My wife has the 400 piped and clutched and I have a modded DS650. I have to be well into 3rd gear before I can even start to catch her. I actually have more fun on the 400, but the 650 gets me up the big sand dunes better.

 

The 400 motor with the right combination of parts can run with just about any quad made right now. I've got a pump gas race mod that can run with the best of them....the best part about having a hot modded 400 Polaris is the shock factor when you outrun or stay right with some of the newer 450's and banshees. Not many people know about how fast the 400's can be and it is so fun to watch their eyes after a race....it's really comical. Just ask CED on here how fast they can be.[img]i/expressions/face-icon-small-wink.gif[/img]

Modded 400 Drag Race Videos

 

not maybe the fastest quad on earth,but certainly one of the most powerful motor ever put maybe so,,,i mean over 75 hp with just a pipe and porting is a pure 2 stroke simply.
there is bigger cc's engine on the market that need some serious modifications to get that high numbers....
when you got the counter balance oil drained out,take a magnetic elements tool to see if there wear out dust
in it.

 

another possibility, is the skirt came off the piston and is wedged in the crank. mine did the same thing when it broke I could turn the flywheel a fraction of an inch back/forward but no more becuase the skirt would wedge between the crank and the case.

 

The skirt on the piston on my 95 Scrambler broke off and went down into the crankcase and punched a hole though the crankcase. The motor would barely turn over. I had to rebuild top, bottom end, and buy a new crankcase.

 

Yep - that's what happened to mine before I bought it. It was a baskets case when I got it.

 

broken skirt on stock cast iron jug ae the primilary problem on those mill,cauze we all known what it happen after of hours put on it,gasket are the same thing to always check time after rides,and heard a while back
stock oem gaskets was the most tough,,,,
i would suggest to send it to rick at RCR to hone that thing back to specs,boring the juf if needed to cast iron finish
specs and you'll not re-open it for while if take care of it sure then.