Belt help

#1
So, I’ve been slowly working away to get this mini bike together.
Got the engine sitting on it and trying to figure out how this all works with the “jack shaft?”.
I have a pulley on the predator engine and can line it up with the shaft pulley. Mine does not appear to have a tensioner. How does the belt stay tight?
I’m guessing the chain Should be easy to figure out.
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#7
I’ve been googling the crap out of this.
So the engine would have had some sort of pulley that drove a belt to that jack shaft, but I don’t understand what would keep the belt tight?
 

ELT

Active Member
#8
I’ve been googling the crap out of this.
So the engine would have had some sort of pulley that drove a belt to that jack shaft, but I don’t understand what would keep the belt tight?
Google comet torque converter. There are good explanations of how it works. A comet 20 or 30 series with a 6" driven pulley is what you need
 
#10
Ok, I think I’ve wrapped my head around this.
How do you go about measuring the belt length?
So, the driven pulley is original to the bike.
How freely should this spin? Like a freewheeling pulley? Mine turns, but doesn’t spin freely.

ETA: Pulled the shaft and the bearings are shot there too. The shaft was slightly misaligned as well.

I’m hoping to just buy a driving torque converter, but waiting to hear from the experts here to see if I need to replace this pulley too.
Got all my wheel bearings replaced today too. 7C61FBD7-C905-45EC-BB63-3E411E68051A.jpeg
 
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#11
Next fun task is putting new bearings on 2616E379-6F37-47FE-A2B3-D1F20C260B16.jpeg 98E92C17-2902-4CA5-99B4-5C65968759B7.jpeg 86FD7FC4-3C25-4D4C-AE71-69AE15FA722C.jpeg CBED1767-7F93-4283-A4B1-C7FD910139FE.jpeg D343A295-677F-4414-84F2-8C3256A7446B.jpeg 79513128-7B9F-4731-B91D-DF5AC5817AE3.jpeg my jack shaft which has an OLD comet driven pulley. It looks like it may be broken. There are 2 holes that may have been rivets? Anyway, the back 1/2 of the pulley can spin. Good, bad, normal?
 
#14
Ok, I got the torque converter mounted and put new bearings on the jack shaft.
My belt looks like it will actually drag on the frame. I'm wondering if the original engine had a crank centerline that was higher.
So, I think I will try to shim the engine up a bit to see if that will help.
 
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