I own a 96 Polaris Indy Ultra 680 triple, and it hasn’t been running for years. Its seized, so I wanted to rebuild it. I took it apart and took of the cylinders, but the pistons still won’t budge when I pull the starter? Is it a crankshaft problem?
You will need to do a full crankcase teardown, send the crank into Indy Specialities have them rebuild it, balance it and you will be good to go. I would also recommend sending in the cylinders to them and purchasing the pistons from them. They will match it all up perfectly like it is a brand new OEM engine. Or buy pistons and send them in with the cylinders. Either way contact them here, they are the best place to go for Polaris stuff!
Idk possible I guess, that is one thing I have never seen happen on a snowmobile. My 3 wheeler back in the day yeah because well Honda didn't exactly make it a priority item for some damn reason, was able to fix it as at the polaris dealership we sold quads and worked on customers honda's even though we were not a honda dealer. Shockingly the fix worked, icr what the mechanic did though to fix it.
Also I will say this about the Polaris Ultra engine...For a Triple they were really rock solid...Of course as long as you left the pipe OEM and didn't put Triple Pipes on it. Would cause issues of course in the crankcase causing them to crack or even worse shoot out a rod.
Hopefully he sends it into Indy Specialities and puts it back together.
Was there a busted piston skirt? Common issue, and a piece falls down into the crank and binds it up.
But, in the end you probably want to tear it completely down and rebuild. Not sure when Polaris fixed the oiling issue on those cranks, but there is a mod to get more oil to the PTO bearings.
Not sure if it is worth rebuilding the crank though. Depends on how much the sled is worth to you.
That crank issue wasn't on those Ultras iirc. Only the XLT engines. The ultra, the 600 XCR SP, the 700 and 800 all had a different crankshaft then the XLT's did. A much better crankshaft that held up really nice. And it was around 1995 or iirc they did that on the XLT mono block. These are all individual cylinders as well.
Also Indy Specialities does awesome work, next time check them out. Idk if Northern does the matchup with pistons & cylinders but if so nice, so does Indy. A lot of the local dealerships send their work to them as well.
Ten bucks says its the water pump. the seal leaks, causing the bearings rust and bind the motor. if your lucky it didnt leak tooo bad and rust the main crank bearings. if the motor is dry inside you could be in luck. pull the 10mm drain plugs under the manifold to check for anti freeze.