short stroke piston

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
moley
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short stroke piston

Post by moley »

Hi all , a mate is in search of a piston 350 short stroke 1962, are they as hard to find as I am told ? Can any conversion be dne using another piston ? Che4ers andy
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ajscomboman
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Re: short stroke piston

Post by ajscomboman »

More chance of finding a Unicorn horn. Try contacting Ken De Groome to see if he knows of a suitable replacement. I've had 2 56 short stroke motors done by him and the 350 now uses a converted 650 flat top piston as the original 72 mm ones are unobtainable. I'm sure he'll know of a substitute for the 74mm type.

Ken's details are in the back of the Jampot in the trade ads.
G15 Roy
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Re: short stroke piston

Post by G15 Roy »

Why don't we get some made.
Roy
McMaz
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Re: short stroke piston

Post by McMaz »

G15 Roy wrote:Why don't we get some made.
Roy, I would put my name down for one. Is there enough interest to justify the upfront costs?
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Les Howard
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Re: short stroke piston

Post by Les Howard »

A good idea, as well as the 350 piston I'm sure the late short stroke 500 bike owners would also like a batch of pistons available....HOWEVER....the piston needs to be fit for purpose...not one that simply fits!!!....By that, I mean have the correct tapered gudgeon (wrist) pin and have a similar weight to the original....not a slug of lead like JP piston are...I would recommend contacting : Omega/Accralite pistons they are very helpful and I'm sure could come up with a good piston.....Les

http://www.omegapistons.com/aboutaccralite.php
Last edited by Les Howard on Fri Dec 18, 2015 6:19 pm, edited 1 time in total.
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ajscomboman
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Re: short stroke piston

Post by ajscomboman »

Before anything can be done, a suitable standard size sample would have to be supplied to us. Then and only then! would the parts service consider the proposal.
Please bear in mind, small batch manufacturing + low demand = high unit cost
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clive
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Re: short stroke piston

Post by clive »

We have been looking into this recently as a member of West London needed new rings for a 350 shortstroke. We seem to have established that the rings supplied with the current club twin 600/650 pistons will fit the original 350 pistons as fitted by AMC. They are thiner that the longstroke rings. If the club was making pistons they would presumably need to make at least +20 to +60 (ignoring standard as few people would be seeking them and anyone resleeving would have to fit a +20). So thats 3 pistons for the 350 shortstroke or were there different designs (position of gudgeon pin, shape of piston crown etc) in different years? If the 500 piston was also made thats at least 6 pistons to be manufactured, sounds very high unit cost to me.
clive
if it ain't broke don't fix
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ajscomboman
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Re: short stroke piston

Post by ajscomboman »

Different piston Clive. When I spoke to you at Kempton I mentioned the 600/650 piston rings would fit the earlier 350 short stroke with modification as they're 72mm. You can also modify a flat top 60 on high comp piston to fit the 350cc and rebush the small end to suit the gudgeon pin. However the later 350 short stroke is 74mm.
G15 Roy
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Re: short stroke piston

Post by G15 Roy »

So if we are going to look at this we will need a sample/samples any one got them?
Roy
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ajscomboman
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Re: short stroke piston

Post by ajscomboman »

Let's hope it doesn't turn out like the L/W clutch centres, plenty wanted one and so we commissioned them only for them to run away when they turned up and the price was quoted. Out of 50 only 8 have sold in 2+ yrs.
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