Cylinder recoating

[duke]

I am wondering what will be the symptoms that the cylinder on my 99 KDX 200 is in need of some new recoating. Some time ago, a local dealer, who I do not now trust, stated that the cylinder would be in need of a new coating. He also claimed that the carb was in need in of cleaning and that he would perform the repairs if I left the bike in the shop another week. Without belaboring the specifics, I was already without patience with the man and felt that he wasn't honest in his dealings with me. Case in point, when I tore the carb apart myself, I found it to be perfectly fine. I don't have the time to verify his claims of the cylinder coating by removing the cylinder, so I was wondering what are the performance symptoms that can be used to detect that the coating has worn away? Poor compression?

Bill

 

[YZ165]

:think: Sounds a little fishy to me. You can't get a cyl. recoated in a week unless you live nextdoor to L.A.Sleeve. I suppose you could "diagnose" bad coating by removing the head, but I prefer to have the cyl. in my hand. It's not that easy to see. I'd find yourself another shop. Good luck, YZ165

I see you live in L.A., so I guess you do live next door to L.A.Sleeve. Still sounds funny. Did he show you the damaged cyl.? Or did he diagnose the bike while it was still together?

 

[canyncarvr]

You could just look at it. You can't see all of the swept area (where the piston/skirt/rings go), but you could see most of it.

Without knowing what his point was (why it was 'needed') it's merely conjecture to guess at this point. Maybe compression would be low. Unfortunately the value of a single compression reading is iffy. It works best if you compare compression tests done over time on your bike. Then you would know (for example) that doing the test the same way with the same guage three months apart and getting a reading 40psi less the second time that something was wrong.

Maybe there was a tear in the coating beneath where the rings travel. Depending on how bad that tear was and what the subsequent damage to the piston was, maybe a compression test would tell you something, maybe nothing.

It's not real common for the coating to 'wear away.' If there is a problem with it, it's much more likely to be damage of some sort...a seizure maybe? Ingesting some dirt? Something major like losing a piston clip and having the wrist pin scraping a trough in the cylinder will be problematic. Compression will be poor..the bike would probably run awful if it ran at all.

The way to tell is to take the cylinder off, inspect it, measure it for taper.

If it's running just fine now maybe just ride it...check it next time.

He put it back together? With a new piston or with rings on an old piston? If it was damaged to much of any extent it should never have been put back together.

If it was just tapered a little bit, it's not anything that won't wait til next time.

Good luck!

 

[duke]

The engine was rebuilt due to there being a broken seal allowing tranny fluid into the cylinder, causing a seizure. The entire top end was replaced. I replaced the reeds myself and have found the bike to run great. It was just something I thought that I might be able to detect by means of performance and/or compression test alone.

Thanks

Bill