Crankshaft

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pin
Posts: 254
Joined: Sun Oct 16, 2011 3:43 pm
Location: greenford middx

Crankshaft

Post by pin »

Hi all
Has anyone had the crankshaft lighten and balanced like Chris Applebee and did it make any difference
Thanks
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Pin
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: Crankshaft

Post by Alan H »

Chris Applebee balanced my 750 crank and it made no difference at all. Waste of time & money.
Proof that four strokes are over complicated
teazer
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Joined: Mon Mar 07, 2011 8:10 pm
Location: Chicago

Re: Crankshaft

Post by teazer »

I would expect the pork chop effect would potentially improve performance if the motor was fitted with reed valves and a really good exhaust system, but on a stock motor, I would be very surprised if it made much difference.

The idea behind a light crank is that there's less inertia and that allows the crank to accelerate faster, but when the rest of the bike weighs as much as a pocket battleship, the difference will be tiny. IIRC, Barry Sheene tried lighter cranks in his XR11 (TR750) and went back to the heavy crank on fast tracks like Daytona.
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canaletto5
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Re: Crankshaft

Post by canaletto5 »

pin wrote: Mon Apr 26, 2021 8:52 pm Hi all
Has anyone had the crankshaft lighten and balanced like Chris Applebee and did it make any difference
Thanks
.
.
.
Pin
Yep, lightened my wallet very well
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pin
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Joined: Sun Oct 16, 2011 3:43 pm
Location: greenford middx

Re: Crankshaft

Post by pin »

That made me laugh
Think I will go with Barry Sheene it worked for him
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Pin
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pin
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Joined: Sun Oct 16, 2011 3:43 pm
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Re: Crankshaft

Post by pin »

Hi
The bike I have is a 750a does all the cranks fit all years
I’m thinking of buying one to get it rebuilt to swop over later
Thanks
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Pin
Kettletimes3
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Location: Sunny Wales

Re: Crankshaft

Post by Kettletimes3 »

Anything from L on will work.
teazer
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Location: Chicago

Re: Crankshaft

Post by teazer »

That's a great plan. And if there's rust or other damage that needs to be treated, the bike isn't spread all over the shop.

You could use a J or K crank and leave out the thrust washers inside the later style pistons, but L on cranks are better.

When the design changed, rods and crankwheels changed as well as the center seal. I have seen a couple of cranks with a mix of early and late parts and they came from bikes that didn't make it, so I'd stick with a 74 on crank.
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pin
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Joined: Sun Oct 16, 2011 3:43 pm
Location: greenford middx

Re: Crankshaft

Post by pin »

Hi
Has anyone got a crankshaft I can buy
Thanks
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pin
Posts: 254
Joined: Sun Oct 16, 2011 3:43 pm
Location: greenford middx

Re: Crankshaft

Post by pin »

Don’t know if this could be the problem with the vibration I’m getting at about 3500 rpm,
Only look at one side but the exhaust hanger is in a sorry state,
Are they a easy job to do,
Thanks
Pin
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