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Well, I took my 220 top end apart to put a new piston in it. It looks like I'm going to be needing some cylinder repair done. I was hoping that one of you more experienced individuals could lend me some insight as to what kind of repairs I will be looking at?

These scores are only seen in the area shown. Can this be cleaned up with a 1mm overbore? Or am I looking at a weld/machine repair? This is my first top end rebuild that I've done, so I'm not sure if just a replate/hone would be enough to fix it? I wouldn't think so.





Thoughts? Any input would be helpful! I plan to take the cylinder to PowerSeal, they are somewhat in my neck of the woods.

Replate at Millennium Technologies.

EDIT: That's a plated, not sleeved, cylinder, correct?

BTW, if you don't mind my asking, what premix oil and ratio where you using?

Why not PowerSeal? I haven't heard anything bad about either of the two places; Powerseal was just closer to me.

Yes, that is a plated, non-sleeved cylinder.

I bought the bike several months ago and only had about 7 or 8 rides on it. For those rides, I ran 92 octane with Belray Super M mixed at 40:1.

Any idea how extensive the repair is going to be?

Tyl3r wrote:Why not PowerSeal?

Any idea how extensive the repair is going to be?

I've heard lots of great things about Millennium. I've used the twice myself with excellent results. Don't know much about PowerSeal.

What do you mean by "extensive"? You remove the power valve parts, clean the cylinder and send it to them. You pay them and they return the cylinder to you. Reassemble the cleaned parts and enjoy.

Mine was just as bad. $185 for powerseal to replate. 3-4 week turnaround right now. Mine should be back to me any day now.
Buy a piston and send it with your cylinder. You can get one through them, but it's about $20 more expensive than can be found elsewhere.

I just had my replated by Millennium and it's came back looking awesome. Better than new. Two week turnaround.


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I use Powerseal as well. Quick turnaround and good work.

Definitely send your piston with the cylinder.

Jethrobolas wrote:Mine was just as bad. $185 for powerseal to replate. 3-4 week turnaround right now. Mine should be back to me any day now.

Did they have to do any machine work to the cylinder to fix your gouges? Or did they just replate and hone?

Jim - I was asking about how extensive the repair work would be in regards to welding, plating, and machining operations... I understand the logistics lol

Thank you all for your input, I'm more than likely going to take the Powerseal route. I spoke with them today and they said 2-1/2 to 3 week turnaround. I plan to pack up the cylinder and piston and send it to them on Monday Wish I wouldn't have waited so darn long to get it apart

Tyl3r wrote:Jim - I was asking about how extensive the repair work would be in regards to welding, plating, and machining operations... I understand the logistics lol

My old KX250 cylinder was quite a bit worse than the one off your KDX. I think what Millennium did was chemically strip off the old plating, bore the cylinder slightly and replate with a "thick" plating. There was, IIRC, an extra $10 charge for the thick plating, on top of what they'd normally charge for a replate. (I'm not 100% sure how they remove the old plating, I'm just taking a semi-educated guess.)

I wouldn't worry about it at all, your cylinder really isn't too bad. If they couldn't fix yours, then they couldn't fix any of them.

From your photo, looks like it just needs a strip and replate. Same as mine.

Here is the home page. Plenty of info on their site including pricing.
http://www.powersealusa.com/

I think welding, finshing and boring is around 50 bucks, but yours does not look too bad from the pics. Is it a gouge or a circlip?

I just sent my 1987 kdx cylinder off today to Millennium as per suggested by people here. There website is awesome. I sent a wiseco piston and the power valve parts and head. I hope i get it back fast! Im still waiting on getting my mono shock back from rebuild from my local bike shop. Been few weeks, they said 2-3 weeks tho. Im going to be in deep with my KDX!

I am not suggesting this but just saying like if the gouges were smooth enough you could just keep running it with a new piston. The rings don't go down that far. You can see the bottom of the ring line about 1cm lower than the exhaust ports base.

What would have me wondering is what made those gouges. Gouges are mostly from the ports and up. Or on the sides for when a circlip lets go. Some thing must have come from the bottom stuck on the bottom of the skirt and refused to let go like a broken ring. What ever it was there may have been a few of them and they were harder than aluminium.

Check the bottom of your crank for bits of something and bearings and rod free play. I don't know if this would work on this motor but lay a strip of clean white cotton rag across the crank and feed it round till it comes out the other side. Then check for bits of some thing and does it stick to magnets.

Tioli wrote:I am not suggesting this but just saying like if the gouges were smooth enough you could just keep running it with a new piston. The rings don't go down that far. You can see the bottom of the ring line about 1cm lower than the exhaust ports base.

What would have me wondering is what made those gouges. Gouges are mostly from the ports and up. Or on the sides for when a circlip lets go. Some thing must have come from the bottom stuck on the bottom of the skirt and refused to let go like a broken ring. What ever it was there may have been a few of them and they were harder than aluminium.

Check the bottom of your crank for bits of something and bearings and rod free play. I don't know if this would work on this motor but lay a strip of clean white cotton rag across the crank and feed it round till it comes out the other side. Then check for bits of some thing and does it stick to magnets.

dirt will do it.

Yes if you forgot to put the air filter on. Still marks from the port down is unusual as the bottom of the skirt does not go up that high to expose the exhaust port and the rings don't go down that far. So how does it begin the marks?

I was thinking the same, probably dirt or sand or something snuck in there. I was looking at a lot of photos of damaged cylinders, lots of them had damage in the same area as mine. I'm not too concerned about it, I only had the bike for a couple of months, who knows what happened to the bike with its previous owners.

After I packed up the cylinder, I saw that the old piston had similar looking marks on it. I wish I would have noticed before I packed up the cylinder so I could have done more investigating. O wells