Question of balance

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G15 Roy
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Re: Question of balance

Post by G15 Roy »

I am sure that there would be no clearance to run with these attached and G9 would be a standard 500 crank and not for a CS?
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jack clegg
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Re: Question of balance

Post by jack clegg »

I wouldn't worry about piston weight. Just remove those huge magnets & it may be all OK. I am suspicious that this is a joke. Is there really enough clearance in the crankcase? Surely T&L would never have fitted them? Only an utter retard would do such a thing. TTFN Jack
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Dave T_LAPSED
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Re: Question of balance

Post by Dave T_LAPSED »

Sorry chaps, I didn't explain myself properly, I found that to balance the crank I needed to attatch the weight of the magnets. So if a G9 is not the original crank what repercussions could that have?
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dave16mct
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Re: Question of balance

Post by dave16mct »

No, the flywheel was the same as a standard G80 until the shortstrokes in '56.
Dave.
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Re: Question of balance

Post by Dave T_LAPSED »

Thanks for that Dave16, only leaves the 70gms imbalance!
Dave T_LAPSED
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Re: Question of balance

Post by Dave T_LAPSED »

Revelation! Thank you Phil Irving (Tuning for speed)
After reading, inwardly digesting and re-reading, the penny dropped, how to calculate the weights to balance the crank.
I'm sure those that have this knowlege will be thinking"what a duffer!" but I have never messed about with engine lowers so much before as I've never had a so messed about engine before!

The Hepolite piston in my engine when I bought it is 59gms light working on a balance factor of 66% I esteem that to be very much out.

I got, in amongst the obligatory boxes of "who knows what these are?" bits, a Wellworthy +20 piston which I didn't fit as the Hepolite was already in the motor! This piston is heavier! It works out to 68% balance or 15gms light at 66% so I know which one goes back in when I rebuild !

I just hope I've got it somewhere near right :roll:
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Harry44
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Re: Question of balance

Post by Harry44 »

Balancing a single or parallel twin is more art than science, cos science says you can't do it. :lol:
si is does non opportunus vos postulo a maior pango
Dave T_LAPSED
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Re: Question of balance

Post by Dave T_LAPSED »

I might be forced to agree! Good old trial and error. :?
aobp11
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Re: Question of balance

Post by aobp11 »

David, I'm not sure how you came to your balance conclusions.
I think you can't arrive there without knowing the reciprocating weight of the con rod.
Also, did you take into account that the magnets were attached at the outside while the bigend is at shorter distance from the centre? In your first messages you carried 70 g one-to-one over to the piston side I think.
Albert
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Re: Question of balance

Post by Dave T_LAPSED »

Quite right aobp, I must forget the magnets! I followed Phil Irving's formula which entails taking 66% of the weight of the piston, pin, rings and clips plus the weight of the little end of the con rod.Then subtracting the little end weight and the result needs to balance suspended from the little end with the crank allowed to turn on rails! Phew! It took me a long time to arrive there but my heavier piston balances to within 15gms. I'm prepared to give that a go, the other piston was 59gms out!
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