MOPED ARMY

Lol.

anyone get any miles on these yet? i want a lightened bell for my 50cc bike, less rotating mass = good.

^Some people think this. I don't think it's accurate.

i lol'd a little.

The reason that a Hobbit's crank shaft can support two very different weights on it is because one side of the crank shaft is much longer than the other. The weight is still balanced but it is balanced in a different way. Not the case on an e-50 crank because it is almost the same length on either side.

The vespa cranks are different because the little nub part on the opposite side of the crank is supporting all of the weight of the variator while keeping the actual crank straight.

What should be done when lightening the rotational mass of any two sided crank is find the stock weights of each side and establish the correct ratio between them. Then keep that ratio when reducing mass.

But what do I know.

http://www.ux1.eiu.edu/~cfadd/1150/09Rot/RotDyn.html

http://www.xyobalancer.com/_blog/XYO_Balancer_Blog/post/Vibration_in_Rotating_Equipment/ (edited)

I have one... I've been running it for over a year. It's awesome. Plus, you can see into your engine without taking the clutch bell out.

End of story.

The closer a weight on a rotational axis is to the origin of rotation the less rotational mass it possesses. In order to compensate for greater standing mass you need to move the more massive object closer to the origin or rotation. This allows the two separate pieces of different masses to have the same rotational mass, keeping the axis of rotation constant.

Otherwise the object with greater rotational mass will exert greater centrifugal force and offset the axis. Leading to vibration which will cause damage to the bearings, seals and eventually warp the case.

No it it won't kill a stock bike to lighten the clutch a bit, but when you are make extreme modifications such as the ones that Ben is working it should at least be taken it in to account.

Moped motors are not designed to withstand the stress that is put on them by heavy modification and with that in mind any serious builder should/would do anything they can to make all of their modifications as sound as possible.

I'm not trying to be a dick, but I know a lot more about physics than most. Being that mechanical engineering is 90% physics I think I have a decent grasp on what I am talking about.

What it seems like you are getting at is the moment of inertia and radius of gyration of the two masses. Again, it is not a problem because each mass is itself balanced along the axis of revolution. Assuming the flywheel and the clutch's center of mass is exactly the center/where they bolt onto the crank, there is no way for vibration to be introduced.

If you tried to take the crank and spin it like a baton, then yes you'd have problems.

The imbalance that you see between the two masses is not affected by the crank's rotation. It's likely that because of one side being heavier, one of the two crank bearings will see a little more downward force. But that depends on the placement of the two bearings anyways.

I've run these on every possible setup I can imagine and I've never had a problem. With inertial difference's on inverse/transverse rotating mass calculations. I'm not sayin' your wrong, I'm just sayin'. if the mass wasn't balanced radially I could see that being problematic.

you can get them here when they are not sold out.

And I don't need to discuss my qualifications I made these, burthed um with my own 2 hands,

If I could just add... flywheel's being as heavy as they are works to act as a sponge, soaking up vibrations caused by natural (factory) imbalances in the engine... but people put HPI's on their ped all the time. An HPI is a LOT lighter than a stock magneto... these clutches/bells are lighter than stock by a matter of grams. So if anything, post about imbalances in a thread about HPI.

Hahah I should have expected it. Right as I finish putting a bunch of work into adapting a clutch for my next build, this thing pops up. Looks like maybe I'll have to pony up the cash and drop it in my current one.

I predict a retail price of 175-250. Sound about right?

@Max

Would you spend 200 on a kit?

on a CDI?

on a pipe?

200$ for a clutch that is like a KTM or even a BRN, fully tuneable and a true "drop in/bolt on" is cheap.

And we dont even know what they are going to charge for it yet, or even if it holds up, or spins on the crank at high engagements or strips the threads of the centers out.

Calm for a second and let them research and get a mass production going, then you can bitch about a fictional price.

Personally, I have spent over 1K in developing MY OWN clutch. Not for mass production. Its expensive dude, as you are well aware of. It takes time and R&D to get you to where you are today and if you dont make 1000 of them its gonna be super spendy.

I'm predicting around $89 for this clutch, but could be wrong.

The biggest question for me is made in the USA or not.

I've had custom bike frames manufactured in Taiwan and shipped over. If 77 went that route I'd imagine it'd be under $100 retail. I bet after R&D is complete actual manufacturing would hover in the $30-$50 range cost.

However R&D and modeling costs a BOATLOAD. Not to mention minimum orders of probably 500 pieces, 3 month slowboat shipping, Quality Control, etc etc etc.

If they're being manufactured in the good ole USA I'd say they'll be about double that. But hell ya for making an AMERICAN product.