Belt Size

[OneTimeUser]

I have a Super 30 series driven clutch (great improvement by the way) on a stage one Tillotson 212--Nibbi 24mm straight pipe with screw on muffler.

Problems is that the shortest belt 27 1/32" (Comet 203589, generic 5959) is just a tad too long. This keeps my CVT from reaching its max gear (belt) ratio and, I think, robs me of some top end.

The housing for my driven clutch on my Fox cart is welded to to frame and not adjustable.

So, I'm thinking of taking up some slack by installing a spinning bushing (like the brass ones on the regular CVTs. The Super 30 does not come with a bushing.

Anybody have any ideas/experience with such a problem? I can machine a bushing of most any material and any thickness to take up extra belt slack.

Put on you thinking cap please. Thanks in advance

 

[Whitetrashrocker]

Are you referring to the brass bushing that goes on the shaft of the cvt?
If so, all that does is make the belt tighter at idle. Once the clutch starts to engage, the belt rises up. That bushing has nothing to do with belt length.

Is your clutch opening all the way?

Or are you talking about the secondary driven pulley.

Give us a pic we can look at man.

 

[OneTimeUser]

Yep, Bad idea that won't work. The problem is that the distance between my driver and driven pulley shafts is just a tad too short for the smallest belt I ca find. My driven pulley is attached via weld to the frame. I don't have a backing plate that holds both shafts.

I'm thinking now of moving the motor a bit further up to make the distance between pulley shafts greater.

 

[panchothedog]

Yep, Bad idea that won't work. The problem is that the distance between my driver and driven pulley shafts is just a tad too short for the smallest belt I ca find. My driven pulley is attached via weld to the frame. I don't have a backing plate that holds both shafts.

I'm thinking now of moving the motor a bit further up to make the distance between pulley shafts greater.

Yes, that would be the obvious ( and easiest ) solution. Is the motor mount plate slotted so you can do that?

 

[Whitetrashrocker]

Depending on how the cvt is mounted, one could put spacers under the engine if slots arent available.

But alas, OTU won't give us a pic.

 

[panchothedog]

A good 3/8" drill bit and a dremel tool with the good cutting wheels and I've made, and or lengthened my own.

 

[OneTimeUser]

OK, Here is a picture. Hard to tell from the picture, but the driven pulley's shaft is held by two bearings welded onto a tube attached to the frame.
I could elongate the holes and scooch the engine forward, but I'm concerned about the engine staying in place.

I think WTR's idea of washers under the engine is the genius move here. Adjustable, reversible, easy, cheap.

It's topping out about 96 mph now, I'm hoping to crack the century mark after tightening up the belt.

Wish me luck...

 

[Whitetrashrocker]

96mph! And your whining about top end?

Im kinda surprised you have the power out of that 212 to do that.

And yes, now that i can see your set-up, washers under the engine will make the center to center longer.

 

[OneTimeUser]

Just fooling of course about the 96 mph. It tops out at about 36. I'd like to get it up to about 45 without having to re gear. I like the low end acceleration it has now.

 

[Whitetrashrocker]

You could probably drop a few teeth on the rear and never notice the low end loss.

With the cvt you have like a 3:1 low ratio mas o menos multiplied on top of your chain ratio. Typical karts like 6:1. So your take off ratio is in the ball park of 18:1

 

[panchothedog]

Sliding the engine for and aft is very common. 4 bolts with lock washers and it isn't going anywhere. Spacers ( like bushings ) might be a little more stable than a stack of washers if you decide to raise it.