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ES2 Piston

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ES2 Piston

Posted by glenn_collins at April 30. 2010

I have recently taken the top end of my 1949 ES2 apart for a de coke and think that I may need a new piston or at least new rings. The bike is showing 30K on the clock but want to know if the piston is original size or over size the number stamped on the top is 796/03 OT. Can anyone help please?What would the measurements be of bore to require a re-bore? Cheers Glenn. PS Russell Motors in Battersea were not very helpful - he told me on wed to call back on Fri when he'd have his catalogues & when I did he accused me of not having a clue and to take barrel and piston to re bore shop! shall not be using them again.

Re: ES2 Piston

Posted by Ian MacDougall at May 01. 2010

Russell advice is not so bad. A good rebore guy will have the tools and experience to measure your piston & bore and tell you whether you need a rebore or not. You are going to need a rebore guy at some point anyway. Talk to people (NOC, VMCC, VJMC etc) in your area for recommendations concerning rebore shop with a good reputation.

You probably don't want to fall out with Russell Motors - their business is supplying parts that they stock and you need!

Cheers, Ian McD 

Re: ES2 Piston

Posted by glenn_collins at May 02. 2010

cheers for advise Ian. You're right perhaps Russell Motors bloke was just a bit stressed out when I called. The thing is all I wanted to know was whether that piston number was the original one or an oversize - I would have thought not too difficult to determine? regards Glenn.

Re: ES2 Piston

Posted by ron_corbin at May 02. 2010

Hi

Measuring bore size does require specialised gauges but it seems that would like to know if you need a rebore? as much as the actual size.

The piston top ring rarely comes right to the top of the cylinder bore, usually you will find a ridge of carbon around the top of the bore at this point, move the piston down, place a rag in the bore and gently remove this ridge.

You now have the size of unworn bore, with tip of finger feel for a wear line around the top of the bore, if the bore is badly worn there will be a noticeable difference between what is known as the thrust side of the bore and the rest. If the ware line is even with no real step, and the general condition of bore looks good i.e. no scoring; it should be OK simple easy check you can do this weekend and you may avoid the slippery slope to a complete engine rebuild.

Ron.

Re: ES2 Piston

Posted by anna jeannette Dixon at May 14. 2010

Previously wrote:

I have recently taken the top end of my 1949 ES2 apart for a de coke and think that I may need a new piston or at least new rings. The bike is showing 30K on the clock but want to know if the piston is original size or over size the number stamped on the top is 796/03 OT. Can anyone help please?What would the measurements be of bore to require a re-bore? Cheers Glenn. PS Russell Motors in Battersea were not very helpful - he told me on wed to call back on Fri when he'd have his catalogues & when I did he accused me of not having a clue and to take barrel and piston to re bore shop! shall not be using them again.

hello get in touch with Mike Pemberton 01257 471014

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