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Post by baldmeister on Apr 15, 2013 16:48:08 GMT
hi all , whats the advantage of a lightened flywheel on a px vespa ??
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Post by sbwnik on Apr 15, 2013 19:39:09 GMT
It'll take off a lot quicker and possibly try to stand on its back wheel.
It'll also not climb hills, struggle to tick over, and - if the engine has been played with - quite possibly twist the crank.
Like anything else though, it's something to do once you've done all the rest of the engine work.... Always start with a cylinder kit and porting, and work your way outwards from there.
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Post by kru251 on Apr 15, 2013 22:31:05 GMT
As Nik says, quicker engine 'spin-up' due to less rotating mass, but part of the flywheels effect is to get the engine to spinning over at a fairly constant speed (depending on throttle setting of course) without the firing effects of the engine making it speed up slow down, speed up, slow down. That means a faster tick-over to avoid the power pulses. A lot less civilised to ride and more stress on the crankshaft due to this on/off/on/off power effect.
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Post by sime66 on Apr 16, 2013 6:12:34 GMT
Think I'll give that tweak a miss
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Post by kru251 on Apr 16, 2013 7:31:24 GMT
Well I always see that the manufacturers spend thousands of whatevers, be it Francs as it was or Euros, on development so why wouldn't they optimise production and reliability to get less warranty claims and a poor reliability record. We can improve things a bit with gas flows and larger bores or stroke, but you can bet the increase in power comes at a reliability/expense cost.
When I raced powerboats I had a saying. The last 10% of power (increase) comes at 90% grief. Unfortunately it seemed to be true!
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Post by sbwnik on Apr 16, 2013 18:26:37 GMT
You could lighten the clutch to offset the twisting though. I only know one person who's actually done it though, and he's a bit eccentric.
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