Belt thickness

[dexameth]

So there's 2 versions of the QMB139 motor. Short and long case. Why is the belt skinnier on the long case? 17.5mm on the 729 belt, 18mm on the 669. I don't understand the reason...

If I have one each of these motors, and buy the exact same aftermarket clutch and variator, the short case will use a wider belt and the long case will be skinnier. 

I guess I may just be too bored at work...

[acvw74]

There is one other qmb139...extra long case. It has a 788 18 1 belt.

[jeff84]

math. that's all I can say. I'm bad at math

[jeff84]

if you can answer this question in detail, you should get a job as a cnc machinist or better.

[stepthrutuner]

Specs are often wrong. Especially with China scoots.