Piston Identification

Jerry Doe · Jun 13, 2015

Hello Norton experts. I need some help identifying the pistons in my 750. I have measured the bores and piston skirts and a rebore is not needed. I am going to get new rings for the pistons. I want Total-Seal rings or at least Hastings rings. I am not sure what type of pistons I have. The R/H piston is stamped +10 thou and L/H is not stamped +10 thou. Could you have a look and let me know if you recognize these pistons are they Norton?
(It might be easier and better to get new and rebore to +20 over, but trying to save money where I can on this restore). Cheers

LH

RH

LH

L.A.B. · Jun 13, 2015

Jerry Doe said:
Could you have a look and let me know if you recognize these pistons are they Norton?

Yes. "AE" is Hepolite.

SteveA · Jun 13, 2015

I think they are Hepolites. (AE)

You are going to struggle to get a 0.010" over ring set.

Bore it and fit these:

http://www.ebay.co.uk/itm/NORTON-750-CO ... 1064377940

Jerry Doe · Jun 13, 2015

Yes- I expect I will have to get some 20+ and get a rebore. I used JCC with Hastings rings in my MK3 and they are good so far...

comnoz · Jun 13, 2015

Is the top of the piston flat?

I may have rings to fit. I would need to know the depth of the oil ring groove. Jim

Jerry Doe · Jun 13, 2015

Hi Jim,

Bert has some NOS 10+ so i am probably going to buy those. Stay tuned...

Cheers

pete.v · Jun 13, 2015

Jerry Doe said:
Hi Jim,

Bert has some NOS 10+ so i am probably going to buy those. Stay tuned...

Cheers

Just make sure they are "Hepolites". As Jim mentioned, the oil ring depth can vary from company to company. I cannot recall if the Hepolites are shallower or deeper so it's better to stay cohesive with manufacturers.

Anonymous · Jun 13, 2015

20 thou rings - Total Seal S7007.20
Excellent - just fitted them and bedded in.
Ta.

Rohan · Jun 13, 2015

needing said:
20 thou rings - Total Seal S7007.20
Excellent - just fitted them and bedded in.

Just fitted them to what ?

10 thou over AE Hepolites ?

pete.v · Jun 13, 2015

Rohan said:
needing said:

20 thou rings - Total Seal S7007.20
Excellent - just fitted them and bedded in.

Click to expand...

Just fitted them to what ?

10 thou over AE Hepolites ?

Apparently they are one size fits all.

Rohan · Jun 13, 2015

Regardless of ring depths or widths, or piston oversizes ??

pete.v · Jun 13, 2015

Rohan said:
Regardless of ring depths or widths, or piston oversizes ??

I just went to JS's web site and there seems to be no options.

Rohan · Jun 13, 2015

P.S. Jerry, you appear to have 2 different pistons.
Have you weighed them to see that they are similar.

If not, this would not be the best, from an engine smoothness point of view ?

And, one of those pistons has a Norton part number thereon. 063358
This can be looked up....

Are these the slotted type - that the heads can pull off ??
Or the later type, that fixed this...

SteveA · Jun 14, 2015

Rohan said:
P.S. Jerry, you appear to have 2 different pistons.
Have you weighed them to see that they are similar.

If not, this would not be the best, from an engine smoothness point of view ?

And, one of those pistons has a Norton part number thereon. 063358
This can be looked up....

Are these the slotted type - that the heads can pull off ??

If you look closely you will see the other has the nuber 063359 stamped on it......left and right are different of course so it seems they are a pair.

As for the slot, you can see from the picture that it is not cut through the skirt all the way around under oil ring, so ...... no.

Jerry Doe · Jun 14, 2015

One of the pistons is 2 grams heavier than the other. They do have the slots in, but not all the way around.

I think based upon this info I will get 2 JCC with Hastings rings (+20 and rebore) like I did in my MK3. They seem very well made and performance is very good. Unless of course anyone has any cheap Venolia forged pistons at +20 they want to sell.

Thanks for helping me with this. A decision has been made!

Jerry

Rohan · Jun 14, 2015

SteveA said:
As for the slot, you can see from the picture that it is not cut through the skirt all the way around under oil ring, so ...... no.

I know we are done and dusted here, but can you from this pic ?
The slot was only front and back ?, so seeing the side view here doesn't tell much (?).

SteveA · Jun 15, 2015

Rohan said:
SteveA said:

As for the slot, you can see from the picture that it is not cut through the skirt all the way around under oil ring, so ...... no.

Click to expand...

I know we are done and dusted here, but can you from this pic ?
The slot was only front and back ?, so seeing the side view here doesn't tell much (?).

Study those first pics of the internal part of the pistons again, you really can.....look at the section between the casting marks that run top to bottom under the skirts, 90 degrees from the piston pin bosses. The effect of the 'cut is that the cast 'holes' are joined meaning that the piston crowns are only physically joined to the pistone lower section just above the piston pin bosses.

Try scolling down this and looking at the comparison pics.....though they aren't very clear,

hepolite-pistons-t12184-15.html

Rohan · Jun 15, 2015

SteveA said:
though they aren't very clear,

Amen.

Nice clear pics of slotted pistons show slots, not surprisingly.

Piston Identification

Jerry Doe

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