Finished taking the cylinder off of my new bike to install a fresh top end and I noticed that the gasket surface of the front cylinder was really bad. It looked like someone peened the surface in a bunch of different places. There were at least 5 different groups of little dimples on the surface. I assumed that it wouldn't seal probably but I put it together anyway. I leak tested it and of course it wasn't sealing so I took it back apart.

I tried lapping it but it wasn't getting anywhere near getting them out so I took the cylinder to someone local that was recommended. He cleaned up the surface and mentioned that he had to go down about .004" to get it all out. During the process though he chipped the nikasil on the top edge of the barrel. Turns out he really only works on older air cooled motors.

I attached some pictures of the chip. My thought process now would be to put it back together and measure the squish then tear it back down to have it re-coated. Anyone see any issue with this and using 2 gaskets to try and get the squish back up to around 1mm? I won't pretend to know a lot about tuning of heads or barrels.

Thanks

Ouch! Unfortunately, had you posted before hand, we could've told you that was most likely going to happen, and saved you some money! From your description, the pitted surface was almost certainly due to a reused head gasket, allowing coolant to seep out from under it.

The only solution now is to replate (or replace) that barrel. Having it replated may well see yet another "skim" taken off the top of it, as many platers seem to like to do, so you will need to carefully measure it up once it's returned.

No inherent problems with using two base gaskets on that barrel, other than skimming off the top of the barrel and then lifting it back up with thicker gaskets will alter the port timing a little. If you're running a stock road bike, it's going to be of little consequence, but if you're going for performance, at best it's not going to help.

It's already recommended to run a 0.6mm base gasket on the front MC21/28 cylinder (once delimited) to reduce the chances of detonation, but by the sounds of things, a 0.6mm gasket is only going to bring you back somewhere near stock. If you have the barrel plated and they take yet more off the top, and you're using crap low octane US unleaded, you're probably better off now sourcing a good, standard used barrel, in my opinion.
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Andy.
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Thanks a lot for the help. You answered all of my questions.

The rings won't get close to that chip . Another option would be to put a detonation ring in there and that would clean out the chipped nickasil anyway .
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NSR300

A groove for the det ring would need to be cut, and that very often leads once again to chipping of the plating. It's the machining to the edge of the plating that chips it away, and is more often than not, unavoidable. Det rings are not the answer.

Done properly, the [detonation ring] groove is cut, then the barrel sent for plating. Once returned, the det ring is pressed into place, and finished to perfectly match the "new" bore.

You may get lucky and cut a groove without more damage to the plating, and consequently not need to replate, but I'd put 50p on it not being the case.

Irrespective of all that, a good chunk has been taken off the top of the barrel, the plating is now chipped, and in need of repair... that barrel is scrap for anything other than a 40hp stocker that never ventures more than a couple miles/walking distance from home. Bite the bullet, and source another one.
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Andy.
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On the subject of cylinder repairs & plating, can anyone recommend re-plater here in the UK?
Eggsy.

We offer cylinder repair/replating via NSR-WORLD Performance Engineering.
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Andy.
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Is it possible to re-plate a B or C cylinder to the specs of a A cylinder/B piston? Basically, if I source a cheaper cylinder with good gasket surfaces but needing a re-plate, can I get it re-plated to match piston clearance on a B piston?

Yes. We always have our barrels matched to the piston, regardless of the ID mark(s).
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Andy.
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