I am going to re-assemble my crankshaft this weekend and was wondering if people have experimented with balance factors in the past and if so what sorta numbers do you reckon? I think between 60-65 is about normal for singles but was wondering what people reckon? Its a 1936 inter im doing but it has a manx crank and big end in it. I wont be racing it so am looking for smoother (yeah right!!) low speed running.
Andy, hopefully someone mo…
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Previously wrote: I am goi…
Previously wrote:
I am going to re-assemble my crankshaft this weekend and was wondering if people have experimented with balance factors in the past and if so what sorta numbers do you reckon? I think between 60-65 is about normal for singles but was wondering what people reckon? Its a 1936 inter im doing but it has a manx crank and big end in it. I wont be racing it so am looking for smoother (yeah right!!) low speed running.
Andy- I balanced my 1950 ES 2 crank at 66 % as recommended by Mike Pemberton and also Phil Irving in his tuning book- It runs beautifully at 50- 55 mph. I do not know what rpm this is as I have no tach but I am very happy with it-Hope this helps-Richard
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Thanks for the info. I ha…
Thanks for the info.
I have had a play with it thisevening and currently only seem to have a factor of 41%. I guess I have some holes to drill!!
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I'm confused - what makes…
I'm confused - what makes you think Norton got it wrong when they built your engine?
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Nothing. But I have fitted…
Nothing. But I have fitted a new piston which despit being as close as I could get to the origonal, it weighs more. Hence the need to rebalance the assembly.
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Hi Andy, A while back I fi…
Hi Andy,
A while back I fitted a Big 4 piston to my 19S. This isabout 60gheavier than the original piston and gave a balance factor of 47% (original was 51%). Vibration was intolerable. Since thenthe piston was swappedfor a Matchless item and the crank rebalanced to 64% (my target was 65%). I am not convinced that it is noticeably smoother than Norton's original balance - but it could be that I am riding too slow! My '37 CS1 engine is in pieces at the moment so if I get time I will check the balance factor for that - vibration on that bike is very acceptable.
Cheers, Ian McD
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Andy,
hopefully someone more knowledgeable chimes in, but i have been told that all Norton Singles left the factory balanced to 50% (i don't know whether that should have been qualified as all roadgoing Norton singles?). It seems that BSA used 58% for their singles and i have seen comments on another forum about 60% or higher working better for Nortons at modern road speeds, so it sounds like you are on the right track.
best of luck
Iain.