MOPED ARMY

Maybe it's slipping too much to begin with because there isn't sufficient tension, or the grunt of the polini is too much and just slips the belt off the line? That would chew through them pretty quick.

It's possible that texturing the pulley surfaces could help the belt stop slipping and eating itself.

Maybe you could increase belt tension a bit by getting creative with the pulleys/variator.

On top of making it easier to start, running one ring would tame it a little and maybe it wouldn't be so hard on the belts.

When I put them on brand new they are super snug and the bike will start quarter kick no problem, that’s what I’m trying to figure out. I did see the dos belts are a-20 belts and not ax-20 and from what I understand the ax belts are a bit tougher? It maybe all these after market boys are just a little too big? Maybe once they settle in from new the get too loose.

look for a wider belt, let me know whatcha find, ill be messing with one next year.

Is it possible when you milled the cheeks you didn't keep the angle and contact area with the belt correct? It looks to me the belt is wearing most at the outermost edge. The bottom of the belt looks not worn at all. Check your belt contact area and compare original cheek angle to your modified ones.

So I flipped my belts “inside out” and I noticed the inner taper is way off on these dos belts. The ribbed belt is the stock pirelli belt. It’s from the 80s and I’m pretty sure the bike had like 1000 plus miles on it from the ODO when I got it if I remember correctly. I’ll double check tomorrow but even age could cause shrinkage I was getting anywhere from 8.5-9 mm I’d bet new they were 9.2mm.

The new DOS belt (smooth) is significantly thinner. Both belts outer “wider” edge is 13mm so the taper is way off and it’s deff not gripping the way it should. I’ll contact dos about it and see if I can get some of their nos pirelli belts if I send these back.

For the unknown angles I get inverse tangent (7.5/1.75)=76.9 degrees for the top one and inv tan(8.25/3)=70.0 degrees.

The other point I recall about V belts is that when they're bent around a smallish radius their sloped sides bulge out. This enables them to grip the flanges of the pulley more effectively than a simple wedging action would. Now, I don't know if wear on a V-belt will affect this extra grabbing ability, and the changing effective radius of your variable pulley will add complications as well.

Personal note: I have learned a great deal about power transmission in highly-stressed machinery. I attributed some odd behavior in mopeds and motorized bicycles to changes in technology and material. However, my short but observant spouse suggested that I factor in a significant increase in gravitational force upon my no-longer-so-youthful body. "I'm surprised it got up that hill at all," said she.

Mark Kinsler

she is an amazing cook, so it's not entirely my fault.

I think it's a significant change in angle. These variable-V-pulley transmissions are used in hundreds of applications, perhaps the most common of which are washing machines, which during the spin cycle must accelerate a load of wet laundry from zero to fast with a smallish motor every few days for years. They're also used in tiny diesel cars that you cannot buy in the US, but which have been popular in Europe and I want one.

Clearly further research is needed, and perhaps a website that features discussions and tutorials on industrial power transmission would be a good place to start. I haven't tried it, but maybe the Google search terms "Industrial V-belt wear" might help.

Mark Kinsler

So I put a little oil on the stock belt and it brought the old letters to life I could seriously not read any of this before hand (well, barely any of it)

“pirelli” logo. Followed by “secto flex” then the belt was actually stamped “minarelli”

Now here’s the fun part, the numbers that I don’t know how to decipher,

Looks to be 7254/0 (Or “D”)

Followed by 1702049 6B

Even still I’m not 100% sure it’s all my issue is. I feel like extra pressure is getting out somewhere it should not be, it I figure even if my front is not maxing out. That should not cause “extra stress” on the belt. Because if the front is not maxed out there’s no way the rear is maxed and “pulling” on the front. It does not make any sense

Blake from dos got back to me, he’s super rad and is ganna let me try one of their pirelli belts out even though that one even does not match mine. These are uncommon engines but I love them and I want to get to the bottom of it, I’m trying to relate it to my one way bearing mod but I can see at all how it would stretch the belt (edited)

Alrighty folks, more news.

So, I learned tonight, there are two kinds of rear vario for a c2!!!

Well one part is different, the plastic bit! And this MIGHT be a part of my issue.

Here below you can see the two styles. Mine was the top, with these super cool sharp ass rivets. The bottom is a spare I had. Ignore the red for now.

Okay, so if you read this whole thread, you’d know I milled the spacer on the front vario to allow the front cheeks to close more, granting more belt travel. That’s cool, except what happens to the rear then? It must also give more and spread open wider to take up slack. The belt itself going lower than the ware line on that photo above and it’s possible the bottom of my belt is getting chewed up on those rivets. This is a theory and I can’t prove it as there’s not enough miles on it to show a new belt line on the rear cheeks. **** see a little side note about this as well at the end

So to help alleviate this I’m going to switch the the black plastic jawn. The cheeks themselves are different, so I’ll switch the whole inside cheek over. But also, since the black plastic piece just sits in the cheek, I’d assume you could actually grind those rivets flat and have no issues. What’s left of the rivets should act like posts to hold it in place the same way the black plastic piece does with the three black oval shaped nubs.

A little something else I’m going to try, this relates to the red circles in the last photo.

In the second photo what I circled is the same piece I have circled in the third. It’s a spacer to not allow them to close any more, I’m going to try and grind that down on the lathe just a hair to get rid of half that gap or even make them touch. This will make the rear belt ride higher at idle and apply more force to the front vario. Maybe not letting it slip?

To be honest I talked to Parker about his polini and Gila c2 builds. Both run the decompression valve head and he’s selling me one. I feel like this will actually alleviate the problem more than anything. Belt can’t slip if the compression is 0 haha ¯\_(ツ)_/¯

**** regarding to the stars earlier this is a little bit of a tangent. I also talked to Parker about windowing the front vario to get full use of the front cheeks, he has and he still can’t get the belt all the way to the top of the front. I feel this might actually be part of the back vario restriction, the plastic piece in question on this whole thread acts as a stopper, the front might actually max out because the rear can’t go any further. I’ll continue this post below so I can upload another photo to explain.

I couldn't find a manual but only did a quick search.

Theres a diagram in the wiki

I rebuilt a v2 without any special tools, you should be fine with the tools and pullers you've got. As always, don't lose anything and take pictures as you go.

Try this.

Shim the movable vari cheek so it’s tighter at rest.

This is a common problem on hobbits.

You shim the vari to push it in farther taking up slack so the belt is tight af in the cheeks and you can pedal start.

I doubt it’s the belt angle. Belt angle in my experience isn’t that important, like almost at all.

The test for this is if you can spin the vari by hand at all when the rear pulley is locked. If you can spin the vari you have to shim it or get a wider belt.

On hobbits the shims go between the vari and ramp plate to push the vari in further at rest. The shims float on the boss.

Hope this helps. (edited)

Also custom seat (I got a Guy)

got a NOS rack

Got some metal blinkers

got some rear holders for the blinkers(treatland)

new kickstand

NOS fuel tank (Treatland)

Nos Fuel caps (719 and 459) Score Treats

More pictures to come

in the spring

Scottie:)