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Discussion Starter · #1 ·
So I am thinking about building a serious XCR motor for lake and grass duty and had some questions about part dimensions. I have both 700 and 800 cylinders at my disposal to use. I was going to bore out the 700's to 800 size with max effort porting, reflash, high rpm pipes and the like. by all accounts 225-230hp should be within reach. Of course it is always a cost/ benefit analysis as I do not have unlimited money. The other option I was exploring was stroking the crank to 70mm and trying to use the stock 700 jugs, but this only nets 750cc's so I would be leaving a fair amount of power on the table. I ran the numbers and a 70mm bore would still leave plenty of cylinder thickness at the tails and produce an 808cc combo which is legal in pro stock, mod and some others for 800 class racing. It would be 70x70 and the cylinders lend themselves well to this because the transfer and boost ports are lower. Small shim and everything works. Back in the day people would bore out a storm and use skidoo mxz 583 pistons right off the shelf.

QUESTION: Does anybody know of ANY two stroke that had a bore of 70mm and a stroke of 70mm with the appropriate compression height and pin diameter, Ring locating pin clocking ?? I called wiesco and asked if I could give him dimensions and if anything on the shelf or catalog matched, the computer would spit out a part #, and he said it doesn't work like that.

So if anybody out there has done this or something similar, could you throw me a few crumbs of info, dimensions, part #'s or the like?
 

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I dont know exact details but I think it has been done before for prostock race motors.
Dean Schroder, phil stanley, Iantommassi, Doug Flannery are some race engine builders that may still be able to build one or source parts. Those are the guys I would call first, add the crank shop to the list as well.
 

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Im going to throw this out there.If cost is at all a concern just go buy a turnkey sled.You”ll spend far more time and money building one.
On a side note I did run 583 pistons in an xcr 800 engine but you oring surface is gone so I had copper head gaskets made and custom heads.
 

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Decker Race ported 96 Ultra SP drag build
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The stroker 700s to run 800 classes are commonplace nowadays. Call up Iantomasi over in Ontario, they have tons of record sleds to back up their claims. Coupled with Jaws HR series race pipes you'll have easily 230-240, if not more, horsepower.
 
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