Nikasil

[GPracer2500]

Are original 250r cylinders Nikasil coated? I know the CR250s got Nikasil in 1986 but I wasn't sure about the TRX.

[wilkin250r]

Nope. None, in any year 86-89, nor were the ATC cylinders. If you want a nikasil cylinder, you need to go aftermarket.

[Iliketogofast]

So, can the original cylinder be coated with nikasil, or cryo treated?

[Rich250RRacer]

Originally posted by Iliketogofast
So, can the original cylinder be coated with nikasil, or cryo treated?

I just had a stock cast iron bore cylinder Nikasiled by US Chrome. It can be finished at nearly whatever bore you want. My cylinder was at .050, but because of wear it wouldn't have cleaned up at .060, so I had it Nik'ed back to .050. It looks pretty good, but don't always expect perfection since you stand a chance of pitting from dissimillar metals. My cylinder had some slight pitting at the bottom of the bore, but since its below the ring area , there's no problem. Another option that US Chrome suggested is to have the stock sleeve removed and have an aluminum sleeve installed. With this your choice of bore sizes is unlimited, with little chance of pitting.

[BLACKeR]

Originally posted by Rich250RRacer
I just had a stock cast iron bore cylinder Nikasiled by US Chrome. It can be finished at nearly whatever bore you want. My cylinder was at .050, but because of wear it wouldn't have cleaned up at .060, so I had it Nik'ed back to .050. It looks pretty good, but don't always expect perfection since you stand a chance of pitting from dissimillar metals. My cylinder had some slight pitting at the bottom of the bore, but since its below the ring area , there's no problem. Another option that US Chrome suggested is to have the sock sleeve removed and have an aluminum sleeve installed. With this your choice of bore sizes is unlimited, with little chance of pitting.

do you know ball park prices for either option?

[Rich250RRacer]

A friend of mine gets a discount from US Chrome because he sends all of his micro sprint cylinders to them, so it cost me about $200. You can check prices here http://www.usnicom.com/. They don't do the resleeving but I believe they can refer you to a company that can.

[wilkin250r]

I can't see a whole lot of benefit to nikasil coating the stock cylinder. The main advantage to nikasil is removing the iron sleeve, and coating over aluminum. It allows better heat transfer because you don't have the iron/aluminum transition. It also means the cylinder and piston are the same metal, and thus have the same thermal expansion rates, therefore greatly reducing potential for seizure.

The only real benefit I can see is longer life. If you have a cylinder with an awesome port job, but it's on it's last bore, you can have the cylinder nikasil coated to save it. You still go through just as many pistons, so cost savings isn't a huge benefit.

[NEPA250R]

I recently had a mildly ported stock cylinder done by US Chrome. It is set up to use with a stock bore piston and rings. I haven't assembled the engine yet. From what I understand, a nikasil coating will reduce friction, which should mean less power loss due to friction, and more time between top end rebuilds. The only drawback I can think of is spending more money to have it recoated rather than just bored and honed, but I figured that I would give it a try anyway.

[matt250r21]

I have an 86 250R cylinder that has a custom aluminum sleeve with nikasil plating. The cylinder is ported for mid and topend power and runs a 66mm piston. This cylinder was personaly done for me by Scott Currier of Atomic Racing Engins. Its a really nice package and the port work and sleeve are like art work. Scott only built 3 of these that I know of and I've never scene another cylinder like it.

[matt250r21]

Here is another wish they were brighter, these pics don't do this cylinder justice.

[machwon]

Yes, you can resleeve a stock cylinder with an aluminum sleeve and then have it nik'd. I just did a stock one last year. Most all of the Duncan racing Hyperdyne cylinders were done that way.