'49 G80 Piston

Samuel · Post by **Samuel** » Tue Feb 07, 2012 10:41 am

Does anyone have any leads or information on where I can find a standard or +02 piston, wire wound for a '49 G80 - needed to get me back on the road.
cheers Sam

john · Post by **john** » Tue Feb 07, 2012 12:59 pm

I nearly had a result for you as I have ’48 piston but then it dawned on me that you wanted wire wound one which has the lower gudgeon pin design. Sorry can’t help

chrisb · Post by **chrisb** » Wed Feb 08, 2012 2:25 am

Hi ,
JP Pistons in South Australia make pistons from solid stock for most AJS/Matchless. I bought mine from there, although not wire wound. Hope this helps, regards Chris

ianselva · Post by **ianselva** » Wed Feb 08, 2012 9:15 am

JP pistons are not made from solid stock ,they are made from a basic cast blank which they machine in different ways to fit different engines . That is why some pistons they supply are horrifically thick and overweight and upset the balance of your motor.
You'll find a lot of other info about them if you search the forum.

Ian

cf160 · Post by **cf160** » Thu Feb 09, 2012 4:27 am

Hey Samuel:
After a quick look I turned up one wire wound 18 piston but it has been used a little . By the way, it has the identical pin height as the non wire wound piston from the same era('46-'50) . These two pistons are identical except the wire wound one has been used and you would not likely wish to use it as it has knurling cross hash marks on the skirt and no usable rings. The non wire wound piston has not been used but has only one ring(the oil scraper). It has the pin and no circlips . It is a standard size piston (3.25") and would be my choice if I was fitting to a fresh bore. However, you can have either one if you give your word to help me find a cover for my'46 AJ Mag Chain case with the AJS logo on it.
Sincerely,
David Potter (cf160) in Ottawa, Canada

wilko · Post by **wilko** » Thu Feb 09, 2012 8:06 pm

Are you saying the wirewound one has the long conrod gudgeon height? Strange?

cf160 · Post by **cf160** » Fri Feb 10, 2012 12:00 am

Yes, Doug, I did say so, but looking again , the wire
wound piston has a greater pin height by about one millimeter. I couldn't see it before as I merely stuck the g.pin from one into the other side by side and it looked horizontal, but , you are right , there is a slight difference in pin height. I must say that I do not know the year of these pistons and one has "Helex 10197" cast into the inside skirt.
The wirewound piston has "W 117/5" , a "B"under
that and a "BHB" inside a circle. All on the crown.
This piston has a slot which runs from the bottom of the skirt to the oil ring just above the wire winding There is only one ring which is broken. It did not have a g. pin, but I can include one as I have a number which I will not use.
Dave(cf160) in Ottawa

cf160 · Post by **cf160** » Fri Feb 10, 2012 12:00 am

Apologies to all: I spelled Heplex without the "p"in my previous
post , a typo.
Dave(cf160)

Samuel · Post by **Samuel** » Fri Feb 10, 2012 10:19 am

Hi David,
Thanks for your response regarding G80 piston. Are you able to post a couple of pictures of the wire wound item together with precise dimensions ?
thanks
Sam Trenchard

john · Post by **john** » Fri Feb 10, 2012 11:00 am

The 10197 Heplit code is for a 7.2:1 piston to fit a sort conrod engine (low gudgon pin design) the equivalent of the factory wire wond piston but without wire winding.

The earlier pistons had the gudgon pin higher in the piston and I had always assumed (and I hope correctly) that the gudgon pin change and the wire wound piston design change happen at the same time.

David,

I am sorry but I think you have the wrong piston for your engine assuming that your ’46 engine is standard.