I can tell you anything you want to know about belt adjustments and all versions of automatic clutches available for the Whizzer motorbike. I was envolved in the early developement of the current automatic clutch offered by Whizzer. In fact I used the latest version on my 1950 Whizzer Sportsman with the modified NE motor and pulled "wheelies" on the starting line of the dirt drags at Dawson Springs, KY. I have tested the Jerry Lane version, the 3rd Mel. version, the 2001 autoclutch, and many different versions of the current production clutch. Here is some information you might find useful, the ratios are very radical on the Whizzer 2001 automatic clutch because of the large pulleys, and resembles taking off in second gear, however it works really great with a modified NE motor. The Jerry Lane clutch becomes very unstable at high RPMs and I have witnessed several snap the mounting arm. The 3rd MEL. version has a lower ratio than the current Whizzer offering [bike has less top end speed]and requires changing all the belts and the front belt runs between the belt guard mounting posts. I have had a few small problems with the bearings and getting replacement parts with the 3rd Mel. version, and because it isn't spring loaded and mounts rigid the belts require more adjustment, and the sheeve in the rear wheel better be really centered. And now my favorite of the automatic clutches, the current production unit from Whizzer. I like the way the clutch engages, it "slides" into full lock, and allows the motor to make more torque before total lock. Another reason I like the current clutch is because it is available in 3 different versions, the 90MM, 70MM, & 50MM, and ALL parts are available [bearings , seals, mounting arms, shoes, spacers, left & right side hubs, etc]. The new clutch is also very easy to service because of its simple design. If you elect to upgrade to the automatic clutch I suggest contacting your nearest Authorized dealer, or take Mike up on his offer to do some trading, my price is $236.55 plus shipping. Make sure you purchase the latest production clutch because the unit has been put on a diet and uses an aluminum primary side hub for better throttle response. The stock ratio is 90MM [3.54"] and would use the stock belts. The 70MM version uses a drive pulley size of 2.7559" and most likely would require a shorter rear belt. Don't even consider the 50MM version unless you wanted to climb the side of a building and a have a top end of 24 MPH @ 5000 RPMs. Now back to the standard clutch for a moment, I would move the rear wheel slightly towards the rear of the bike, or move the top of the motor slightly foward and the problems with the belt squeel should vanish. Like Mike said it is usually the front belt that makes noise, meaning the rear belt is just a tad too loose. If possible you might try replacing the front with an AX27 belt for better results.
Let me know if this information is helpful,
Whizzer OuterBanks,
Quenton