CVT belt angle and the Dr Pulley Variator

[Lostmycage]

Ok, so this one's been bothering me. The Dr Pulley variator is a "universal" GY6 variator that's made to fit a large span of GY6 engines. Thing is most GY6's have a 30 degree drive belt whereas the Blur 150 and the Buddy 150 both use a 28 degree belt. I know it's only a 1 degree difference per belt face, but I opened up the CVT this weekend and I noticed a considerable amount of dust.

Has anyone else that's installed a Dr Pulley variator opened their cases to check on it a few hundred miles after installing? I'm wondering if I've refaced my belt and maybe this is why the difference isn't immediately noticeable upon initial installation.

Now I know there's a bit of a shortage of belts available for the Blur (I'm not seeing the Buddy 150 either). The Blur uses a special sized belt that a little off from the normal but I was doing some thinking... more later.

Does anyone know the angle facing of the Driven pulleys? (the one in the clutch housing). Did they make a special 28 degree pulley just for the 150s? I'm trying to pin down specs on the PGO 150cc's.

So here's the questions:

1) How much of a difference will 2 degrees have on the amount of grip that the belt has on the pulleys?

2) Would a 30 degree belt prolong the life expectancy of the Variator and give better performance?

3) Could we find a driven pulley that has a matching 30 degree face and convert the entire system to a more commonly available belt angle?

4) Since the length is still an off size, here's the last question, and it's a good one: If we used a longer belt (and a stronger clutch spring) wouldn't the drive pulley be able to attain a higher gearing and therefore giving a little bit better top speed or more efficient cruising? The clutch spring would combat any want for the belt to hop too high and ride on the outside edge and possibly fraying or worse coming off the variator altogether. Ideally the belt would travel to the top of the variator and bottom of the driven pulley with no slack.

Thoughts, questions, comments?

[charlie55]

As I reported in the "PO'd" thread, I had found an 815 x 20 x 32, which would have been +2 degrees on each side of the belt. When asked, the seller was pretty sure that it would work, but that it would wear out faster.
So I guess that'd hold true for +1 degree, but to a lesser degree.

In my searches for an aftermarket replacement, however, I came across a Bando belt for a Majesty (Model YP125). The dimensions are 816 x 22 x 28. As you can see, the angle's dead on. The +4mm length difference should be of little consequence, and the +2mm on the top width may not be all that much of a big deal. The reason I feel that way is that the G-max service manual lists the nominal width as 20 - 21mm, with replacement suggested at 19mm. So, I don't think that going 1mm over the specs would be all that risky.

If you're interested, you can find the belts on eBay. Just search for yp125. IIRC, they're sourced from Taiwan and run about $14.00 plus $9.00 shipping.

I've been through the Gates, Bando, and Dayco catalogs, and it appears to me that the big hangup that makes this baby an oddball is the length (812mm) since there seem to be a lot of other NNN x 20 x 28 types out there. It's even got me thinking about rigging a small adjustable idler pully in the case. Not spring-loaded, since that'd probably interfere with variator - clutch interaction. Just something with enough leeway to be able to take up the slack in a larger belt.

[illnoise]

Again, not to be snarky, but has anyone actually asked a dealer about OEM belts? I asked POCphil a while ago and he said he had them in stock.

[Lostmycage]

OK, sorry, I might have used the wrong example there...

Basically, what I'm saying (OEM availability completely aside) is that I have the Dr Pulley Variator installed. I can't find anything specific on it just yet as to the pulley face angle, but since it's a "universal" and most GY6 150cc's have a 30 degree angle, is there a 30 degree angle in the 812ish range that I can use (possibly changing out the driven pulley for a true 30 degree as well) so that the belt and pulley faces match perfectly. I know 1 degree isn't too far off, but I'm a nut for precision. I also think it'd lead to a little more grip if the angles matched perfectly.

I'm basically pondering on a "performance" CVT system build.

I'm also concerned that since the driven pulley is potentially different (still unconfirmed to it's actual angle) than the Dr Pulley (again, this is as yet unconfirmed) face angle that it might potentially cause the belt to be constantly "shaved" down as I drive, leading to premature failure.


For stock belts, GY6stroker made a post in the for sale section about being able to get the Gmax 150/200 belts to us in the States. I think he can get them but I didn't see them at the time that I looked.

http://stores.ebay.com/Scooterista-Shop

I'm looking at replacing the OEM with a more universal and readily available belt (preferably Kevlar).

[jfrost2]

Just a notice, when you put a aftermarket belt in, and it's brand new, there will be alot of dust because of the initial wear it gets from the transmission. It will wear some and then be fine for a long time.

[Lostmycage]

Just a notice, when you put a aftermarket belt in, and it's brand new, there will be alot of dust because of the initial wear it gets from the transmission. It will wear some and then be fine for a long time.

Right, that's expected.

My concern is over the stock belt producing more dust than it has in the past. The thing I'm worried about is that the performance part is over-wearing the stock belt. I know it's only 1 degree per side of the belt, but if the driven pulley remains constant 1 degree off from the variator, the potential for wear is a lot higher.

I'm looking for input on those that have done the swap as well. The Dr P variator is very nice, but I'm trying to calm my concerns on excessive wear (stock or aftermarket belt).

If anyone has some solid findings on either side, I'd love to hear them.

[Spinergy]

The CVT belt pitch issue here is much like one you run into on cars which have non-stock pulley combos due to the swap-out of an alternator, ps pump, ac compressor, etc. If given the choice between a belt that's a hair too wide vs. one that's a bit too narrow always go with the wider belt. It will wear faster initially but that's just the belt "breaking in" to the pulley's pitch. Once that's over it should work just as well as a correct pitch belt. Go a bit narrow and you risk more slipping from the get-go, and having a thinner, weaker belt once it's worn in.

As to length; since the CVT unit is inherently "adjustable" a few mm won't make much difference. It will throw off the effective gear ratio a tiny hair's worth but that's it. Over it's life a CVT belt will stretch several mm just from normal wear, so if anything you might want to go with a combo that a hair shorter than stock. This all assumes you can't ever get a stock belt

Hitting the redline? Ever been on anything with a CVT when an old worn belt started slipping or worse yet failed?? The sounds can be very scary.

[cyclemotion]

After much crying and moaning about belt availability like the rest, I found a guy on ebay that has availability of (but does not list) a Bando 816 20 28 belt. He checked with Bando and they spec this belt as the replacement for the GMax-TRex application. It's about 3/16' longer but in the overall scheme of things it not much (.0049). As noted elsewhere the 812 belt is PGO specific and probably only available from PGO/Genuine dealers, if then. He sells a lot of other performance stuff like 4 valve heads and big bore kits but I prefer going stock as I have been that route in the ol' MX days. Best of all is the belt is $12 and shipping from Taiwan was $10 for two. Search/write Autotech355 on ebay and tell Carlos(??) I said hi.

[charlie55]

Thanks for the heads-up. As for my quest to go the "Genuine" route, it's still a tale of woe. My original dealer was de-listed by Genuine, so I tried emailing and then later (as suggested by others on the forum) phoning a couple of other dealers (neither of which are close enough for me to visit). The emails were ignored and the phone calls were either unanswered or dumped off to an answering machine.

That said, I contacted Genuine directly and explained the situation. They were kind enough to hook me up with Scooterworks, requesting that they handle the matter directly (something they normally wouldn't do, and for which I tip my hat to them and Genuine). So, I ordered two belts, an air filter, and a fuel filter. Waited a week without response, and was then told that they were waiting for the parts to come in. Fair enough.

Coupla days later, I was informed that the parts were in, so I told them to go ahead and charge my card and ship 'em. Okay so far.

Got the parts last Friday. Fuel filter: check! Air filter: check! Belts? Well, they sent me two belts for a Buddy, not a Blur. So, I'm gonna have to go the RMA route and hope that they get it straight on the next go-round.

I tell ya, I've had my eye on a couple of old Honda Rebels that are on the market, and I'm pretty close to buying one for a song (since we're going into winter and the prices are dipping) and then unloading the Blur in the spring when prices tend to rise.

I love the Blur, but this parts situation, despite what I would hope are everyone's best efforts, is more than I'm willing to put up with.

[NathanielSalzman]

FYI, on anything pulley/belt driven, having the belt too tight will wear the bearings out on one end or the other. It's got to have some slack in it or you'll wear the bearings out of either your crankshaft or your final drive, which would suck hard in either case. A couple mm probably won't get you there, but just be careful.

[charlie55]

Thanks for the tip.

Time for another status update in the never-ending saga of "Lord of the Belts".....

As previously noted, I received the wrong belts this past Friday. I immediately emailed my contact requesting an RMA number and an E.T.A./price quote for the Blur belts. Given that the weekend was starting, I didn't really expect to hear anything before Monday afternoon. Monday came and went, as did Tuesday. Finally, I sent another email on Wednesday and received a reply stating that my contact's parts guy at Genuine was on vacation this week, but that he'd try to find something out from his "tech" guy. No mention of an RMA, so I had to goose them again. So far, it's Thursday and there's no further progress.

Amazing, absolutely amazing.

[charlie55]

Looks like the saga is coming to a satisfactory end....

Genuine/Scooterworks has the belts in stock! Don't know how many, but I ordered two for myself. Additionally, I was informed that, in order to make up for the confusion and aggravation, they'd do a straight swap for the Buddy belts (which are less expensive that the Blur's), not charge me for shipping the two replacements, and also have UPS pick up the RMA at no cost to me.

Well, I gotta give credit where credit is due. It's been a tooth pull, but in the end Genuine and Scooterworks showed themselves to be a stand-up bunch of guys. Kudos to them.

[Lostmycage]

My dealer told me a day or two ago that she's getting Blur windshields in... and she knows well enough not to jump the gun on Genuine's promises of "it's on the way". It looks like Genuine and customs are finally getting caught up with their surge from this summer. I guess the beautiful fall foliage isn't the only good thing about this time of year for us.

Charlie55... I know you've been at wit's end, but if you enjoy riding the blur, you might want to think about holding onto it a little longer. I know you've had a lot of the same grips I have about parts and it looks like they're getting answered in short order. I love my Blur.... hell, I even took a hit on the insurance check to make sure I get it back.

The Buddy's been a great stand in, though. It's still a shame that we're selling it.

[bicyclerider]

Again, not to be snarky, but ....

I just like the use of the word Snarky