I have a few questions about this:
- What are the tolerances for the barrels? I didn't see them in the haynes.
- If the barrels are out of spec how much can you bore it out if you still want to use standard pistons?
- Would you use a torque plate?
- When using a torque plate you use the old gasket or the new one?
- How to deal with the nikasil coating, how thick is it?

Hi, nc30 barrels are steel, not nikasil plated.
Sorry cant answere the other questions, a honda dealer you be able to sort you out i would of thought.
Cheers
Ian

As Morespeedvicar said, the cylinders are a steel liner.

You cannot bore the cylinders because there is only one piston size. Best you can do is hone them to suit new rings. Honda service manual says 0.10 mm service limit and 0.010 - 0.045 mm is the spec clearance.

New pistons might be slightly larger than your used ones and therefore make the clearance after honing smaller. Also coating the pistons might ne an option to tighten up the clearances.

Last resort is to have the cylinders resleeved back to OEM spec.

What the hell is this: http://www.ebay.com/itm/High-Performanc ... c0&vxp=mtr

$100 for 4 pistons including rings and pin, I would say a copy of OEM Honda, quality unknown.

Honda does not have oversize pistons for an NC30 ie there is no part number in the parts listing. None of the reputable aftermarket piston manufacures list the NC30 either.

My last statement is not strictly true, there is a big bore piston kit from JE (TTS UK) and costs significantly more than $100.

magg wrote:My last statement is not strictly true, there is a big bore piston kit from JE (TTS UK) and costs significantly more than $100.

Yeah 8x more http://www.ebay.com/itm/HONDA-CBR-VFR40 ... 51ac00418c

People have been using these cheap kits successfuly in 70's era bikes. I might order a set and make measurments but I can't tell how strong the casting is from that.

What kind of coatings are there? I found these: http://www.techlinecoatings.com/BulkEngine.htm

I really don't understand your thinking.

Do you even know if your cylinders are worn yet or is this just another hypothetical question?

If you replace the pistons with those unknown chinese ones youll be down 100 dollars before the gaskets and boring costs.

Why dont you just get a proven running motor with Honda quality pistons in it.

I will get another motor regardless. I'm just planning the rebuild and sooner or later there won't be any good motors left.
Btw I found versah gaskets for cheap 90 GBP delivered for a full set.

Neosophist wrote:I really don't understand your thinking.

Do you even know if your cylinders are worn yet or is this just another hypothetical question?

If you replace the pistons with those unknown chinese ones youll be down 100 dollars before the gaskets and boring costs.

Why dont you just get a proven running motor with Honda quality pistons in it.