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Re: Crankshaft balancing

Ron, is that +40 piston an old original or a modern replacement ? Some of the modern ones seem to be very heavy,with very thick crowns.They also often have very heavy gudgeon pins.The Australian JP piston in my AJS had quite a bit of material milled out from inside the crown to get the weight down,and the pin I think we taper bored as it was so thick in the wall.

Re: Crankshaft balancing

Yes Jon it's a modern Royal Enfield Bullet piston and comparing it with one of Jan's standard bore flat top originals, it's at least 3 ounces heavier. It's with 'Ainsley' now for him to check and weigh and and let me know what he intends to do. I have every faith in Ainsley, He's well known here and apart from the mundane stuff, he builds racing and speedway engines. Ron

email (option): ronpier@talk21.com

Re: Crankshaft balancing

Ron, we are the lucky ones having someone we can trust... I have a good friend who builds allsorts of race engines,including "Mountain Motors".(14 litre v8 drag racing engines)
The point is he looks at every component for all the right reasons,no matter how basic the engine is he is working on.That piston you are using is probably very much a compromise,without weakening it too much it can likely have a fair amount of material removed from inside the crown - Anything your chap can do here will help.
Me and my riding mates often chat about the opportunities we now have to build engines to run sweeter,cooler,more power and last longer etc,than when they had to be almost thrown together to do a job.

Re: Crankshaft balancing

I collected my crankshaft from Ainsley today. The outcome is that when he first checked it, he calculated the balance factor at 43%. After drilling the flywheels at the big end area, he's achieved a balance factor of 58%.

My 'RAF' crankcases arrive from the Netherlands yesterday and I've fitted the new main bearings and ordered new gaskets and small parts from Hitchcock's, so I can proceed with the engine build tomorrow. Ron

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email (option): ronpier@talk21.com

Re: Crankshaft balancing

I've rebuilt my engine into the RAF crankcase and done 2 x 7 mile test runs on Monday and the vibration is vastly reduced. I'm planning another approx 30 mile run in the morning to watch Gedd try and straighten Tim's Indian Chief forks in his frame straighten jig after he ran into a car a few week ago. Ron
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email (option): ronpier@talk21.com

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