Howcome?

[canyncarvr]

Remember this?



Got rid of it. This past weekend.

Replaced the FRP ported USChrome replated cylinder with an OEM (not ported, electrofused) cylinder last week. Same jetting just to keep that a constant for starters. 40/152/DEK-4/#7TV AS at the SSS..2.5+

After the rings seated there was nothing on the fender but a bit of smoke. That over the course of a 100 mile ride last Saturday.

The key was on the removed piston. Thrust faces (front/back) were perfect carbon-wise. Not a speck of carbon past even the first ring. But, on the pin axis? Pretty bad. Plenty of carbon.

Forensic conclusion (my guess and the opine of a good bike tweaker that looked at it too): The cylinder was out of round when I put it in.

I don't have a bore gauge. I did check piston/cylinder clearances when I put it together, but ON the thrust faces because that's what needs to be known. I don't know that a feeler gauge would tell much in this case anyway had I measured on the pin axis.

The 'new' OEM cylinder? Lots more spunk than the ported/plated setup. That's not an apples/apples comparison though, as the ported cylinder had been on a good while..over two years.

...don't ride as much as I used to....

Still, the current setup seems stronger pretty much across the band over the ported cylinder. Won't know that until I get IT replated (Langcourt) and 'recycled'. Re-motorcycled, that is.


It's a relief getting rid of the goo. Flat embarrassing having the junk all over my helmet, my jersey, and dripping onto the swingarm, wheel and rear brake caliper. I'm sure everyone that sees it thinks, 'Gee. Too bad he can't SPELL r-e-j-e-t!'

It ran good though. Well, as good as it could. Kept up pretty well with 250s.

I wonder if the oem cylinder will run without toluene.... Haven't tried that yet.

Another clue: The crankcase had an unusually large amount of oil in it. There is always enough to coat the crank weights when you take the cylinder off, but this time it was t-h-i-c-k with oil.

Imagine that!

If you send your cylinder to USChrome, here's yur sign!

[strider80]

Wow, good to know. Must feel good to make progress on the problem. Thanks Canyn for the info.
Scott

[IdahoCharley]

I'am glad you got your engine straighten out and will not be dragging spooge into the laundry room anymore - bet the significant other is happy also.

You may miss the impregated (sp) smell on your skin/hair for a few weeks but I understand the key to fixing that problem is to take weekly rides for the next year or two so that your body doesn't have sever withdrawal symptoms.

I certainly think U.S. Chrome screwed up your cylinder based upon the pictures you posted - never seen so many pot-holes in anything else other than Idaho county roads.

My question/comment is - with a typically boring bar I think it would be hard to machine stuff out-of-round. (Off center - yes: wrong angle - yes: wrong size - yes.) Isn't it more likely there was an additional problem with the piston sizing?

[MXOldtimer]

I had US Chrome do my BB on my 02 YZ-250/280F. I ran that engine very hard, bounce'n off the rev limiter for over a year and had no problems. To tell you the truth I was shocked how well that engine held up.

[strider80]

Maybe they clamped it in the mill vice too hard when they were boring it and it was bored out of round? I would assume they would have a nice fixture to hold it though?

[dave04kdx]

Good to hear that you got your spoo problem solved! Maybe the porosity of the US Chrome “Replate” had something to do with it also. The swiss cheese look of their work could have been trapping an excess of oil.

[bradf]

Thinking back on all the discussions about the cause of your spooge, and now knowing the culprit is what you always thought it was, shows that the experts are not always the ones that think they are, but the ones that are prooved to be. Maybe you should shine it up real good, turn that sumbitch sideways, and shove it right up US Chromes' ass. And hand them their sign of course.

[fuzzy]

[Indawoods]

Does anyone have pics of Langcourt's work?

I am tearing mine down this winter to check condition and put a Wiseco piston in it. As some may recall I put a Pro-X in last winter and seems to be doing fine but have noticed how Wiseco fitted KDX's over-rev much better... instant R's over a Pro-X.

I don't think it's my imagination either....

[IdahoCharley]

I do not have any pictures of Langcourt's work but I've seen three of their replated cylinders and they looked very, very good.

I've also seen some of U.S. Chrome's work (~8-10 cylinders) and had them replate a 380 cylinder for me and they all looked very, very good.

Bottom Line - Sorry, but I'm not sure that a picture is going to do you any good relative to determining whether or not a replated cylinder is going to turn out any good.

[TopperHarley]

My 03 220R cylinder is being delivered today from getting refurbished at USchrome. It will be going on a bench build (extra engine) so I wont be using it for a while(hopefully). I sent in my new Wiseco piston with the cylinder so they could check to see the clearance were in specs. I am going to take mine to the local machine shop and have it measured with the piston to make sure it is all good. Sat night I will be dismantleing the 05 to install new piston, RB head, airstryker carb, VFIIIreeds, FMFtorque pipe and silencer. Will also be checking the cylinder measurements for factory defects. Very few hours on bike, still under warranty. If the cylinder is not in specs, I will be sending it back to KAWI for a warranty replacement. If this be the case, I will use the USchrome cylinder to get the 05 ready for some fall riding. Nothin like having lots of extra parts. Anybody need a nice clean head off an 02?

[TopperHarley]

UPS just dropped off my cylinder. It look great, no swiss cheese look, smooth as silk, nice hone job. Piston fits very nicely throughout the cylinder. I guess it is a hit and miss thing with USchrome.

[dave04kdx]

I’m glad that the work U.S Chrome did for you turned out ok. I had horrible experience with them. I work with equipment and machines every day here at work and understand that sometimes S#%T happens. The thing that separates a reputable company from a hole in the wall is admitting that a mistake was made and standing behind it. In my case they did neither and pretty much told me tough luck, don’t like it go somewhere else. This happened over a year ago and I’m still steamed. I did the top end on my brothers KDX for him. I had a couple of studs that I couldn’t get out so I made arrangements for US to remove the studs for me. They didn’t remove the studs, just ground them off flush, did a half ass re-chrome and sent it back to me that way. No body would stand up and say that they were in the wrong. $350.00 later I had to spend 4 hours of my time building a jig to hold the cylinder so I could use an EZ out to remove the studs.

[TopperHarley]

GEEZE! thats really messed up! Thank god I was able to get my studs out. Maybe they are under new management now. The guy I talked to seemed pretty cool and cooperative. they even took out my dowell rods and KIPS shaft seals for no charge and returned them to me.BRAIN FART! I forgot to remove them. I do recall him saying that if I couldnt get the studs out that they would try but would not be responsible if they broke coming out. yours must have broke. Next time try some heat in cojunction with some cutting oil ,liquid wrench or PB blaster. RB says to put a thin coating of water proof grease on them when you put them back in so you hopefully wont have problems getting them out next time. They do carry a 1 year warranty. About this timen ext year, I will be taking her apart for an inspection. Any problems and I will be sending her back for warranty repair. Of course warranty will be voided if I run without an air filter, drop sand down the plug hole, have a lean seize, etc. But then , i'm smarter than that...most of the time...killed alot of brain cells when I was younger..OOPS!

[fuzzy]

You, know I just thought of something. Did US chrome bore the cyl or just replate? Fredette could be the cause of the out of round bore along with the crappy port job. He's the KDX god, but lets face it he's no engine builder...

[krazyinski]

well sombody at his shop does ok cause they built my engine and it runs fine for over a year.

[tim]

My question/comment is - with a typically boring bar I think it would be hard to machine stuff out-of-round. (Off center - yes: wrong angle - yes: wrong size - yes.) Isn't it more likely there was an additional problem with the piston sizing?

I have to agree with Idaho on this. I've been building tractor and auto engines for a while and actually seeing a cyl. being bored I don't think it can be bored out of round.

I don't know much about the replating prosess but maybe it can be plated out of round. And then when the hone it it will stay that way.

If some one out there knows the prosess of plating please try to explain it or if you know where an article or info on it is let me/us know.

[fuzzy]

Bores can most certainely get out of round while being bored. The cutting causes heat, and there can be some flex going on. I know some kart engine builders that actually cryogenically freeze the cyl before boring (ANAL! but thse engines can turn 20k RPM).

Bores will also go out of round duing use, and this is more than likely the cause most of the time. This is also more than likely why Ma Kaw recommends the ABCDEF/New Cyl method of overhauling. By the time you get to "F" your bore is certainly going to be out of round.....and I'm not talking out of round to the point where your going to measure it with a tele guage, and a mic. Those are pretty much useless on a plated cyl anyway. We're talking seriousely high dollar machines here, but your running engine knows the difference. Tell-tale signs will be seen after running an out of round cyl as well...Just like CC's case. Maybe your cyl was kinda out of round before this saga started...

[tim]

The way I have seen it done is with a liquid cutting agent that also keeps it cool. But I guess if it is cut dry it could deform. Never seen it done dry.

[IdahoCharley]

I think the heat from a boring bar would be fairly insignificant in an aluminum cylinder. The lubricant would be for aiding the cutting operation and extending the life of the boring tool.

Cast iron cylinders (like those on a Harley) are installed in torque plates to mimic the distortion that takes place when a cylinder is bolted down to an engine block.

For a relative short cylinder water cooled (jacketed cylinder) like a dirt bike made out of aluminum I would be surprized is their is any significant distortion. (I due certainly agree that wear over time will result in a perfectly round bore becoming oval shaped along the piston thrust surfaces due to piston and ring loads)

The cryogenic process used or promoted by some manufactures is supposed to relieve internal molecular stresses based upon what I have read. I personally have no experience with cryogenic freezing of cylinders but I'am somewhat familiar with stress relief and beta phase molecular structures and the importance of the same related to material strenght properties.