kx 250 94 top end rebuild (agen)

[staffylad]

never trust someone to do the work on your bike 

[Foxx4Beaver]

huh...do tell.

[staffylad]

should ther be any play on the pison from side to side and the arm moves side to sided but up n downs ok

[Foxx4Beaver]

hopefully you're experiencing this while the cylinder is off?? ....
there will be "some" side to side play...unfortunately I don't have the extra parts lying around to take pics to show you, but there has to be a little play, otherwise the rod would be tight against the piston...and it wouldn't be able to rotate as it went up and down...do you follow?

[staffylad]

seems a lot to me and the piston was moving side to side a lot aswell,its been scrapin up the side on the bore at the bottom,im in 2 minds weather to do this top end incase the conrods not right ,could ther possibly be the wrong size bearings in causing them to have toomuch play to cause the piston to do that to the bore ..

[Foxx4Beaver]

when your motor was rebuilt, what was claimed to be replaced?...it is possible the big and small end bearings were'nt replaced, and the ones in there now are shot....
if your cylinder is getting scored up, I wouldn't run it any more until you find the root cause of the problem....post some pics and even video so we can see what's going on, and hopefully be able to better help you.

[staffylad]

the cylinder heads off now on the bench,the crank is submerged in water,the bottom of the bore is scraped and so is the piston down onside,the scrap on the bore is at the bottom of the front ,he claimed to to have replaced the crank and conrod but it looks like my old crank with a new conrod wich is movin side to side and the piston was moving side to side a lot,they both seem to have a lot of play sideways,the top bearings look new and the rings are but the piston looks like my old one,it was running when I got it back,ive rode it once took it out wouldn't start took the plug off and it was sprayin water up,so I took the head off and I think it hasn't been skimmed but the play on the conrod has to be the reason for the piston scraping the bore? that's my thoughts so far lol ...

[staffylad]

[Foxx4Beaver]

hmmm ...try to get a few more pics of the cylinder plating, on the exhaust side too...it looks questionable in that one pic.

[staffylad]

[sandblaster]

The plating looks like it is worn out around the exhaust port, although it's hard to tell.
Get a feeler gauge and measure the crank to rod side clearance and tell us what it is.
I'm guessing that the cylinder was not plated or even honed before the new piston was installed, is that correct?

[staffylad]

yes its looking like the head hasn't been skimmed causing this problem so its a new top end build

[staffylad]

someone says don't skim the head do it yaself with a grindin plate becos they take toomuch off apparently and the bores looking like its nickel so I might just get away with rubbing it down and putting a new piston in + gaskets but I think I will get it skimmed as these are wer the problems started 

[Foxx4Beaver]

Motorrad turned a bunch of us on to Time Saver lapping compound....works awesome. You'll need a FLAT surface to work on...I snagged a nice piece of 5/8" safety glass from work and had it cut down to 20"x 20", it's a little big and heavy, but works perfect for lapping cylinders and heads...but any hard flat surface will work. You will want to pull the cylinder studs and lap the cylinder along with the head, so that BOTH mating surfaces are flat...no point in doing one and not the other.  



you can get it here, or other places that might be more practical shipping cost wise....you want the Yellow Label 100N as shown here...

http://www.ws2coating.com/timesaverlappingcompounds.aspx

[staffylad]

cheers beaver ive just been polishin me head I like to take the clear coat off and shine them up