2009 Zuma w/ polini hi-speed variator -- belt length

[drumstyx]

another silly question!

What are you Zuma folks running for belt lengths? The OEM belt that came in this thing was the listed-spec 738mm, but seeing that I was nowhere near the outside of the rear pulley, I put an Athena 751-16.5 on it...I'm still a good 4.5mm from the outside of the rear...

I'm watching those homemade overrange variator videos on youtube, and I notice that his Minarelli "clone" engines are using 788 belts, which I see are stock for the 4 stroke Zumas.

I ran a fabric tape measure around the belt as-installed, to verify its length at 751 -- yep, that's legit. I've got it shimmed pretty well perfect so the belt is just about touching the variator boss, so I ran the tape measure along the belt at the front, but around the outside of the rear pulley, and came up with 765mm, which is stock on some Peugeot scooters apparently. Unfortunately, I can't seem to find a North American supplier of these belts, since I don't think we've ever had Peugeots in North America.

One thing to note: this belt is 8.1mm thick, so while I don't mind a thicker belt, if my math is right, I'd need an extra ~3mm in length per 1mm extra thickness.

How the heck is 49ccscoot running a 788 on a Minarelli? I guess our engines ARE different though, since my CVT cover doesn't have a support bearing.

Any ideas for a good belt length here?

[ryan_ott]

You’ll find some good choices in here:
49ccscoot.proboards.com/thread/24543/top-performance-td-belt-length

[drumstyx]

Apr 20, 2022 10:21:25 GMT -5 ryan_ott said:

You’ll find some good choices in here:
49ccscoot.proboards.com/thread/24543/top-performance-td-belt-length

OOOOO yes this is a great read, thank you! I see you're the OP on that one -- you mentioned a 764mm belt for an Aerox, but I can't seem to find that (at my canadian vendor at least). Got a link? Part number even? Any vendor that'll ship to Canada would work, just that North America is better on shipping

[benji]

Apr 20, 2022 10:13:23 GMT -5 drumstyx said:

another silly question!

How the heck is 49ccscoot running a 788 on a Minarelli?

there are several motors minarellis made, including 3 (at least) different versions for Yamaha/MBK. Jog style is considered a short block, and runs a longer belt due to the final drive configuration.

Just be glad you don't have an Eton.

[ryan_ott]

I’m not sure what the number for that 764mm belt was. Here is a list of belts. Maybe you can find a good match in there. I do know what belt you’d need with the 122mm pulley..
webmotors.hu/shop_ordered/2914/pic/meretek/Scooter-belt-catalogue-Dec-09-1.pdf

[Zino]

With the polini variator and malossi variator .
I actually got to 2mm left with a stock belt .
The right size shims and just the right weight of weights .
With a street pipe or Stock pipe I was 6 grams with the polini and above to get the travel.
With the expansion pipe tecnigas next r and yasuni r I was between 5 and 6 grams .

Manufactures measure belts difference I prefer to roll them out
Here is a thread where we discuss belt lengths
49ccscoot.proboards.com/thread/28919/malossi-belt-size-verification

[nickatnight]

Apr 20, 2022 15:23:13 GMT -5 benji said:

Apr 20, 2022 10:13:23 GMT -5 drumstyx said:

another silly question!

How the heck is 49ccscoot running a 788 on a Minarelli?

there are several motors minarellis made, including 3 (at least) different versions for Yamaha/MBK. Jog style is considered a short block, and runs a longer belt due to the final drive configuration.

Just be glad you don't have an Eton.

quick question, why should he be glad he doesnt have an eton? sincerly an eton owner