1972-75 engine, big bore 88mm?

Some more numbers for the mystery piston: 87,92 mm. No hit googling it.. Any ideas? (scratches are someone elses bad work..)

Maybe a KTM or Maico piston.....

Late 70's (prior to the reed engines) Maico 490's currently have a 87.92 size available (Wossner).

Still looking for a Mahle 87.92.

If the piston was meant for another brand someone did a great job milling the transfer port.

Cool, thanks! I agree that the port looks very well made. My friend took the piston off yesterday and noticed the needle bearing was shot.
Didn't look as the pin or rod was damaged but he'll try with a good pin and bearing so might be able to get it together and running again.

Might be time to contact the Husqvarna Museum:

www.husqvarnamuseum.se


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Might be able to trace engine back a few owners. See if we find out something interesting!

I thought the Husqvarna Museum would only have knowledge of the original owner unless it was a team bike. It could be a former assignment to a sponsored rider.

Well, it's wasn't Arne Kring at least.. I asked him and he'd never heard of a 88 mm piston for that type engine.

Would the rider know the piston size?

I think Arne would. He's been selling Husky parts out of his shop since way back.
But the porting on this cylinder looks so rough and the liner hasn't had the edges of the ports smoothed much.
I'd think if it was a factory job they'd at least made that effort.

Hi there. Out of interest what is the size of the wrist pin /gudgeon pin in that piston? The 73 450 I had was a 20mm and 450 replacement rod kits are very hard to get hold of!! Did try many Japanese rod kits but these had a 18mm wristpin

Hi! Outer diam. is 19,92 mm, inner 13, length 70,75.

When I was looking for a 430 cylinder on eBay a seller said the bore size was 96mm. It had to be a typo or he measured the OD of the sleeve

Krudd, What ever happen to this motor? Was any effort made to put it in a frame and get it running or is it a boat anchor now?

Nope, not a boat anchor! As I wrote in the first post, my buddy bought a lot of Husky parts and the 500 was part of the deal.
But there was also a 360 R/T without a complete engine. So now he is working towards getting the R/T together in near stock nick
but plans to use this 500cc engine in it. I've been helping to search for parts and found some hard to get R/T-items so this bike will
most likely get finished first of the 7-8 bikes that he bought, all as basket cases! I'll post up more info when it's start-up time.
Next is a mock up and get the engine in the frame to remake some brackets that have been hacked off. Also the rear frame loop.
The 360 R/T turns out Husky produced as a 250 R/T and checks have ensured it isn't stolen so a road registration will hopefully follow too.

Thats interesting seeing that the 360RT uses the same center cases as the 450. Do you think the 500 may have been built from the RT motor?

No that's one of the few things we are sure of, the 360R/T parts and the 6-7 other Huskies came from different sellers (i.e. previous-previous owner).

There was a giant Gurtner carb on the 500cc engine. Do you think it would be ok to use a 38mm Mikuni instead?

Properly jetted I don't see why not, it will probably be even better. Stock on the 76 360WR the Gurtner didn't go over very well in the US.

This Gurtner has been modified with a grinder inside, but there was also a box full of ok Mikuni's 38's in the deal so..