12 tooth kart with 12” tires should be fine with that gear ratio 6.6:1, but clutches also just love full engagement. The engagement RPM can be regulated and adjusted with shoes and springs. The article I linked is top notch in how you’re supposed to drive a centrifugal clutch. Clutches are better for racing….

With a torque converter, it just provides a variable gear ratio and they are better for lots of stop and go driving and low torque applications like trying to drive up a hill in low gear. They’re really quite amazing for what they are…

Pay attention to Pancho’s questions in particular.

 

[Denny]

CVTs are for high torque low rpm applications.

 

[ShermDog]

Hi all- sorry for my delay in response, I was traveling for a couple weeks in August.
I appreciate the advice and insight. I decided to go the route of the torque converter and have run into another problem. The drive shaft for the go kart that I’m working on isn’t threaded for a bolt to be inserted. Am I SOL or is there a work around that you can share. I can try and tap and die to create a thread but honestly not sure if I have enough space to work with. Thoughts?

 

[Denny]

It appears that a bolt is broken off in there. You will have to remove or drill and tap.

 

[panchothedog]

FWIW, use all 4 bolts to hold the plate to your engine. The whole force of the drive train is on there.