I know this has been gone over before, but a search through this site and the 'net as a whole has shown up a lot of conflicting information. I have seen somewhere that singles left the Norton factory balanced to 50%, Mike Pemberton's website suggests a factor of between 65 and 70 depending on the âstate of tuningâ.
I have checked the balance factor on my 1950 ES2 tonight and have a factor of about 52%. If aiming for 50 I would be happy to leave it at that. But I am interested to hear what people on here have balanced their engines to and what the results are like? Has anybody used the same bike with two different balance factors, and if so what was the difference?
I went through a crank bal…
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Thanks for that Ian. I pho…
Thanks for that Ian. I phoned up Mike Pemberton and had a chat with him about it and settled on a factor of 66%. I have done this today so I guess we will see what the results are like when the bike is on the road.
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I went through a crank balancing exercise on my 19S a while back. With the original piston (concave top) the balance factor was 51%. I then fitted a modified Big 4 piston (higher compression) which was significantly heavier and gave a balance factor around 47%. It does not sound like a big difference but the vibration was horrendous, I don't know what it was doing to the bike but it gave me blurred vision. There were other problems with that rebuild so another rebore was required and a flat-topped Matchless piston went in, heavier than the original but lighter than the Big 4. This time the crank was balanced to 63% (had been aiming for 65%). The vibration is acceptable but I am not convinced that it is any smoother than the original 51% in the rev range that I use. If I was doing another rebuild I would not rebalance the crank unless the replacement piston was significantly heavier than the original, and then remove just enough weight from the flywheels to restore the original balance factor.
Ian McD