Max bore size on a '85 R?

[Dammit!]

I can't find it. Must be having a blonde moment.

Stock is 66 point something mm but what is the max bore size before a cylinder has to be sleeved?

[Dammit!]

Come on now. Somebody has to know this.

[Jason Hall]

Dammit, I believe the biggest piston available Is .140 over for the 85-86. I think that Is 69.50mm. A 310 pro-x has a 72mm standard piston. You can buy up to 73mm for the pro-x cylinders with the short 85-86 connecting rod that makes 310cc with the stock stroke. I'm not posative on all this, but seem to recall a .140 from someone like Dave Moore racing.

[3Razors]

Correct..Rumor is though that Wiseco is going to be discontinuing some of the larger pistons piston sizes for the 250R.

[Dammit!]

I just took it to the shop around the corner and it needs a 6750 piston to clean it up completely. Not really sure what 6750 means but he said there's plenty more sizes left after that.

Hope that isn't true about Wiseco.

Edit: 67.5mm? I AM MAXIMUM SMART! :lol: :lol: :lol:

[Blown 331]

[QUOTE=Dammit!;653450]
Hope that isn't true about Wiseco.
QUOTE]

No kidding. WTF. Hard to believe the popularity of the 250R has dies down that much. Mines got a fresh bore and I have a standard spare cylinder and I dont ride it enough for this to affect me but it still sucks.

[Jason Hall]

Wiseco should discontinue the smaller sizes. With these engine's getting older, most people need the bigger size's. I like to run cast Pro-X pistons, but the biggest you can get are .040. I tried to get a .050 and couldn't I was way bummed out, as this .050 Is my best running everyday rider. Yours Is .060 Dammit.

[Blown 331]

Wiseco should discontinue the smaller sizes. With these engine's getting older, most people need the bigger size's. I like to run cast Pro-X pistons, but the biggest you can get are .040. I tried to get a .050 and couldn't I was way bummed out, as this .050 Is my best running everyday rider. Yours Is .060 Dammit.

Very good point on the bore sizes. I'm sure there has to be other companies out there making the larger sizes still.
What do you like about the cast pistons over forged? Don't you think the forged can take more piston slap with out breaking? Whats the price difference? I'm gonna pull the head on my 84 250R soon and I have a feeling it's on the stock piston and will need a bore so I might look into Pro X.

[KASEY]

NOOOOOOO i have 5 250r cylinders on the stock bore!!!!!

[Mosh]

Wiseco should discontinue the smaller sizes. With these engine's getting older, most people need the bigger size's. I like to run cast Pro-X pistons, but the biggest you can get are .040. I tried to get a .050 and couldn't I was way bummed out, as this .050 Is my best running everyday rider. Yours Is .060 Dammit.

This why smart people should run companies.Excellent point Mr Hall.

I tell ya,the richer people get,the dumber thier decsions.I think they sell their common sense off,to get more money:lol:

[Jason Hall]

I like cast pistons because they are not a hard as a forged piston. If you have a problem with a forged 2 stroke piston It's almost certain you will have to bore the cylinder. With a cast piston you have a much better chance to just hone the cylinder and run It again on the same bore. Has anyone ever seen what happens when a wiseco ring hangs In the exhaust port? Well It usually takes 2 bores (somtimes more) to make the cylinder usable again. A cast ring can snap off and not do as much damage. I'm not saying that a cast piston Is better for every application. I just like them because I HATE to bore the crap out of my cylinders.

Kasey, I hear you 100%, I still have a couple cylinders on the first bore's. I also have extra Pro-X pistons to replace them :Bounce

Mosh, the people that are In charge of discontinuing these parts obviously don't care about keeping an old machine running :beer

[Yamatrike400]

I was at Haydays Snowmobile grass drags last weekend and i stopped by the Wiseco booth and asked the guys if they had stuff for the ATC250r and they said that the pistons,etc were a pretty popular item?