780 16 28 belt??

[miniquaddad90]

Anyone ever seen these belts? The only replacement I can find is a 30deg belt. Even stranger is this size belt was on a 90cc motor we got as a spare. I can tell that the belt was going all the way up the front variator so I am wondering whats gonna happen when I put the 787 belt on it. Any ideas why this would have an oddball 28deg belt or why someone would run the shorter 50cc belt on a 90cc?

Thanks!

[EthansDad]

odd. I've read up on groove angles, but never played around with them too much. your standard groove is 30 deg on the belt. your variator sheave halves should be 14 deg per side (giving 28 deg total). you can measure that if you have an angle finder.

bottom line on my best guess, a 26,28,30, 32 belt groove angle should all work. what you are playing with is friction coefficients (oh boy, another tuning variable!). less in contact with the sheaves (lower angle) the less friction, more angle, more friction. less friction means less power transfer at a given moment, and also less heat transfer. both should work, but my guess is that it will effect shift and possibly heat transfer build up too.

Try it, let us all know.


and 787 belts with 50cc have never been good to me. go for a 782x16x30, its nice!
-EA

[miniquaddad90]

Thanks for the help! Its actually a 16.5 wide belt, looked at it again last nite. Prob just gonna go with a 780 16.5 30 as a replacement since the current length seems to work good just a lil different angle I guess will be ok..... at least i hope

BTW-its a 90cc Kasea motor if it means anything, appears to have stock clutch and variator, I dont know for sure, TOTAL CVT newbie!

[EthansDad]

width and groove angle are different things and have a different effect on the CVT. a thinner belt takes longer to grab, then the angle effects the force to witch it grabs. think of a thinner belt as the same effect as shimming the variator halves. too thin, its just slips too much.

going from 16.5 to 16 is just fine as well.

-EA

[camsdad]

788/17/28 was the original belt for the kaseas it's still available,The780/16.5/28 is a yellow banded belt the Justin(max rpm) brought in from overseas a few yrs ago.it worked very well but you won't find any.

[miniquaddad90]

Originally posted by camsdad
788/17/28 was the original belt for the kaseas it's still available,The780/16.5/28 is a yellow banded belt the Justin(max rpm) brought in from overseas a few yrs ago.it worked very well but you won't find any.

THANKS! So any benefit going to 788? I have found Bando 780 16.5 30 belts locally

[EthansDad]

won't hurt to have a few sizes to try in your tool kit. for a 90, a 787x16x30 would (should) work nicely. the benefit to a longer belt (the first number is length in mm) is that it sits up higher on the pulley, effectively giving you a taller gear on both ends of the range. works nice if your motor can handle it. the 782x16x30 is a nice layup in the middle if your motor does not like the 787. I've had very similar motors that act differently to the same belt size. some like longer belts, some don't. good to have a few and an easy switch out to see what works best.

-EA