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M20 paint and small end bush

I wrote weeks ago about paint. I ended up having most the frame forks wheels and other parts soda blasted and powder coated in a matt finish. Very good job at a good price. Colorcote, Hethel, Norfolk. Cheaper than paint but a similar yet more durable finish.
My next subject is the small end bush. I had some circular motion when handling the piston on the con rod. Took the piston off and have found that the small end bush is turning inside the conrod and can be pushed in and out of the conrod quite easily. I read on the forum that someone else had a similar problem but not on a BSA. Any owners have the same problem and if so what is the best solution preferably without stripping the engine.

email (option): araine11@hotmail.com

Re: M20 paint and small end bush

Hi Arthur...Well if you're lucky the 'slackness' will all be material worn off the bush and fitting a new bush will solve the problem. If not, there will be wear in the conrod eye as well. In that case it will have to be carefully measured and a 1 off bush made to suit.
I like a fairly 'heavy' fit on the bush to help avoid these sort of problems so in that case the outside diameter of the bush would be .002" bigger than the size of the rod eye before fitting.
Bushes can be fitted in place and after fitting reamed to size using an adjustable hand reamer, taking SMALL incremental cuts to bring the bush to the finished size.
The gudgeon pin should be a 'easy' sliding fit but with minimal free play. When the piston is fitted with an oiled pin it should fall freely under its own weight.
If the conrod eye measures up with more than a thou or so ovality it should be replaced...Ian

email (option): ian@wright52.plus.com

Re: M20 paint and small end bush

Thanks Ian. Do you have info as to what the inside diameter of the conrod should be? Before I buy a new bush I could take measurements and see what we have. One step at a time.

email (option): araine11@hotmail.com

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