250-500cc What piston rings last longest on nikasil???

Yep same for me, Start the bike on choke while doing up helmet and pulling gloves on at a push, Flip choke off and off I go to my local riding spot thats around 2 miles away and stick to the speed limits 30 and a 40 mph zones, Always put a finger on the rad top on arrival just to make sure alls ok then ring its poor neck down the farmers lane, sometimes turn around and go back for another run just to smell the trail of castor Ive left behind me

In my experiance 125's need next to no warming up seems the bigger the piston the more likly it is to seize.
So do you know what rings n pistons in your bike justintendo?

in my 360? it got a wossner size a after going to the machine shop and having them measure for me...everything else is either wossner or good old mahle.

Strange as i had cylinder bored out to D size wossner on 360 an was awesome has mental top end was brilliant untill 17hours then it picked up must not of warmed her up properly.
Similar exp with 250 new nikasil n piston to suit got an hour out of it before both were toast an i run at 33:1 all i can think is putoline mx5 aint up to spec for el huskyo.

yes, i hear you about mental top end. i did not think 360s ran that way. bad batch of oil? old maybe? hard to say but i wouldnt definitely get rid of it.

It was a 1993 cylinder so yup good top end was like warp factor 9 captin!
Will donate oil to a mate his honda cr250 runs sweet with it so he will be happy, time for maxima i think

tills he starts losing compression anyway

Haha dont think he would notice.

I never had any problems with piston wear... was using Mitaka, Vertex, ProX (they tend to crack), Wössner Pistons, never really had any problems seizing.
I m using STIHL Chainsaw 2stroke oil on alle engines (Banshee, YZ, WR, RM) and not having a single problem.
I would check if your Combustion chamber is been modified, maybe using a different base gasket, something not been lined up correctly? are there any "Guides" around the lower bolts of the cylinder to keep it in postion when bolted up?
Has the conrod been replaced with an aftermarket one? (had a similar issue on a 2007 RM 125- conrod was to long)

Yup rod is off a ktm 360 1997 it was identical on micromiter, also the cylinder studs have dowels on the right hand side.
How would a base gasket wear the rings excessivly?

i guess it could alter port timing and get a ring too close to a port??

Rings will be same anywhere through out stroke, port timing yes but that wont affect life span of rings, would it?
Idk

Maybe- but only maybe- the higher compression will cause more wear? whats the squish on your engine?
Are u 100% shure the rod has the same dimensions a sthe husky part? thats exactly what caused the RM 125 engines problems... rod lenght was different...

I set squish to 50thou any less and the bands doing nothing and unburnt mix is just there for the ride, an more and i would of had to machine combustion chamber.
That was done after the logged 60odd hours before it was just stock all i did was whip cylinder off new rings and put everything right back where it was.
Yup im 100% sure the rods dinentions are spot on identical.
Cheers for the heads up tho may just try mahle or veryex for rings an shove a new piston in after a replate.

did you hone the cylinder ? just thinking- sometimes you can feel where the ring stopped moving upwards in the cylinder near the head gasket- the will be a groove/edge, so with a new piston and a thinner base gasket the ring will always run against this edge wich causes excessive wear.

I rebuilt my 2002 360 with a new rod, newly plated bore, genuine husky piston and running castrol TTS at 40:1. We run the same mix in three different bikes which have all given excellent wear life.
I also noticed ring wear after about 50hrs when looking up the exhaust port. The rings are really thin compared to some of our other bikes so they will probably wear quicker on that basis. I was still quite disappointed considering the cost of the genuine parts and are now running wossner pistons with better results. I can also afford to give it a new wossner piston more regularly for piece of mind than a husky piston.
I feel the 360, being based on 250 parts, is just pushing the limits especially if you like using revs.
As its such a lovely torquey motor you dont have to thrash it, so it is worth it.

Were the rings installed backwards? by any chance?

That can cause excessive ring wear.