250-500cc 2009 WR300 Refresh / Ice build

piston differences... I'm not sure the brand of the old piston but it does have a domed face. Any ideas what the old one is? The new one was a Wossner. What have you guys been using with good results?

Could be a wiseco, the flat top of wossner will change your compression ratio if it did fit, yes ask engine builder for correct wrist pin bearing as that should fit, does the piston fit in the cylnder as these should be matched.

I got wossner in my 360 but the pistons identical to original.

yeah the piston and cylinder fit great, and the cylinder and head were machined to match the new piston so I'll see what they have to say Monday. I can't wait to get it together!! I'm assuming the previous owner put the domed piston in.

yeah i wonder if the bike had the wrong piston in it? as far as wossner goes they seem to be very well made and a good buy. as stated above the wossners i have installed were identical in dimension to the originals, just lots of machining on the inside to lighten/balance

Have you actually weighed them side by side?
I didnt think that wossner was lighter but didnt have accurate scales to measure them.

You have to use a wossner wrist pin bearing if you use a wossner piston.

I have read some use the gas gas pistons in the 300's right? Could it be from that application?

Yamaha wrist pins work fine umm 18/22/22 i thinks the size very common item yz'ds use them and honda cr 250's all years as i recall. But i have been wrong before.

It looks like a wiseco piston to me.

My Vertex should be here today and then its assembly time. Anyone have jetting suggestions for temperature changes with the PWK carb? How many jet sizes do you usually go up for a given temp change at sea level? I'm a fuel injection guy not very good with carbs.

Have you looked into the lectron? They seem to do better with temp altitude changes than most carbs, plus you go from multiple jets to just a knob you turn if adjustment is needed.

Another person you should chat with for ice racing info is Cheyney engineering.

I was talking to him about swingarm shortening and he ice races 2 or 3 bmw g450x's so similar to our 449/511 platform, but he has tons of information and is really knowledgeable about bike setup. Not goign to help you with your specific question but if you have time to kill he is good conversation. Thought I would forward their info.

The bike looks great! Where are the graphics from and where can you get that fender in black?

Magiksc.com

Hey R. you should be looking at about 1 mainjet per 20 deg F change. Generally 3 sizes up on the main and one on the pilot is a safe place to start around here. I'd move the clip down one slot on the needle as well. Are you hitting any of the races around here?

One as in one number or one size? There is a 175 in there now for the main. I'm hoping to get the bike all together to ride here pretty soon. I have my TC449 all ready to rip for Ice. The 300 is just a fun bike to see if I can be as fast on a two stroke. Yes I'll do the Shoe 3hr and the 2hr this year. Maybe a few of the Cedar lake races if they allow Canadians. you?

Wossner on the left New Vertex on the right. Should be good to go since the head and cylinder were ported to match the Wossner. They are very similar.

Where did you get the black plastics and graphics from?

Magiksc.com he will get you everything you need

Since the moderator in the classified section appears to be on vacation for the last week I'll post here. 2 strokes are not for me and I'm sticking to my other bikes. If anyone wants parts form this bike it is being parted out. Let me know. Thanks Ryan