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I have a 2004 700efi, 4506 miles, looking for more power. if the Pistons, heads, and jugs are the same on the 700 and 800 (if), can I put an 800 crank in my 700 to get more ccs from the stroke??? If so, what else do I need... Cam, retune ecm, rods, ????
P.s. Anyone know what's involved in putting on NoS???
 

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Just my 2 cents worth....The crankshaft and pistons are not the same. I did not look up the jug. Needless to say, you are looking at a major project and expensive to boot. New crank about $500, plus pistons around $75 each, machine shop work. Then your ECM will have to be replaced....So far the manufacturers are keeping their information secret. Even though computer controls have been around for a while, I could not find an aftermarket code reader for any of my Polaris or motorcycle. My Bike is a harley, but nothing is available for any of the Motorcycle, ATV or Snowmobile manufacturers. So I would doubt you would be able to easily get the 700 ECM reprogrammed. I can see custom tune=$$$$$$$ if you can find someone to take on the project.

As for NOS, I would guess that it is possible, but it would be difficult to accomplish. ATV market would be small for anyone to make a kit, so you would have to source everything and make your own parts to get it to work. Then you still have the problem of tuning. NOS is an oxidizer...adds Oxygen to the intake so you still have to add extra fuel for the engine to burn or it will be lean and melt the pistons. Have to go with a wet plate style or source bigger injectors for the EFI. Same issue with sourcing parts and tuning to make it work. You would also have a high probability of breaking parts. NOS adds a lot of extra stress to the internals of an engine. Unless you went with custom made crank, pistons and rods, there will be failures there. Stock parts are not made for that kind of abuse

Don't get me wrong, anything is possible....in a local auto shop, I saw a Harley sportster with a roots style blower on it....If you have the time, money, expertise and patience you could get it all done.

With that said, I would guess that you would be farther ahead to spend the money on a complete 800 engine with the ECM to make it run. Then add whatever performance parts you can find for it to get what you want out of it. It would make an interesting project though.....grab a handful of throttle and smoke all four tires....
 

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Check out bp racing for the engine mods maybe they can also help with the retune
Good point, you might be able to do some upgrades to your existing motor to get more power at a more reasonable price that way!
 
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