would you recoat if brass was showing??

[est142]

97 kdx 220. runs mint. just pulled topend off for kips cleaning and winter inspection of piston. wiseco piston is in great shape. the stock cylinder is showing uniform loss of efusion coating near the base of the cylinder only, near where the visible ends of the wrist pin would pass. no gouges or heavy damage whatsoever to the cylinder. the two worn spots are about the size of a large chicken egg. Should I go for new coating of the cylinder? has anyone used uschrome? how much do they charge...and how do you contact them to get info on sending them your core? e-mail them?

if you have rechromed, i would really like to here from you. the motor is a 97, so yah, there probably is a hair more play in the lower connecting rod bearing than a brand new bike...but it is not at the split the cases point. i would prefer to keep the repair costs down, considering the age of the bike.
i am considering just re-ringing and using it the way it is. thanks for the input.

 

[canyncarvr]

If you have the time you might consider sending the thing to Forward Motion (Gorr). He will diagnose failures based on wear pattern.

I have no idea why there would be cylinder wear to the extent you indicate on a non-thrust surface that low in the bore. That big-end rod condition may be in worse shape than you think.

My cylinder was bored/replated thru FRP..and I've been told that he uses USChrome. My cylinder came back looking like swiss cheese...full of holes. Now....appearances may well be deceiving; FRP indicated there was some paperwork that came back with the cylinder that addressed the presence of those holes. I asked for a copy of it. Didn't get it. I did take the cylinder to a local hi-perf shop to get an opinion. The owner asked that if I ever found out for sure who did the replate he would like to know.....'cuz he wanted to be sure to NEVER use them!

That wasn't comforting. As long as it was being bored, why not bore it enough to make the replating thick enough to resolve 'hole' issues? Or...does USChrome think the cheese idea is a GOOD idea? Maybe they are oil reservoir devices?

 

[est142]

thanks for the reply cc. maybe i exagerated the size of the spots, i looked again and they are about an inch in diameter. they are only worn to the point of the chrome just being gone...there is no deformation of the cylinder or out of round egging. yah, i heard supposedly the pock marks after chroming, carry oil etc etc...sounds like an excuse on the fly statement to me. the engine really runs and sounds tight, zero piston slap or knocking. i dont want to make a decent running bike into a permanently disasembled parts pile, just because of a couple of worn areas on a cylinder. ??? though not technically perfect, i would prefer to just shine up the jug ,add some fresh wiseco rings,and get 2-3 more years of recreational riding out of the bike...then sell it as is. i dont think those lower end jobs are cost effective on an older bike.

 

[chiro972]

If the chrome is actually gone, you will likely run into problems. Remember that our cylinder is aluminum, The Nikasil plating is what allows us to get by without cast iron for the liner. Aluminum being rubbed at 5,000 RPM will wear out very quickly. Is the plating just discolored or is there actual aluminum showing?

If it is indeed through the plating, I wouldn't expect to get two years of running out of it, and I would be pretty pissed if I bought the bike from you after that and found the plating gone, regardless of how it runs.

 

[est142]

No, it is not aluminum showing. About 90% of the cylinder wall is bright reflective chrome. In the areas that I mentioned the shiny chrome has been rubbed away to reveal a metal that has the look and apearance of dull brass, like plumbing pipe. You can see what looks to be a brass liner inside the aluminum cylinder, if you look at the jug from the bottom or top.it looks like kawi lines with brass, and then puts the efusion coating on the brass liner.I may be wrong, but that's what it looks like. It is not a carbon mark(I wish it were), but it is not worn out to the aluminum either. I am surprised that no one has run across this before? Has anyone tried a rechrome for a decent cylinder that looks like mine?? Be nice if I had the $400 for the rebore to the 240...but the kids come first this close to xmas.thanks for the replies.

 

[DirtRoller]

This sounds like you are seeing the attachment coating that is put on before it is plated. The plating won't stick directly to the cylinder.
I heard somewhere that there is @ 4mils of this coat before you're through.
If that's true I don't know, but it sound like it's not worth the chance. Replate and be safe, check the cylinder for being round when you get it back. This sometimes is a issue with replating or boring it seems.

 

[Jim Crenca]

No experience on replating, but if the thing runs well and bore gauge / piston OD are close to right, I'd put rings in and run it. If it starts to sound or run funky, then replate or intsall a liner. I think the extra damage that might occur with leaving the bore as is, has a low enough risk level, and, I'm not sure failure would cost that much more to fix than a replate job any way.

 

[est142]

thanks for the replies. cleaned the kips and piston dome. i am going to re-assemble and run it as it was when i found it.. next time i take it apart though, i will have $400 ready for a new cylinder + piston just in case.