Help! My beloved '66 G3 - p*ssed n' broke :-(

[fishsponge]

As you may have guessed from the title of this topic, I have a bit of a problem... My original 72mm 1966 350 single Matchless G3, short-stroke piston has a crack in it, and I need a new one

Here's what happened...

The bike has been burning oil for some time now, so a good friend and I took a look at the piston rings, among other things, and discovered that they were basically useless.

This lead me to another good friend's (Rick Edwards') place where I employed his truly amazing piston ring knowledge (and collection) to obtain a new set of rings for my piston (thanks, Rick! ).

Upon inserting the new rings into the cleaned piston, we discovered that the oil control ring wasn't rotating as freely as we would like, so we took them off again to examine the groove a little closer.

It was then that my friend discovered that this "scratch" was actually a crack that ran across all three piston ring grooves, and into the bottom of the crown.

The piston is therefore useless.

So... I have a dilemma - there are 5 weeks until my first club run, which is then the beginning of a jam-packed summer full of steam rallies, bike shows, club runs, the Matchless/AJS Owners Club jampot rally 30 minutes from my house(!) etc... and I need a new piston!

So, if anyone has one, knows of one, knows of someone else who has one, or anything at all that might get me a new piston, please get in touch!

I plan on putting some adverts in other places on the web too, and another good friend is going to place an advert in a few magazines for me too.

Thanks in advance, people... there has to be one out there somewhere... there just has to be!

[guest288]

http://cgi.ebay.co.uk/MATCHLESS-G3-AJS16-GENUINE-NEW-30-HEPLEX-PISTON_W0QQitemZ270342014018QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item270342014018&_trksid=p3286.c0.m14&_trkparms=72%3A1121%7C66%3A2%7C65%3A12%7C39%3A1%7C240%3A1318


Is this one? It may be oversized.

[pigafetta]

Doh! I was just about to post that link!

The fella who's listing it seems to have a load of old Brit stuff if you check his other items. I reckon if this piston is no good to you it might be worth emailing him to see what else he's got.

Dave B

[fishsponge]

sadly, that piston is the wrong one, but thanks for the lead!

As it turns out, there may well be a brand new one(!) at AMC Classic Spares. I'm going to pay them a visit tomorrow morning to take a look... i'll keep you informed!

[guest288]

I've been searching for AJS/Matchless stuff, there are a few pistons on ebay, but there are over 1000 products so take a look and see if there are any that might be of use to you.

[fishsponge]

I've already had a browse or two on eBay actually and found nothing of use yet... I do intend to keep looking though, of course :-)

As mentioned on the AJS & Matchless Owners Club forum:

As for the piston from AMC Classic Spares... unfortunately it is the wrong one... it's 72mm etc... with the gudgeon pin in the correct place etc... but the grooves in the crown for the valves to go into are nowhere near deep enough, or wide enough, and upon examination, there doesn't appear to be enough metal underneath to mill any more out...

So basically, I'm still after one! I really don't want to turn up to my first Jampot rally by car... it wouldn't feel right.

The problem i'm having is that everyone who says they have the right piston for me actually has the wrong one... they usually have all dimensions correct except one.

The first piston was good, except it was 74mm diameter.
The second piston was good, except the valve cut-outs were the wrong size/depth.
The third piston (from a fellow Fenrunner) was a +30 and also has the wrong valve cut-outs.

I certainly hope i'm not doomed to failure... there must be an original 72mm piston for my bike out there somewhere, surely?!?!?

Anyway, i have a list of names and companies etc... to phone now, from this site, other sites and from speaking to people so I shall be busy for at least an hour or two tomorrow. I shall let you all know how I get on...

Thanks again for the help! 

[guest295]

This may seem a bit improper, but the only things that really matter with pistons are diameter, deck height and diameter of piston pin (which can easily be corrected). i once replaced the piston on an East German Simson 250 with one from a BSA 500 twin, very successfully. You might well find something out of a Toyota that's far better than the original.

[fishsponge]

thanks for the advice... i appreciate that there are only a few things that matter with pistons, but i'm far from resorting to an "alternative" solution at this stage... I'm sure i will get more and more desperate as time goes on, but for the moment, i'm still holding out some hope that i *might* either find an original, or an identical one from another bike...

And, while we're on that topic,

First of all, would a piston from a 1961 Matchless 650 fit my bike?

Secondly, what about the piston from a 1960 350cc Lightweight Matchless?

And finally, what about the piston from either a Velocette Venom 500 (with some gudgen pin adjustment) or the Velocette Viper 350? I'm told at least one of these bikes has the same stroke and bore, so they're a possibility perhaps.

Thanks again, people!

[themoudie]

Aye fishsponge,

Venom = 86mm bore Jaguar pistons work well in these!

My regards, Bill.

[themoudie]

Aye fishsponge,

I ken it's not what your after, but just for a looksee at whats about: Fleabay: 370129810971

Also this http://www.classic-motorbikes.com/stock.asp?Ref=FA31&Lang=en Again the pistons are Arias.

Finally, http://www.ariaspistons.com/custompistons.html

Toodle pip, Bill.