1987 250WR piston or alternatives

I know this has been asked before, but I couldn't find a definitive answer... any sources for the non-power valve piston? I just sent HVA an email, but I don't see any on their website. The bike I just picked up has the original bore (piston stamped 66.44), but the skirt is cracked. I'm not sure if it needs a bore or if I will get away with stock piston size and a light hone.

If no sources are available, is it possible to fit an '86 top end and crank on this motor? I happen to have a spare '86 motor with corroded cases that would be a good donor for parts. I see in the parts manuals that the '86 and '87 have different engine case part numbers, so don't know if this is possible though.

case will be the same. crank cheeks were where the extra stroke came from. i am in the same boat as my 88 250 has been pulled until i freshen the top end. still has 215 psi but im worried about really high hours, lol..
worst case scenario you should be able to swap in 85/86 lc jug and crank. would be a shame as the stroker 250 is a sweet mill.

The original piston is a 2 or 1 ring ?

I'd love to know too, I have read that the powervalve pistons work in the 87/88 250 motors, anyone confirm?

THE ENGINE CASES HAVE A DIFFERENT PART # BECAUSE OF THE EXTRA LUG ABOVE THE KICKER SHAFT. ANDY AT HVA SAID HE HAS PISTONS FOR THE 87/88 250'S.

Sorry wrx but I'm unsure what you mean? What does the extra lug have to do with the bore and stroke?

My mistake, your comment is valid given that the '86 motor that the op has is a different bore and stroke to the later engines.

early cases didnt have the extra lug. so the part #s will be different. OP asked if he could use the parts from earlier motor. Justin stated yes the cases are the same or will work. i'm just confirming they will work and the only difference is the lug. OP stated part #'s for cases are different and thats why.

RUF - the piston is a single ring

WRX - thank you for the case info! I knew about the extra lug, but didn't know what year it was implemented. My 86 motor is stuffed in a box somewhere in my collection of parts and I haven't had a chance to compare it to the '87 yet.

Below is a photo of the cracked skirt. I only rode the bike around my yard once - glad I decided to tear into it before I ran it any longer... although it ran very well and I was tempted. BTW - I could clearly see the cracks through the exhaust port by just removing the pipe, so if anyone else out there has concerns, it is an easy check.

these Swedich Huskys are like small block Chevys. a lot of interchangeable parts if you know what you are doing.

Original piston has one ring, 86 engine components will swap around but you won't have the sought out stroker motor any longer. Not worth it if you ask me . I think I did see Andy say they had pistons available for the 87 now also.

Any idea of $$$???

the only 250 pistons i know of are from uk andy...i dont think ive ever seen the 240 ones..he has said the powervalve ones will work in the non powervalve engines.
tried to do a quote, can't remember how tho. lol
don't know what price is ?

the piston might physically fit but the skirt is set for a power valve to be functional
you will have a very pipey bike with the valve locked open or in your case non existent
keep looking or swap in your 85 bottom end
the crankshaft outer diameter is the same for 87 and pre 87 they just offset the pin
they will fit the cases
the reason for different part numbers is case design differences such as making the countershaft seal non removable and whatever update was deemed important

What's the bore size? That piston has been loose in the bore slapping.? Mic the bore top to bottom.

While its apart are you going to do the crank bearings and seals too?

With my bad luck I learned to rebuild it all or plan on n doing it again.

The main difference in 87-88 cases is the elimination of the removable piece near the chain sprocket. Some of the 85-86 had the extra lug to keep the cover from cracking at the rear locating pin. There is an air cooled four cycle cover with that extra lug probably 86.

I had an 1988 wr250 engine that I sold off the piston and cylinder, the rear of the skirt had a half moon cut out. A small cut out compared to the Italian 250 stuff I see pictures of on ebay. I can't see how skirt and powervalve would have any bearing on each other.

Fairly normal place for a 2 stroke piston to crack, probably there is casting reinforcement inside the piston that wants removing when new before use

Since the power valve is on the exhaust port, and the lower piston skirt has no bearing on the exhaust port, (it is only the piston crown that opens and closes the port) how could a power valve piston have any effect on power delivery unless the skirt on the intake side is different?
Does anyone have a power valve 250 piston and a non power valve piston to compare? Photos would be awesome! Especially the intake side of the respective pistons. I am curious just how different they are.

Well, Andy @ HVA got back to me and has a first over piston in stock for the non-power valve engine. I already placed my order!

Now I will need to send the cylinder out for boring as I don't know of any local shops to me. Any recommendations? Is Forest Stahl still around?