125-200cc 90 hours on wr165 still like new compression

So my 2013 wr has about 90hr took compression test and still 195 psi but it should be time for a piston and rings you would think. I put about 60 hr on a year so there is no way it would make another 60hrs or would it. Haha. I have been running amsoil dominator oil at 38/1 with premium gas mixed with 1/4 vpc12 race gas.

Nothing better for nasty single track.

Huskys are tough and Ammsoil is some good stuff, I have way over 200 hrs (probably closer to 300) on the OEM piston on my WR250 and still 205 psi cranking compression.

So would it be safe to run another 60hr or am I looking for trouble.

What I do is a compression check and inspect my piston by looking at it through the intake with the reeds removed and through the exhaust with the pipe removed. 250s are bad about wearing and cracking the piston skirt on the intake side so I have a look every 6 months. I also look at the rings and see if they have any up and down play or if the piston just below the rings is showing signs of blow by. I really expected to have done the top end a long time ago but it looked almost new 4 months ago even though it's 5 years old. I'm sure your 165 sees more rpm than a 250 but it's not likely to let go all at once so maybe you should check yours more often and maybe if your piston looks good then just replace the rings and run it some more. I attribute the long life to proper tuning, good mix oil and good fuel.

put a new ring in it at the very least, but at 90hrs I would personally do a new top end. It's WAY cheaper than letting it go too long and having your cylinder repaired.

If you are wringing its neck a lot it is probably safer to do a new top end. I have put over 160 hours on a 165 piston and it was still easily in spec for piston gap and the ring groove was still tight but I am not a top end rider. These pistons don't have a particular wear specific point other than the exhaust bridge. Keep your old piston as an emergency back up.

Definitely inspect the piston for wear and at the least re-ring it.

I do wring it neck a lot so I will do piston and ring while apart. There has been a couple times stuck or in bad spots were it was held wide open so long I was thinking that had to have hurt it but I guess not. Never had it overheat or loose clutch even clutch feel never faded. Was thinking about new yz250x but changed my mind this bike is just to fun to ride.

my 88 250 has 215 psi after well over 200 hours...so its not crazy. its always been jetted right, klotz super techniplate, warmed up rode easy before pounding on it, and a clean air filter..i bought the bike in 98 or so as NOS so im only owner.. im doing a topend first over just out of fear the stock cast piston will break. ring is still in spec.

The stock piston on a 88 husky was probably forged.

i know all the factory units were mahle on the primary kickers, wasnt aware any were forged.

Well got piston out and looks very good like new almost inside very bright and shiny for 90hours. Ring end gap measured 0.457mm or 0.018 which is really good looks like it could have went a lot longer. No carbon deposits. Not sure if the Lectron or amsoil is what helped it last so good I rode it as hard as I could. What should new ring end gap be. Cross hatching still looks good in cylinder.

Look how shiny and new looking inside crazy that a 90 hour piston.

No cleaning just running very clean I guess.

That is typical running with amsoil 2T oils. New end gap is ~.011", .018" is about when you should re-ring. Piston is good for at least that many hours again. Most of your ring wear is going to be at the exhaust port bridge and my guess is it is starting to get a sharp edge there.

There is a funny spot on exhaust bridge that a different color but it smooth and can not feel it with finger nail so I figure it ok for another 90 hrs. Hope I am right.

Yes, when they bore/re-line the cylinder they relieve the exhaust port bridge slightly and it isn't a perfect match to the cylinder radius. This causes the uneven contact patch. Looks good otherwise and the power valves look nice and clean.

Ok so for everybodys reference I feel fairly comfortable telling people they can run 80-90 hours as long as jetted right with good oil. I very rarely use the low end on bike if I do it right back to top end so even if motor is rode hard this motor combination is very reliable. Another note is my bike never has any spooge out the silencer and believe the lectron can be set to run perfect and stay that that way once set. Thanks Wallybean and after new piston and rings and getting suspension revalved hoping I get another 2 years or 90 hours out of bike and will know next time to just order rings since the piston I pulled out is in great shape and can be reused next time if needed. How long is cylinder plating usually lasting will be next question?