Malossi Multivar & belt advice!

[dan v.]

I tend to disagree with that.  I have noticed on mine that you can usually turn the torque driver and the belt will only have slight friction on the variator boss and drive faces. (upon shut-down).

Think about it - as soon as the engine revs up slightly the variator drive faces will close up and grab the belt. So a millimeter one way or the other can make a difference.

True, we are splitting hairs here. 

That's why trying the shims will make sense.   Be interesting to see how the shims and longer belt work out when they arrive.

[TBR125]

The clutch pulley faces are under constant pressure by spring tension. The pull of the belt presses the faces apart against the spring, therefore, when the belt losses torque(when no power is applied) the faces press together and press the belt with the same potential energy stored in the spring(minus loss) which maintains belt tension due to the v-belt's use of the equality of circular width. We may not be referring to the same part of the variator however.

[dan v.]

You are correct about the action of the Torque Driver or Driven Pulley as they are called, TBR125.  That assembly is always under spring tension.  It is the big pulley system that is close to the rear wheel, and the clutch is attached to it.

The variator - the pulleys at the crankshaft end - closes up and tightens on the belt with centrifical force only.  That is the end of the transmission where the belt can be slightly "loose" when the engine is not running.

People will often call these things by the incorrect name, like clutch.  It can be a bit confusing. 

[Parkmice]

For test purposes, I ordered a 748mm Gates belt and installed it. Just got back from a road test. It seemed to not big as badly when taking off from a stop. I topped out at 36mph according to my Waze app, and I had an eBay tach attached, showing about 6800-6900 rpm through shifting. The belt now sits almost all the way up in the driven pulley at rest, and my variator sharpie test shows the top maybe 3mm is not rubbing off, so I might be giving up a little top speed there. (Remember that with the 736mm belt I had absolutely no sharpie left on the variator anywhere).

I ended up not ordering or installing any shims. My thinking was that with the 736mm belt rubbing so much against the boss, that adding shims would probably not cause the belt to come away from the boss much, therefore not give the belt much room to expand out in the driven pulley. Also, I had pretty much perfect sharpie on the multivator, and thought shims would probably only serve to limit how far out on the multivator the belt could ride. Am I right about that?

The scoot is used in a hilly area. Who thinks I should stay with the 748mm belt? Who thinks I should go back to the 736 belt?

See attached pics:

[JJJoseph]

I'm going to be the odd man out in this discussion by saying it doesn't really matter which belt you use.  It only takes 20 minutes to swap belts, so try one and if it runs up to speed stay with it.  I've got a box of belts in my shop, and I just grab any belt that looks about right and install it. The variator adjusts to fit, so it's likely both belts will give the same result: 36mph.  The most important pieces are the movable drive face, the rollers, the plate, and the slides.