Does my CR250R need new Nikasil?

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#1
So I just bought this 2000 CR250R and it needs a rebuild. The piston is toast. It looks like its melted and smeared in two spots. The cylinder is really shiny in spots and looks normal in others, and it has two very small scars, so small you almost can't feel them. What do you guys think? Do I need a new cylinder, a rebuild, or would a hone job possibly fix this?

Another question is, Whats the best pipe for this bike, I'm running an FMF fatty and ive been told this pipe can kill your top end, which mine is long dead.
Thanks everybody!

?How do we post pictures here? I'll get some on if I can.
 
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#2
Are there any spots where the niksil coating has rubbed through and you can see the aluminum under it?

If so then you need niksil.

If things just look polished then you can probably get by with a good hone.
 
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#3
utrax42 said:
Another question is, Whats the best pipe for this bike, I'm running an FMF fatty and ive been told this pipe can kill your top end, which mine is long dead.
Thanks everybody!

?How do we post pictures here? I'll get some on if I can.
Who ever told you that is talking bull... :nod: Maybe he was referring to your "top end" power...
 
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#4
Your plating is probably fine,its flaking that you have to watch,and fools with hones! Make sure who ever does it is qualified! Has anyone tried sst pipes on hondas?
 

darringer

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#5
If the cylinder has aluminum from the piston on the Nikasil, it can be removed with Muriatic acid. It won't hurt the plating. Just be careful not to get it on the rest of the cylinder, as it eats up the aluminum rather quickly. Afterwards, wash the cylinder with soap and water thoroughly. Even if there are small bare spots in the plating, the cylinder is still useable. Unless there are deep scratches, or flaking Nikasil as stated above.

A friend of mine ran an SST on his '02CR250 when I had my '02CR250 with the Fatty. Everything else was stock. The only difference I noticed between the two bikes was his with the SST had just a bit more pull at the very top. Bottom and midrange was about the same.
 
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#6
mmz77 said:
Who ever told you that is talking bull... :nod: Maybe he was referring to your "top end" power...
Yes, sorry for the confusion, I was referring to the top end power. Thanks for all of the feed back guys I greatly appreciate your help!
 
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#8
It should be pretty thin. If you have pitting, a few small scratches, then you are okay. Actually, tiny pitting (kindof looks like a little bit of a haze of tiny bubbles) that helps keep the cylinder lubricated, but if you have any chipping of the plating at all you will need to have it bored and replated, or else you will scar up your cylinder and piston more when those flakes of plating come loose. US Chrome does a good job of it and it is reasonably priced.