KDX 200 Engine Rebuild

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sterlin44
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KDX 200 Engine Rebuild

Post by sterlin44 »

I started tearing down my 1996 KDX 200 motor to inspect it. Looks like I'm going to need replating and a piston? Here's a link to a ton of pics of the cylinder. http://imgur.com/a/TTj9G As far as the bearings are concerned, I could feel no vertical movement.
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SS109
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KDX 200 Engine Rebuild

Post by SS109 »

What's the scoring on the piston from?
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Re: KDX 200 Engine Rebuild

Post by 6 Riders »

Man that piston scoring looks terrible. Dirty or no air filter?
Yes it does need a replate, the electroplating is worn out.
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Sullyfam
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KDX 200 Engine Rebuild

Post by Sullyfam »

Looks like dirt or water got past your filter and pretty good blow by from worn rings. So yes new piston and rings.

The cylinder looks fine (no repairs needed), but cross hatch is gone so I would replate.


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Chilly
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Re: KDX 200 Engine Rebuild

Post by Chilly »

You better just go a head and do the bottom end to while your waiting on the cylinder to return from replating. I learned this the hard way.
sterlin44
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KDX 200 Engine Rebuild

Post by sterlin44 »

The piston looks much worse in the pics because of flash, but it's still kinda bad. Scratches are just deep enough to catch a fingernail. I'm pretty sure it was from the bike being drowned, and sucking up dirty water. So replate, new piston and rings, and possibly bottom end rebuild? I know it would be a gamble to go without one, especially with the bike being as old as it is, even though the bearing play seems within spec.
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Re: KDX 200 Engine Rebuild

Post by Tedh98 »

Did you submerge the bike or did the person you bought it from do it?
sterlin44
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KDX 200 Engine Rebuild

Post by sterlin44 »

Sadly, I did. Back in my younger, more stupid days. It filled the cylinder and I just wrung the filter out, kicked the water out of the spark plug hole, and got it running again. Oops.
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Re: KDX 200 Engine Rebuild

Post by Tedh98 »

I would vote for rebuiling the bottom end as well. At 20 years old, bearings and especially seals dont last forever.

If you didnt fully heat/evaporate the water out of the bottom end and/or change the oil several times and then let the engine sit, the bearings probably arent in the best shape.

I would hate to spend all that money on a new top end and then have something in the bottom end take it out.
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