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 Rear pulley not opening completely 
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Post Rear pulley not opening completely
I have found why I cant go much over 30mph on the bugeye I am rebuilding. It seems like the rear pulley won't fully open, even by hand. As a result, the belt won't go up in the variator and I hit top speed WAY early.

I'm not exactly sure it's a pulley from which model. It's pretty much the same as the one I had on my bugeye, with what seems to be a 2009 date stamp on it. I got the pulley already assembled with a 3-pad clutch and a stiff red contra (which might be changed once the issue gets fixed; the CVT tuning seems dead-on if not for the pulley not fully opening). Not sure if the clutch is a stock 3-pad or an aftermarket one... there's no brand markings on it.

I have hand-tested prying the pulley open, putting a belt in, and compared with another pulley I have (also mounted using a red Contra and a MHR Delta clutch). One clearly allows the belt to go deeper.

I am using a stock Yamaha belt, for the records. It's not brand new, but it used to work well with my MHR Team.

What could cause the rear pulley to not fully open?


Crappy potato quality picture. I made a purple mark on the variator and went for a run. It's not really visible, but it's somewhat matching the "wear" area of the variator. I forgot to take pictures of the pulley, but nothing seems off about it. It just looks like your typical rear pulley with a 3-pad clutch and a red contra.

Image

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'94 Yamaha Jog - MHR BigBore 77cc, Yasuni C30, Stage6 HPC 12mm, MHR Digital Direct + EPROM 3 CDI, Dell'Orto VHST 28mm BS, Stage6 Big Valve intake, Stage6 NBR reeds, Malossi MHR Overrange 2005, Stage6 Torque Control + Stage6 CNC 450g bell, 14/46 primary gears


Tue Apr 22, 2014 8:32 pm
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Post Re: Rear pulley not opening completely
If you're not working with the rear clutch and pulley OFF the scoot at this point ... I'm thinking that you need to.

It's gotta open/close without any hang.ups.

Maybe it's needing a really good cleaning ?? ??

So ... the clutch doesn't have any slip ... it's the spring/pulley ??

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Tue Apr 22, 2014 11:16 pm
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Post Re: Rear pulley not opening completely
Yes, they're off the engine, but the pulley and clutch assembly is still together.

Clutch doesnt seem to be slipping... and as I said, when I try to open the pulley by hand and force the strap in, it won't go as far as another pulley I have around.

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'94 Yamaha Jog - MHR BigBore 77cc, Yasuni C30, Stage6 HPC 12mm, MHR Digital Direct + EPROM 3 CDI, Dell'Orto VHST 28mm BS, Stage6 Big Valve intake, Stage6 NBR reeds, Malossi MHR Overrange 2005, Stage6 Torque Control + Stage6 CNC 450g bell, 14/46 primary gears


Wed Apr 23, 2014 4:25 am
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Post Re: Rear pulley not opening completely
take it apart and inspect.. also clean it!

then re-assemble if you don't find any faults... and test again.

it must open... unless you have a piece crap stuck inside the pulley.

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Wed Apr 23, 2014 5:46 am
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Post Re: Rear pulley not opening completely
I havent taken it apart yet, because of the lack of proper tooling to open it up. Instead I tried another rear pulley assembly I had, that I know was working correctly (again with a red contra), and no dice, tops just under 30mph. So the pulley seems fine, but the CVT adjustments are most likely off the charts. I'm thinking the rollers are too lights and the contra too stiff for what's in there.


Rollers were at 5g (30g total), so I'm making a mix to bring them around 37.5g. Tomorrow I'll get some tools to open the clutch nut and change the contra to either a stock or white/soft one.

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'94 Yamaha Jog - MHR BigBore 77cc, Yasuni C30, Stage6 HPC 12mm, MHR Digital Direct + EPROM 3 CDI, Dell'Orto VHST 28mm BS, Stage6 Big Valve intake, Stage6 NBR reeds, Malossi MHR Overrange 2005, Stage6 Torque Control + Stage6 CNC 450g bell, 14/46 primary gears


Wed Apr 23, 2014 7:58 pm
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Post Re: Rear pulley not opening completely
so its not the rear pulley.

then the rollers are to light... or stiff contra.

also, maybe the rollers have moved... or worn?

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Thu Apr 24, 2014 1:35 am
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Post Re: Rear pulley not opening completely
I'm not sure what's going on, but your variator nut is screwed on too far. It should be flush with the end of the crank - there's just enough room to fit everything on and then tighten it.

I don't see the convex washer there, so maybe that's all, and in that case it doesn't affect how far the vario can close (and that's the issue - it's not closing enough, it's not that it's not opening enough!).

Do you have shims? Can you run without the shim washer?

Also, the belt normally doesn't go all the way up. But it should go farther up than that.

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Thu Apr 24, 2014 9:12 am
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Post Re: Rear pulley not opening completely
Replaced the contra for a stock one. I now hit ~38mph on the stock counter. Is that about how fast a stock 50 should be going? I never rode a stock one :eng101:

But the contra is too soft and it's hesitating when you hit a hill or get back on the throttle. I've put in a yellow contra (we had no white readily available) along with heavier rollers and tomorrow I'll see how it goes. I'll also see if I can get a new belt. The one i have is used and I dont know how many miles it has.


I'm waiting on completing my starter assembly so I can put it in there and finalize the shimming behind the variator. It's possible that it isn't correctly positioned, but this isn't a stock bugeye variator, and it works for now. Also, convex washer?

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'94 Yamaha Jog - MHR BigBore 77cc, Yasuni C30, Stage6 HPC 12mm, MHR Digital Direct + EPROM 3 CDI, Dell'Orto VHST 28mm BS, Stage6 Big Valve intake, Stage6 NBR reeds, Malossi MHR Overrange 2005, Stage6 Torque Control + Stage6 CNC 450g bell, 14/46 primary gears


Thu Apr 24, 2014 9:37 pm
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Post Re: Rear pulley not opening completely
Goshi wrote:
Replaced the contra for a stock one. I now hit ~38mph on the stock counter. Is that about how fast a stock 50 should be going? I never rode a stock one :eng101:

But the contra is too soft and it's hesitating when you hit a hill or get back on the throttle. I've put in a yellow contra (we had no white readily available) along with heavier rollers and tomorrow I'll see how it goes. I'll also see if I can get a new belt. The one i have is used and I dont know how many miles it has.


I'm waiting on completing my starter assembly so I can put it in there and finalize the shimming behind the variator. It's possible that it isn't correctly positioned, but this isn't a stock bugeye variator, and it works for now. Also, convex washer?

the convex washer goes between the castle nut and variator nut.
I think 38 is in the ballpark for a stock scooter--- may be a little slow.

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Fri Apr 25, 2014 4:39 am
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Post Re: Rear pulley not opening completely
38 is what my bike did stock.

Obviously you can use heavier rollers and a stiffer contra spring.

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'05 Zuma 50, Athena sport 70cc (12mm piston) with Polini head (.9 squish), B9ES spark plug; timing advanced about 2˚; Yasuni C16 exhaust, Buzzetti kick stand to make room for it (and Stage6 paddock stand after dropping the freaking bike because of the kick stand); stock airbox no snorkel, 5 x 1/2" holes; Stage6 21mm racing PHBG, 45/95/W7 1 lean/40 slide; Polini/Power One 12mm HPC crank; Athena 15/50 gears (also have 14/42s pressed into a gearbox cover, just switched back and like the 15/50s so far); 107mm Malossi Delta clutch, "racing" red springs/lighter "racing" counterweights ± 6800 RPM engagement, Stage6 Kupplungsglocke (bell - the light one); Malossi 6112811 Overrange kit, red contra and 28.2G rollers; VForce 3 reeds; Michelin Bopper tires; back to the stock shock; dual headlight wiring; C3 mirrors; Trailtech TTO tachometer and temp gauge.


Fri Apr 25, 2014 7:33 am
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Post Re: Rear pulley not opening completely
Goshi wrote:
Replaced the contra for a stock one. I now hit ~38mph on the stock counter. Is that about how fast a stock 50 should be going? I never rode a stock one :eng101:

But the contra is too soft and it's hesitating when you hit a hill or get back on the throttle. I've put in a yellow contra (we had no white readily available) along with heavier rollers and tomorrow I'll see how it goes. I'll also see if I can get a new belt. The one i have is used and I dont know how many miles it has.


I'm waiting on completing my starter assembly so I can put it in there and finalize the shimming behind the variator. It's possible that it isn't correctly positioned, but this isn't a stock bugeye variator, and it works for now. Also, convex washer?


You can check the belt by measuring the width. New is 16.6mm, wear limit is 14.7mm I believe.

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Fri Apr 25, 2014 4:27 pm
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Post Re: Rear pulley not opening completely
Firehawk989 wrote:
Goshi wrote:
Replaced the contra for a stock one. I now hit ~38mph on the stock counter. Is that about how fast a stock 50 should be going? I never rode a stock one :eng101:

But the contra is too soft and it's hesitating when you hit a hill or get back on the throttle. I've put in a yellow contra (we had no white readily available) along with heavier rollers and tomorrow I'll see how it goes. I'll also see if I can get a new belt. The one i have is used and I dont know how many miles it has.


I'm waiting on completing my starter assembly so I can put it in there and finalize the shimming behind the variator. It's possible that it isn't correctly positioned, but this isn't a stock bugeye variator, and it works for now. Also, convex washer?


You can check the belt by measuring the width. New is 16.6mm, wear limit is 14.7mm I believe.

Thanks, I'll measure it tomorrow.

Got the tuning down... used the softest yellow contra I had around (still stiffer than a stock), using my hand pushing it down as a comparison, and settled with 5G rollers all around. Pulls "hard" till top speed, and little hesitation when getting back on the throttle.

Now it's making some sort of.... hiccups... when I hold it at WOT. Like, brief hesitations. But I'm low on gas, could that be it?

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'94 Yamaha Jog - MHR BigBore 77cc, Yasuni C30, Stage6 HPC 12mm, MHR Digital Direct + EPROM 3 CDI, Dell'Orto VHST 28mm BS, Stage6 Big Valve intake, Stage6 NBR reeds, Malossi MHR Overrange 2005, Stage6 Torque Control + Stage6 CNC 450g bell, 14/46 primary gears


Fri Apr 25, 2014 9:20 pm
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Post Re: Rear pulley not opening completely
New strap helped a bit. Bogs a lot once well warmed up... it could be heating a bit. My engine cover isn't correctly fixed, so I'm gonna tie-wrap it better. I'm also going to try another variator, we believe this one sucks sweaty donkey balls.

A tuner friend also thinks it's running a bit rich. So we'll bring the jet down.

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'94 Yamaha Jog - MHR BigBore 77cc, Yasuni C30, Stage6 HPC 12mm, MHR Digital Direct + EPROM 3 CDI, Dell'Orto VHST 28mm BS, Stage6 Big Valve intake, Stage6 NBR reeds, Malossi MHR Overrange 2005, Stage6 Torque Control + Stage6 CNC 450g bell, 14/46 primary gears


Mon Apr 28, 2014 2:54 pm
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Post Re: Rear pulley not opening completely
Did you ever figure this out?

Im having the same issue with my rear pully not closing all the way. Only riding 50% of the way up the variator. 2000rpm spring, malossi multivar. Tried 4g dr pully rollers and and 6g rollers with little to no difference. Nyc rear pully. Too high rpms when WOT i can deff feel it.
When i try to close the rear pully by hand the belt wont go all the way down. Close to 50% of the way.

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