Put new piston rings in but dont know the timming marks for it does anyone know

The piston ring opening should have a spot on the piston with a little nub to align it. If it doesn't then just make sure the ring openings do not line up together. As for putting the piston in, there should be a mark on the top that will go toward the exhaust side

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Does it have electric start? This makes it a little more difficult to see the T mark on flywheel.

T is usually the mark on the flywheel and there's usually a mark on the cam sprocket and head to line up. you can google up a service manual too most likely.

i need help please i have a 2000 yamaha bear tracker 250 i did a top job on it i replaced the piston and rings but didnt put a new head gasket i put it back together and she wont start soundss like it doesnt have enough compression any ideals and also i dont know how to set the timing can anyone help me out please

The top rings are the same it is the oil/scraper ring (if used) that is different and goes in the lower slot.
Place the gaps 270 Degrees apart and that's it.

possibly you are 180 degrees off.
the timing marks are dimples on the gears to align up.
paint will be no use at all to use and have never heard of anyone using paint .
use paint on a crack balancer for the timing mark ony

Your problem is quite simple as what you done is rebuilt it with new piston rings i expect ,,but what you dident know is how to go about it SO what you have done is to fit the rings upside down ,,or ,,you have broken the new one putting it in ,,or,, you have got the wrong ring for the job,,or you dident hone out the cylinder the correct way and you took the lip of the cylinder but to much ,,or ,,the piston groove was to big alowing the piston rings to flap as it goes up and down,,and if 2 or 3 ring piston the ring gaps have to be (being air cooled) reset at 4 thou(.0004")(per inch per bore) and all rings have to be staggered,, 4 ringed piston stag to N-S-E-WEST,3 Rings in a Triangle 2 rings Opersit each other and 1 ring any where if the piston isent pined.
So let me know how you get on and work by the above and you will have a good bike again. Ron
New gaskets and (no goo ) to fit them on with and away you go
Let me know how you get on Ron

Put the piston in with the mark on the top of the piston facing the exhaust port of the cylinder. put one circlip in the piston in the bore seated correctly in the groove. place piston over rod facing correct direction and insert wristpin into piston and through the rod needle bearing in the top of the rod. insert other circlip and seat correctly in groove. install compression rings with letter or any markings facing up. markings usually located at end gap on either side. install oil ring with straight ring on top squiggly ring in center and straight ring on bottom all in the same groove which will be the lowest groove on the piston.stagger all the ring end gaps. do not let all the gaps line up. install base gasket on engine case. clean everything and make sure everything stays clean. slide cylinder over piston and compress rings with fingers and finesse cylinder over piston. do not force. put nuts on studs and tighten to spec in service manual. install head gasket correctly and put head on and put nuts on studs. tighten to spec. reassemble rest of motorcycle and get hurt! have fun

it could be a piston broke or an oil ring

if the timing chain is off i dont think it would run, id suggest getting you're cams checked and reseat your valves, i have the same bike and an electronic copy of a repair manual, not for the exact same bike however. i have not been able to find the correct copy.