250-500cc Where do I go from here? Engine issue..

Only put about 10 hours on my bike so far, compression at 230 psi initially. I have been messing with jething throughout the time and finally it felt good. Was riding today in the 40°s running great. Went from 1.5 out on the pilot to 2 and felt no real difference was letting it idle and it started to die. Thought nothing of it and put it back to 1.5 out. Tried to start it an hour later and the Kickstart was going right through the stroke.. The cylinder had a nice score going down it that my fingernail could fit in..

Looks like a piston ring snagged.

I'd pull it apart and check crank bearing for debris.

if its catching the finger nail it means it will need replated or replaced. time for a wossner as well. as others suggested split it and clean/check everything, replace crank seals

Only found wiseco on ebay, is wossner the factory piston? I have some big decisions to make at this point.. getting here only took 30 minutes and a piston kit seems to be about 120$ plug base gasket ect, obviously no big deal.. Never split cases on anything before so a little intimidated there and not trying to get over my head. The score on the cylinder isn't as bad as I first thought. Thinking light sand paper, and vacuum and air hose out the bottom end. Thanks for the quick responses

no, wossner is a german forged lightweight piston that almost everyone has very good results with. i personally like them better than wiseco. i could be slightly biased tho as wossner has stepped up and is supporting the older swede motors as well. i cant say i like your plan as you may be already over your head but i would at least remove the engine so it can be tipped up and the crankcase flushed out...i risky rebuild plan imho.

Ok, I will call around for a Wossner. There were some small chips riding between the top of the crank and case. Was able to get those out and some tiny ones in the bottom of the case. Wd40 OK to flush with? As far as the cylinder and head goes I am planning on sending them out.

wd 40 or gasoline should work fine. when you think its flushed enough, flush it some more..

diesel works too. follow up with a ATF rinse to leave bottom end fully lubed up. diesel and gas will remove all oily film which you will need obviously.

Good luck with getting the old girl fixed up. I know it's a little late now, but this is why I always put a fresh top end on any used 2-stroke I get. When I picked up my 2000 wr250, it still ran good and compression seemed fine but this is what the piston looked like...! The cylinder was ok but I did touch up a few areas with fine emery cloth and a scotch bright pad. She runs great now!

wow

Don't use sand papar on the cylinder wall. Use scotch brite and some penetrating oil (my favorite is PB Blaster). If you try to clean the crankcase up without splitting the cases it is a gamble. If you leave one spec and it happens to get caught under a rod bearing roller or in a main bearing you will have a more expensive rebuild then the somewhat minor damage you have now. If you feel like gambling I recommend spraying with brake cleaner and blowing it out with compressed air until it is as dry and clean as you can get it. Then check crank and rod bearings for end play (not side to side) if you have any end play then tear it down, if not it's your gamble. The risk is a spec of metal stuck under a bearing roller will cause the bearing to skid and flat spot then with no warning all hell breaks loose in a small fraction of time.

I pull my reed block once a year to look for that wear pattern. They will run fine like that and bust a piston with no warning.

The pieces of metal are from the piston ring being snagged correct? I have been doing reading and from the pictures of my piston top and head those are signs of crank bearing starting to go.. but in my case it was caused from the rings or plating from the cylinder being pushed into the combustion chamber?

Powerseal out of PA can do the replate for 200 50 if welding needed, wossner for 130. Than bottom end options.. cost vs turnaround time vs future failure.

It's hard to tell from the pics, but it is possible that the metal fragments you see are from a broken bearing cage but that's just a guess without seeing it in person. That stuff has to be from something. If the rings are still in one piece and the piston is in one piece, then you've got to find out the source of the F.O.D. (Foreign Object Damage)

I'm thinking it's from the piston around the ring area

Does this bike have a power valve? I've seen them come apart and do similar damage as well as leave little metal bits in the top end.

its not hard to split em...tusk universal tools are cheap as well. winter is a good time to learn. if you want to play with old huskies its a wonderful skill to have. everyone here will walk you thru it if you want to go down that road. i wish i would have learned it before i did