How do I know if my cylinder needs replating..??

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Davenay67
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How do I know if my cylinder needs replating..??

Post by Davenay67 »

I checked compression on my '00 KDX200 last night, and it's down to 120 PSI; bare minimum for an operating bike. I only have 2-3 more rides planned for this year before putting thew bike aside for the winter. Obviously, a new piston is part of the work needed during the off-season, but I don't know how to tell if my cylinder is fine, or will need replating.

Any pointers on what to look for..??

Thanks..!!

Dave. :)
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scheckaet
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How do I know if my cylinder needs replating..??

Post by scheckaet »

this is what I'd do:

tear down cylinder
take pics
wipe down cylinder wall
take pics
inspect for gouges, scratch....
deglaze it using scotshbright pad
take pics
inspect to see if aluminum is showing, thru the plating
inspect ring and piston too.
Adamnb1
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How do I know if my cylinder needs replating..??

Post by Adamnb1 »

if you take a scotchbright with soapy water to the walls to deglaze, you should be able to see the crosshatch pattern come through.. not necessarily perfect but you'll see it. Make sure the nikasil is not starting to chip away anywhere, especially around the ports, and look for other obvious damage to the walls. Google can show you lots of pics of good and bad cylinders.. and you can also post a pic up here if in doubt
You can also measure the bore with a micrometer to verify it's in spec.
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Julien D
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Re: How do I know if my cylinder needs replating..??

Post by Julien D »

The manual states 95-150 PSI. 120 is not all that low.
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Davenay67
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Re: How do I know if my cylinder needs replating..??

Post by Davenay67 »

Julien D wrote:The manual states 95-150 PSI. 120 is not all that low.
I too looked at my service manual after you mentioned this, and as you said, it states 95 - 151 as the usable range. Should have checked earlier myself, not sure why I had 120 in my mind as being low..??

Guess I'm still a bit too much of a 4T guy at heart.... :grin:

Thanks Julien..!!
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adam728
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How do I know if my cylinder needs replating..??

Post by adam728 »

What has the bike been in thd past? If I had a bike that consistently put up 150 psi, then I would call it time for rings once it was under 140 psi. Not wait to see 90.
Davenay67
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How do I know if my cylinder needs replating..??

Post by Davenay67 »

adam728 wrote:What has the bike been in thd past? If I had a bike that consistently put up 150 psi, then I would call it time for rings once it was under 140 psi. Not wait to see 90.

To be honest, I don't know. I only got the bike earlier this year. I wouldn't wait until the lowest compression number before doing any work on it, but I'm confident I can finish the year with riding before needing a top end.
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