exhaust ports

Joined
Oct 29, 2007
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#1
I have a 91 kx 80. The bike was in pieces when I bought it. My question is that there is a tiny tiny nick right under the bottom side of the exhaust ports. It is smooth and i cant feel it with my finger. Did I say tiny. Someone told me to just buy a new stock piston and rings. Will the new piston and rings be all right in it and how much if any compression will I loose at the bottom of the stroke.
 

Studboy

Thinks he can ride
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Dec 2, 2001
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#4
Check to make sure that you don't have a plated cylinder first. If a magnet doesn't stick to the bore, then it's plated.
 
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Feb 10, 2007
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#5
Studboy said:
Check to make sure that you don't have a plated cylinder first. If a magnet doesn't stick to the bore, then it's plated.
Yep...I forgot to add that to my previous post. :whoa:

Rotor
 
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Sep 12, 2007
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#6
FIX IT the exhaust port get extremely hot and any imperfection could cause problems

but on the other hand if you cannot feel it at all and you are only putting the bike around the yard and not out on trails it might be ok if you spend an hour honing the cylinder and you dont mind replacing pistions and rings and possibly always having a compression loss issue.

It is hard to judge what a "tiny nick" is but remember that cylinder is suppose to be perfect and a tiny nick could and probably will cause failure. So do what studboy said and then decide wether to hone it, sleeve it, or bore it.

~Brian
 
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#7
What if it is a nikisil plated cylinder. Can I have that bored out and if I can about how much does that cost?
 
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#8
If it's plated, you can still get it bored and replated. You can even get a big bore kit.

Cost will vary. US Chrome is highly recommended.

Rotor