A few questions about my 94 kdx200

ubareddition · Post by **ubareddition** » 10:20 pm Oct 03 2016

I just looked up 4 corner seizure and I don't think that's what I have. there are only 2 marks on the piston that are noticeable. And they are both on the left side and correspond with ports on the cylinder. Idk much about what proper chamfering but is there a chance that improper chamfering on the intake side port caused those gouges. So quickly? Also my last piston was way worse than this one. Wayyyy worse. And the bike still had compression and ran. But this one does not. Why?

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ubareddition · Post by **ubareddition** » 08:02 am Oct 04 2016

Guys I think I'm going to contact powerseal USA about this and see what I say. I know I properly lubricated both piston and cylinder. I know it didn't over heat. I know that I allowed it to warm up before I started to ride it. And I didn't ride it hard. I slowly worked my way thru the gears and kept it at a steady rpm once I reached 4th gear. Was just going to the end of the road and then I was going to turn around and go check everything at my garage again. And it died before I could get to the end of the road. Less than a quarter mile. If it was exessive piston expansion I would think there would be 4 evenly spaced wear marks on the piston and all the wear marks would be the same as far as severity. But the ones on the exhaust left side of the piston aren't that bad. But the ones on the left side of the intake are very bad. I don't think it's user error.

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Post by **KDXGarage** » 09:28 am Oct 04 2016

That sounds like a legitimate concern.

ubareddition · Post by **ubareddition** » 03:53 pm Oct 05 2016

So I just got an email from powerseal usa. They want me to send them the cylinder and the piston for evaluation. *sigh* I kind of want to have it evaluated by a 3rd party before sending it off to them.

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Post by **KDXGarage** » 05:01 pm Oct 05 2016

They are the only ones that might replate it for free or a discount. Send it.

ubareddition · Post by **ubareddition** » 05:29 pm Oct 05 2016

There is a local bike shop that is recommended in town. I may just have him just look at it and tell me what he thinks.

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ubareddition · Post by **ubareddition** » 05:30 pm Oct 05 2016

I mean shouldn't the edge of that be beveled more?

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pumpguy · Post by **pumpguy** » 05:51 pm Oct 05 2016

IMO, port chamfering is a precaution to prevent catching a ring on the top or bottom edge of a port. Doesn't look like that happened in your case.

You might want to check the diameter and roundness of your cylinder's bore. Not enough clearance between piston and cylinder bore or out of round bore could contribute to what you now have.

Checking the clearance between piston and cylinder bore is something I always do before assembly. But then, I have the precision measuring tools and know how to use them. I realize this is not true for all riders.

As an aside, I sent my new piston and old cylinder to Millennium for re-plating. When they came back, I measured the parts and found the clearance a little on the high side compared to what the manual calls for. Hopefully this extra clearance is a precaution to prevent the type of seizure you experienced.

ubareddition · Post by **ubareddition** » 05:55 pm Oct 05 2016

pumpguy wrote:IMO, port chamfering is a precaution to prevent catching a ring on the top or bottom edge of a port. Doesn't look like that happened in your case.

You might want to check the diameter and roundness of your cylinder's bore. Not enough clearance between piston and cylinder bore or out of round bore could contribute to what you now have.

Checking the clearance between piston and cylinder bore is something I always do before assembly. But then, I have the precision measuring tools and know how to use them. I realize this is not true for all riders.

As an aside, I sent my new piston and old cylinder to Millennium for re-plating. When they came back, I measured the parts and found the clearance a little on the high side compared to what the manual calls for. Hopefully this extra clearance is a precaution to prevent the type of seizure you experienced.

Can you give me what those measurements are so I could check?

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ubareddition · Post by **ubareddition** » 06:25 pm Oct 05 2016

I just broke out my old micrometer or whatever it's called. It's an old one my grandfather gave me from when he was a machinist. I think it's accurate.

I measured the piston to be 2.590 inches. Or 65.786mm.

I measured the cylinder to be 2.595 inches or 65.913 mm.

Which would be a difference of
.127

I'm not sure if that's within spec or if that's consistent throughout the whole cylinder.

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Post by **KDXGarage** » 06:47 pm Oct 05 2016

wrong tool for the job. Sorry.

pumpguy · Post by **pumpguy** » 07:06 pm Oct 05 2016

Agreed.

I use micrometers and telescope gauges. An ID mike for the bore will work too, but it's best IMO to use it like a telescope gauge and measure across the tips with the same micrometer used to measure the piston OD.

What's important, really, is not the measurements but the difference between the 2. That's the clearance which is the most important thing.

6 Riders · Post by **6 Riders** » 11:24 pm Oct 05 2016

Pumpguy, the "excessive" clearance is because forged pistons expand a lot more than the stock cast pistons do. W/O that extra clearance, well you get a 4c seizure.

david · Post by **david** » 08:26 am Oct 06 2016

You can use a feeler gauge to check your clearance. .003-.005 feelers will curve with the cylinder and slip between the piston skirt and cylinder wall. No need to buy a bunch of expensive micrometers and telescoping gauges.

pumpguy · Post by **pumpguy** » 09:32 am Oct 06 2016

Mine was a stock OEM 200 piston which I believe is a cast piston.

Checking clearance with feeler gauges is okay I guess, if that's all you have. IMO it would be difficult to check for an out of round bore that way.

black · Post by **black** » 10:20 am Oct 06 2016

reading thru this thread......

I never ever want to touch my bike again unless to put gas in it.....

Seriously keep at it.
This is all learning experience. If I was closer I'd help you. ( north of Boston) or at least cracka beer with you

ubareddition · Post by **ubareddition** » 05:54 pm Oct 06 2016

I called a guy i know pretty well who does machine work for me on project cars I work on. He has a full machine shop with all the bells and whistles. He's gonna look at it and tell me what he thinks. Then either way I'm prob gonna send it back to powerseal. I just want a 3rd party to look at it. I'm not saying It's impossible I screwed it up. I'm just saying it's highly unlikely. If I screwed it up I screwed up and I'll pay for it. But if the machine shop says it's wrong and powerseal says it's fine I'll at least have a leg to stand on to make a complaint. Instead of them having all the evidence and me just having a gut feeling.

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Post by **KDXGarage** » 06:09 pm Oct 06 2016

That sounds like a fair assumption. Good luck with it.

pumpguy · Post by **pumpguy** » 06:18 pm Oct 06 2016

Good move.

Ask for an evaluation in writing, on the shop's letterhead. This will be useful if their evaluation shows defective workmanship. IMO, the most important issue is the clearance, although with a damaged piston and bore, that might not be exactly the same as it was before the seizure.

I was about to list the clearance and tolerances according to the manual, but mine is a '97 H series, while yours is a 94 E series. I don't have the numbers for the E Series.

Typical clearances for 2T engines this size are .0032" to .0035" or maybe a little bit more.

Let us know how this all works out.

ubareddition · Post by **ubareddition** » 06:38 pm Oct 06 2016

Also I'm having other issues. I swear to you this bike is cursed.

I cannot get it into neutral. Idk even what gear I'm in. It goes up one gear and down one gear. But won't go anymore than that in either direction.

Also the transmission oil drain plug is stripped. I tried tightening it and it just kept spinning.

Also clutch still won't disengage.

Idk what the hell with this thing anymore. I'm gonna change the oil. And push it around and see if I can get it to free up.

I gotta take the inner clutch cover off to take a look at that spring anyway. So we will see what else I'll find.

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