250-500cc Squish Clearance Wr360 '93

Hey guys,

Just a quick question for the rebuild I am working on regarding my 1993 WR360. The Engine was a mess and through quite some extensive work I am almost finished with it.

I had a shop fit a new Samarin drive shaft and in combination with a new Wösner piston I just came to the task of measuring the squish clearance for this engine. I have fitted the piston (without rings) cylinder (new plated) and head with a 0,4mm base gasked and no head gasked O-rings.
Using the solder wire method I've measured the squish which can down to 1,6 mm. I've found some Husqvarna original specs which state that it should be 2,6mm for the 360. This however seems quite a lot, especially since this would indicate that I should use a total of 1,4mm base gasked.
Can Anyone confirm this value?
I use this bike for local woods riding and also for street supermoto. Durabilty and lifespan are more important than pure performance.

Ps. I also noticed that the piston skirt just barely touches the crank. I am planning on removing just a tiny bit of material from the piston to resolve this. Has anyone else had this problem before?

Kind regards,
Thomas

Would it not be better/easier to remove material from the piston skirt?

Does your piston have the wrong deck height ? Or is the con rod 1 mm too short?

Sorry, this is also what I meant. Adjusted it in the initial post.

The machine shop kept the con rod, but maybe I'll give them a call to ask about it. I will also take a look at the difference between the pistons. I expected it to be a easy plug and play process.

soooooooooo
the 360 connecting rod at this point in time is like finding a unicorn in your backyard
the KTM 360 will work but the 2 things to know are the 360 used 2 different length rods over time 132 and 135mm from memory, also the big end pin is shorter on the KTM
the pin isn't the problem you can preset back together and ignore the pin being in the plates a bit, but,,, if you have the 132 or to put it better the 3mm shorter rod, you will need to correct that
don't butcher the piston, it will affect your port timing

I called the machine shop yesterday. According to the manufacturers parts numbers both the conrod and the crank should be correct. The Samarin conrod is 135mm exactly the same as the worn out original Husqvarna that came out. They have never seen this problem before with this generation of Husky's.
I also took a look at the difference between the new and the old piston. They seem to be both manufactured by Wössner, and differences are almost non existant, wall thickness seems to be a little different at some spots. Both the deck height and skirt length are exactly the same.
I also noticed that the old piston has some dents at the same location where the new one hits the crank, so this problem also existed when a previous owner rebuild the engine.


New and old piston.



Left picture is the dents in the old piston. The right one is the new piston. I was able to push it through B.D.C. with only a slight amount of force. Still I am keen to take about 0,5mm off with a small file to compensate for play when the big-end and small-end wears in and get more play.


I don't think it will create any problems taking a slight amount of material of the piston as it will be far from butchering it. I am however keen to know where the problem lies. It could be that my bike has a slightly different crank than those of other manufacturing years.

I might try to get in contact with Wössner to see if they have ever seen this problem occur before.

These are 2 old pictures of my '93 360 crank on the smaller '92 250 cases. Maybe someone recognizes the crank as being a different from other model years?


And a small teaser on how the engine is going to turn out.

Rods for the 360 are available from Royal Rods about 130.00 dollars and look like good quality.

.050-.055 squish.