G3C Exhaust

Information relating to the Matchless G3 or AJS Model 16 350cc Heavyweight
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Peter Morris
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G3C Exhaust

Post by Peter Morris »

Hi All,

I have been collecting all the parts I knew I had to get to rebuild my 1959 G3C so that the rebuild would not mean the bike was a pile of bits for too long. So here goes with the first of a LOT of questions that are going to be on here.

I have just started dismantling it and thought it wise to try the new exhaust on the bike in case the brackets, one of which is welded on, need changing before blasting and stoving. Just as well because, you've guessed it, it does not fit.

The bike has been fitted with a (believed 1962) short stroke engine with alloy barrel. The engine number 16 41588 is obviously an Ajay roadster bottom end...or at least crankcases. The bike has a high level exhaust system.

I bought an exhaust pipe for it that was made up by Steve at the excellent Progressive Classic Products, but highly likely forgot to mention to him that it was a short stroke engine.

The new exhaust is 1 1/2" external diameter, so is the old one, but if you look carefully you will see that the Cylinder head end has
had a piece of 1 5/8" pipe welded on so that it fits the 1 5/8" exhaust port. I have looked on the net and all I can see is pipes that are 1 1/2" or 1 3/4" with no mention of a 1 5/8" pipe .... or at least the end of the pipe.... and no mention of a 1 5/8" cylinder head.

I don't know anything about the engine yet as I have never had it apart, but it obviously is not a standard road nor comp engine.

Right, has anyone heard of a 1 5/8" exhaust port or has mine been enlarged?
Does anyone know of a company that can supply 1 5/8" ended, 1 1/2" exhaust pipe, or do I need to get a piece welded on the end of mine?

Any help would be greatly appreciated.

Peter
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Peter Morris
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Re: G3C Exhaust

Post by Peter Morris »

P.S. This is what the head is like
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dave16mct
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Re: G3C Exhaust

Post by dave16mct »

The 62-on short stroke road models had 1 5/8" exhausts, so I suppose the comp models were also 1 5/8".
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Peter Morris
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Re: G3C Exhaust

Post by Peter Morris »

Thanks Dave,

I guess it's get a bit of 1 5/8" welded on then, and into the pile for the chromers.

I wouldn't imagine the lack of the extra 1/8" will make any difference, but I suppose AMC didn't increase the size for nothing.

Peter
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