Barrels and Pistons

[Krill]

Hi, just pulled the barrels off my 82 R65 and they don't look too good, as far as I can make out the should be Nikasil but the liners are magnetic so how do you tell if they are plated or not? the markings are-----
Left Barrel
US  Mhale  82 ZN3W1

Right Barrel
i9     Mahle    82ZN5W2

Left piston
81.96

Right piston
92   +   81.97     B

Any info or help would be much appreciated

[Barry]

Don't see how a Nikasil barrel could be magnetic as the coating is direct on the alloy surface.  Unless the coating itself is magnetic otherwise it sounds like you have the earlier sleeved barrels.

In what way do they not look good ?


According to the piston sizes the barrels have not been re-bored.  The pistons are not a matched pair as the left is a size A and the right is a B. Don't think that should be an issue though. The + is a weight mark rather than a size indicator and there should ideally be a + mark on the left piston as well.

The barrel designations I don't really understand except that the right barrel size should be 82.005mm and you can see 82 and 5 in the designation.

That doesn't hold up for the left barrel as the correct bore size for an A piston is 81.995mm

[tvrla]

Sounds like something happened to the original nikasils and were replaced with earlier cast iron barrels. The nikasils aren't magnetic. And you should see the difference in material looking at the head sealing surface where the liner ends and the outer aluminum cooling section begins.

[Krill]

Thanks for the help, the cylinders are the older cast iron type and are showing quite a bit of wear so guess I will have them rebored, as one piston is stamped B does this mean it is the first rebore size, if soI will I have to get C size pistons and last question, where is the best place to buy pistons? they seem very expensive on the main sites, I bought a pair for a Norton last year for less than half the quotes I've had for BM ??
Thanks again
Chris

[Barry]

as one piston is stamped B does this mean it is the first rebore size

No, there are A,B and C grade sizes within the standard bore size and within each rebore size.  The idea is to bore the cylinders, measure them and apply a grade for the purpose of selecting the correct grade of piston.

The fact that you have one A piston and one B piston was just another clue that the cylinders were not original as the factory cylinders would normally have been a matched pair of A's B's or C's  


RH column is R65 centre column R45

[Krill]

Thanks for that Barry

[tvrla]

Rather than going the route of boring/new pistons, find a low mile set of nikasils with matching pistons. They show up frequently. I know of a couple sets right now for around $150. The nikasils tend to last a couple hundred thousand miles, so you'd be way ahead finding some with 30K and be done with it.