How do you?

[Steve]

According to CSM you are wasting your time balancing the fan.
The motor itself is not 100% balanced becuase they can't get a big enough weight in the crank case to balance the piston, and of course that counterblance introduces a smaller side to side off balance in exchange for an up and down off balance (the counter rotating balance shaft fitted to big single motorcycles is to get round that).
CSM recommend putting the magnet on the cylinder head side of the fan while the motor is at bottom dead centre (piston fully down) so it is on the same side as the crank counterweight. This makes the motor/fan assembly more balanced than if the fan was exactly balanced.
This is what I did. It seems to run smooth.

Sorry, if that's the case, then why do CSM sell a balancing weight?

[robgt]

For those who disagree?

LOL
Cheers,
Rob

[moyesboy]

From the revlock FAQ on CSM's site.
Q. When I fit the magnet to the fan should I also fit a counter weight?

A. Although we make and sell counter weights for RevLock we don't often use them in-house and here's why. The weight added to the fan by fitting the magnet is about 150mg. The imbalance this causes is typically less than 5% of the out-of-balance of the single cylinder engine it's attached to so its effect will be slight. In fact most engines are less than optimally balanced anyway. There is not enough room in the crankcase unless a high density tungsten balance weight is employed which is unusual. If you bolt the fan on so that with the piston at top dead centre the magnet is furthest from the cylinder head the magnet will slightly increase the counter weight effect and may even improve the overall balance. If it's not possible to bolt up the fan like this or the fan is already drilled for a counterweight then its probably right to fit one.

From what I have read and heard, I think Colin Mill is fairly high up my list of those in the RC trade who know what they are talking about. Unfortunately its not a very long list...

[SRH990]

CSM sell a balancing weight because people want to throw their money away buying things they don't need

[Janek]

Yes, but not the other way round, the the revlock doesnt care wether it sees a north pole or a south pole, but the GV-1 does, as do a few others.

Dont forget to make a counter weight to balance it, I made mine out of a similar diameter piece of steel rod, then glued it on the opposite side, then fine balanced by shaving bits of plastic arround the edge of the fan until it was balanced on the prop balancer.

A magnet always has a North and South pole. . . . . . therefore if it doesn't work on one side, it WILL work on the other. The GV1 has a nice function that allows you to test which side works

As for a counter weight. . . . . a tad over the top for most low end heli's. . . . and its even debatable on the high end machines. . . . . the magnets are pretty light

[Rotorhead]

Its complete rubbish to say dont bother, after I fitted the magnet to my evo 50, the fuel was foaming, but balancing cured it.