'49 G80 Piston

Lance · Post by **Lance** » Wed Jun 27, 2012 9:37 pm

Peter,

As ITMA has stated, 9991 is not correct for your year. If looking for a Hepolite replacement, the number you want is 10197.

Regards,
Lance

cf160 · Post by **cf160** » Wed Jun 27, 2012 10:14 pm

But Lance:
Is there any difference between these two beyond
the weight? Are the pin height and skirt length not
exactly the same?
Dave

itma · Post by **itma** » Wed Jun 27, 2012 11:29 pm

these are 350 but the difference is the same
http://www.ajs-matchless.com/pic_display.asp?id=1274

cf160 · Post by **cf160** » Thu Jun 28, 2012 12:26 am

So I must use the 9991 for my '46 crank with the
long rod. The 10197 will stick out of the bore 3/4"
Why all the changes year to year?

Peter Lecompte · Post by **Peter Lecompte** » Thu Jun 28, 2012 12:35 am

Hi Lance, I remember reading another post on this subject and you were involved. Did you ever find a Hepolite/Heplex part No. 10187 0.020" piston? Or should I just realise and accept that they are not available and purchase a JP (or other brand) off the shelf? Ken, I can see the difference now. @#$%^ and frustration. Back to the start. Cheers Peter

Peter Lecompte · Post by **Peter Lecompte** » Thu Jun 28, 2012 12:41 am

Hi, typo in my last post. I meant 10197. Good question David about the changes in the connecting rod length? Do you now have a spare 10197? Cheers Peter

wilko · Post by **wilko** » Thu Jun 28, 2012 2:17 am

Most manufacturers copied each other i think. Bsa went to a shorter rod as well.

cf160 · Post by **cf160** » Thu Jun 28, 2012 2:46 am

Well .Peter , I guess I might since I am thinking my rods are all the longer ones. I will have to measure to be absolutely certain, but it looks like
I do. Even the 350 is a long stroke. I have only two single engines (500s) which have any chance
of smelling gasoline again. I have only one good
big end and that is on the long rod crank , So, It is
rather likely that the 10197 piston is not for me.
It is rather new looking , but It may be in a larger oversize than you wish. I believe it is .050"
over. Just digging them out, it is not .050" but .040" oversize, It has a fairly thick skirt, rings and pin is there and no scratches on the skirt although a little dirt on top and here and there.
I do not think it has ever been fitted to a bore.
It weighs 549 grams with pin and rings.
I think I got it from that Malaysian guy on
Ebay Marked "Heplex 10197" you can have it for what I paid plus shipping. I don't recall it was so very much . The shipping was almost as much or a good part of it.

Peter Lecompte · Post by **Peter Lecompte** » Thu Jun 28, 2012 3:48 am

Hi David, sent you a PM. Just confirmed the connecting rod to be 6 7/8" between centres. So a short conn rod and a 10197 piston is the combination I now seek. Thanks Peter

itma · Post by **itma** » Thu Jun 28, 2012 9:47 am

the length of the conrod in this case does not affect the stroke.
short conrod is not a short stroke engine