Minarelli high rpm clutch springs?

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Minarelli high rpm clutch springs?

Postby ohiotj » Wed Jul 16, 2014 7:55 pm

I recently picked up a scooter with a minarelli engine with a 70cc big bore kit and some other upgrades. The clutch shoes have been lightened a bit. I haven't taken it apart yet to check, but I think it is running NCY 2000 RPM clutch springs.

It is extremely slow on take off. It appears the clutch grabs at around 3000 RPM, and it very slowly accelerates until around 4000-4500 RPM. At that point, it gets very fast. Its not a street bike, so it doesn't need to run at low RPMs. I've done some looking, and can't find any stronger clutch springs. Do they exist somewhere? I'd like to be able to launch it at at least 4000 RPM. With how fast the engine revs once its in the power band, I'd rather not lighten up the rollers, but could try that if there's no other solution.

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Postby fluffynat05 » Mon Jul 21, 2014 7:45 pm

Last edited by fluffynat05 on Thu Jul 16, 2015 9:51 am, edited 1 time in total.

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Postby Areomyst » Wed Jul 23, 2014 9:17 pm

If you have exhausted the options with simply replacing the clutch springs, then replacing the actual clutch would be the next logical choice. You can modify the stock clutch by lightening the shoes to make it start to engage at higher RPM but as you go lighter you can also run the risk of it being too light and you'll experience a lot of "slipping" from your clutch.

Lately I have used a lot of Stage 6 Torque Control clutches, and the Polini 2g clutch as well. For typical street use, I really really like the 2g clutch. Evne though the documentation that comes with the clutch stresses not engaging it above 8000 RPM, I have done so successfully a few times now and the clutches are still working quite well.

On my drag racing engine I use the Stage 6 Torque control. I had problems with it slipping. At the advice of a friend, I tried installing the tungsten weights that you can get for the torque control clutch and it was a whole different animal.

Can you tell us more about your engine's setup?

"The more a man learns, the more he realizes how little he knows."

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Postby ohiotj » Sat Jul 26, 2014 9:15 am

Not entirely sure of the setup, since I picked up the bike pre-modded. The pipe on it looks like a race style pipe, but I can't confirm, I'm more used to playing with 4 strokes. It's a Leo Vince TT. No idea what 70cc kit is in it, but I think it has a stage 6 reed cage of some sort, and NCY 2000 RPM springs in the clutch. I also haven't pulled it apart to check the variator weights. I was told the clutch shoes have been drilled.

On fluffynat05's advice, I tracked down some Malossi and Polini racing spring sets, and they should be in sometime in the next week. I'll start there, since the bike free revs in low rpms way better than it accelerates. I think it's just not making any power until somewhere around 4K RPM.

Both of you, thanks for the advice so far.

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Postby ScooterZombie » Thu Dec 25, 2014 9:00 pm

You could try some lighter roller weights- along with what the other members have suggested- depending on what's in there... Roller weight preference relies heavily on riders weight and driving style etc. and everybody's setup is different so I can't really suggest a weight for you- but I'll give it a shot lol: 5 or 5.5 or 6 gram roller weights seem to be a decent choice for a good balance between Launch RPM and cruising speed. If the weights that are in there are heavier than that it could lead to sluggish take-off. If the previous owner was considerably lighter than you- for example- he may have preferred a heavier roller weight than what you would prefer. Just throwing some ideas out there!
2001 Pre-Bug Zuma
Athena 70cc BBK
Leo Vince GP exhaust
Athena Crank
Polini clutch

Roketa AIR 90cc 2t
Adly JA90 90cc 2t ATV engine
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Modified Hoca Vari
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