What size is your drivebelt?

Irishrover · Post by **Irishrover** » Fri Jul 24, 2009 12:23 pm

Just curious to know if anyone has changed their drivebelt on the Buddy 125 and if so what was the stock size? Just checked today and my stock belt is a Bando 812 20 28. I bought a 814 19.5 a while back and wonder if this will work, not much in it as you can see. I would like a Gates kevlar but haven't managed to source one.

Lostmycage · Post by **Lostmycage** » Sat Jul 25, 2009 5:54 am

The Buddies have a much different sized drive belt than the Blur/Gmax. 812 20 28 is also the stock drive belt size for the 150cc Blur/Gmax. I think the Buddy 125cc is specced at 743 20 30. I'm not sure about the Buddy 150... for some reason I have it in my head that it's a different size, but I can't find any of my notes at the moment.

I've experimented with a few different sized belts as well, mainly because I'm worried about finding our stock size in the future. The 835 20 30 *almost* works, but I need to do more testing on it as it slapped the case at idle with the set-up that I was running it with (different rear driven pulley than stock). It seemed to do well with the stock rear driven, but I wouldn't recommend it without further testing. I'm in a "no mod" mindset of late and am just enjoying riding. Sort of like a "Stock Sabbatical" lol.

I'm going to recommend to the Mod's that can do so to shift this to the Blur forum, since the drive belts for the Buddies are so different in length and readily available.

davelhunter · Post by **davelhunter** » Thu Aug 13, 2009 9:21 pm

I just ordered an 821x20x30 belt, which is a little longer than stock. I noticed that even with heavier weights (14g) my belt still was not going all the way to the top of my variator, causing me to not get the full potential top speed. I should have it by Monday and will let you know how it works out.

illnoise · Post by **illnoise** » Thu Aug 13, 2009 9:50 pm

You said "buddy" in your post, but I think you meant "blur" since you ride a G-Max and you're in the Blur forum. If you are actually talking about a Buddy (BuBu) let me know and I'll move this to the Buddy forum.

Irishrover · Post by **Irishrover** » Thu Aug 13, 2009 10:10 pm

It was posted in the Buddy section, but no-one replied so I deleted the post and made a new one in the Blur section. I originally meant Buddy as it is similar to the G-Max 125 engine as I assume you don't get the Blur 125 version in the states. No need to move, thanks.

illnoise wrote:You said "buddy" in your post, but I think you meant "blur" since you ride a G-Max and you're in the Blur forum. If you are actually talking about a Buddy (BuBu) let me know and I'll move this to the Buddy forum.

davelhunter · Post by **davelhunter** » Mon Aug 17, 2009 6:15 pm

I ordered an MRP 821 20 30 belt from MRP. It is not true to size. It was actually SHORTER than the stock belt. Scratch this off the list of items to order for the Blur. If anyone else can find a belt by another company in this size, please let me know.

Lostmycage · Post by **Lostmycage** » Mon Aug 17, 2009 8:14 pm

Was it a Gates belt or an MRP belt? I was told that the 821x20x30 Gates belt is ideal for use with an over-range variator, but I can't find that anywhere.

I've also been thinking about trying out an 828 belt. I've put that project on hold because belts are stupid expensive, at least for "testing" purposes.

davelhunter · Post by **davelhunter** » Mon Aug 17, 2009 8:36 pm

It was an mrp belt. I have been unable to find another maker of the belt in this size.

charlie55 · Post by **charlie55** » Mon Aug 17, 2009 9:09 pm

Found an 815x20x32 on ebay:

http://cgi.ebay.com/815-20-32-CVT-Drive ... 286.c0.m14

Don't know how good it'd be, but it's only 3 mils off on the circumference, and 2 degrees each side on the angle.

Also, here's an 821 x 20 x 30:

http://74.125.47.132/search?q=cache:xQO ... clnk&gl=us

And, an 820 x 20 x 30:

http://scootertronics.com/sccvtbe25sc.html

davelhunter · Post by **davelhunter** » Fri Aug 21, 2009 7:14 pm

I just got my 821/20/30 gates belt. It is about 1/4" shorter than the stock belt. I am beginning to think that our stock belt is not true to size. I measured the outside of the stock belt with a piece of string. It measures
32 & 1/8" which converts to 815.97mm, so I am really confused. If anyone wants to measure their stock belt for comparison purposes and post results that would be great. In the meantime I am going to order one more time. i am going to try an 835/20/30 and see what happens. I will post back with results.

Lostmycage · Post by **Lostmycage** » Fri Aug 21, 2009 8:16 pm

835 will slap the inside of the CVT case at idle. I speculated that it would cause premature wear/failure of the belt and replace it with a stock belt. The 821 belt that I tried was also shorter than stock.

I've got an unused stock belt at home, I'll take a measurement of it and post it later this evening.

charlie55 · Post by **charlie55** » Fri Aug 21, 2009 10:05 pm

Dave:

Your measurement of the stock belt agrees exactly with mine - 815.975mm.

Going a step further, the OEM belt (812x20x28) is stamped with a fourth number, 9.5, which I have determined to be the depth of the teeth (actual measure was 9.55mm).

So, I got the diameter to the outside surface of the belt (C = Pi x D) and it turns out to be 259.628mm. Subtract twice the depth of the teeth from that and that leaves you with the diameter to the innermost part of the teeth (240.538mm). Plug that back into the formula, and the inner circumference comes out to 755.945mm (29 and 3/4").

So, I have no idea in hell as to where they get that "812" figure from.

Lostmycage · Post by **Lostmycage** » Sat Aug 22, 2009 4:54 pm

OK....... so here's something weird. I measured the stock belt (a spare-never used) and I came up with 827mm. I double and triple checked and it was 827mm.

When I measured the Gates Powerlink 835mm belt a while back, it was 842mm on the outside.

Moral: Belt's are liars!

babblefish · Post by **babblefish** » Thu Sep 03, 2009 8:28 pm

I haven't verified this, but they may be measuring either the inside diameter, or more likely, the "middle" circumference, i.e., from the middle of the belt thickness.

Modern Buddy

What size is your drivebelt?

What size is your drivebelt?

MRP 821-20-30 belt is labeled wrong, not true size!

Ordered another 821/20/30....it was also SHORTER than stock!