Crankshaft balance
- Thread starter BERT
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Time Warp
.......back to the 70's.
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The 750 nut and bolt is 5 grams lighter (30 grams) than the stud and two nuts (35 grams) so probably not a lot in it.
1̶9̶0̶ ̶g̶r̶a̶m̶s̶ ̶v̶e̶r̶s̶e̶s̶ ̶1̶8̶0̶ ̶g̶r̶a̶m̶s̶.̶
The balance hole number seems to vary so the balance from the factory might have been a little hit and miss anyway.
Edit.
That math is off.
6 x 35 grams (studs/nuts) = 210 grams.
4 bolts/nuts and two studs/nuts = 190 grams.
20 grams ?
1̶9̶0̶ ̶g̶r̶a̶m̶s̶ ̶v̶e̶r̶s̶e̶s̶ ̶1̶8̶0̶ ̶g̶r̶a̶m̶s̶.̶
The balance hole number seems to vary so the balance from the factory might have been a little hit and miss anyway.
Edit.
That math is off.
6 x 35 grams (studs/nuts) = 210 grams.
4 bolts/nuts and two studs/nuts = 190 grams.
20 grams ?
Last edited:
BERT
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Thanks for your input Timewarp.
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The balance factor affects the revs at which vibration occurs. I use a balance factor of 72 % and my motor is smooth at 7,000 RPM. I achieve that factor by filling the hole in the Commando crank with a threaded steel plug which probably weighs about 500 gram. The standard Commando crank is probably balanced at 54 %, to be smooth at about 3000 RPM. The mass of the crank is so high, that I don't think you would feel the difference when you add a couple of extra bolts. In any case, the isolastic mounts are probably over-kill
BERT
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Thanks for the explanation. I have seen the balance factor discussed in previous threads, but never really understood what it was all about. It is interesting how the counterweight can be manipulated to a predetermined sweet spot. Your explanation quantified things for me. Probably no need to worry about a teaspoon of sludge in the trap either.
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