I had this exact problem with one of my bikes. (XR650L). They cut the bore incorrectly. Slightly oval and with too much clearance. Did you supply them with the piston to cylinder clearance from the manual ?

My piston, rings and bore were all wrecked within 20 miles. It started smoking oil and had scores just like yours.

Its now getting re-done at another place. Another £400 worth of work.

Well thats's just for crap

I gave them 2 different cylinders I had.
One had some rust but was undamaged,
The other was my recent cooked up cylinder with aluminum stuck to walls.

They bore the latter one as they couldn't chemical peel the aluminum off.

It was fitted at shop.
I put the rings on then put piston in.

Any advise on what could/should be done at this point.

That's not a Wiseco piston , so I have to ask , was the end gaps verified ? Wiseco is really the only brand that is pretty reliable to have the correct endgap , other s can be good , but can be to tight . Also did you install the rings with the ends in the orientation as in the manual ? They do move around when running but it is needed to start out right.

I have taken a motor apart with only the few miles like yours has and saw similar marks (mostly "scuffs" front and rear where the push is toward in a running motor),everything felt smooth and seemed ok so I put it back together without changing anything, that motor is running fine to this day and had 190psi compression when tested later. It was the only topend I've ever taken apart with so little run time so I can't say it's normal for sure but I think it is how they tend to look till fulling seated and run-in.

When you put it back together clean good , very light oil in the cylinder then take it down the road briskly on the throttle and use the motor to slow the bike down , repeat 10 times going through the gears mixed with slowing down by the motor , not the brakes.

Picture of new piston box

All you can do is take it back to the place who cut it and ask their advice.

I presume you put the rings in the right order and the right way up.

Sent from my G7-L01 using Tapatalk

38k Miles time for new main bearings
 

Hi guys! Great thread!

My mike was redden by a friend of mine for 38K miles... it was never in the dirt and oil was changed every 2K miles or so. The bike is VERY clean inside the cases. I have seen bikes with 2K miles with a black coating inside. Cam is perfect with little to no wear, cam chain is still in great shape as adjuster was only out half way. The piston was very clean and rings are about 70% worn by measuring at the ring gap per the manual. The main crank bearings are worn as you can rock the crank in the case. The rod has no up and down play as well as the piston pin.

My plan is to:

1) New OEM piston rings with a hone job... the bike did not smoke at all before I took it down. You also can still see all the factory hatch marks on the cylinder wall!! That shocked me!

2) Lap valves with new seals

Piston looks great with little wear on it. I can feel a little play when it is in the cylinder but very little.

Any other ideas while she is all torn down?

I'm lucky this is the 1989 bike so it has the updated head bold pattern.

Thanks SO Much guys!

Eric

Hi Eric,
I would suggest starting a new thread.
But while you're splitting the cases to renew the crank bearings, I would check 5th gear for wear since this is a common problem, and renew as required.

Bob

hi what are the black marks running around the bore ? ,maybe marks from the piston rings where it has been left for a long time and left a very slight rust mark or indent ? also if you split the cases fit a new bearing for behind the sprocket as this can get a hard life due to maybe over tightening the chain ,steve