2011 800 Assault Cylinder/Piston/Top End

[mardimus]

This weekend I took my sled out of my trailer for a ride. I let it warm up for 8-10 minutes then started down the trail at around 25mph with an engine temp of 127 degrees. A mile down the road the sled shutdown and came to a complete stop. I tried to pull start it and would not even pull. First thought was maybe the clutch or pull start, but after opening the side, undoing the belt and removing the plugs I realized that the piston or engine was seized. I got the sled on a trailer and back in the garage. Removed the head to find the PTO side piston in bad shape. Rings looked seized or welded to the piston causing it to jam up. Was able to spin the engine by hand and remove the cylinders. Cylinders look a bit scrapped up or maybe ring material melted to the inside. Could be a combo of both. Anyhow, there is nothing broken on the cylinders. The ride before this one the engine was running pretty hot for long periods of time on an icy mountain side. I think that could have lead to this issue. Not too sure but seems to be the only issue as the other piston looked a little hot too. The oil was filled ride before last, coolant level was full. Spark plugs didn’t look white or over heated and seemed to be in descent shape. No aftermarket parts aside from maintenance.

Will plan to replace both pistons anyway and do a rebuild regardless. I mainly run the sled lower than 7K elevation here in WA state. The top end was rebuilt a couple years back by a local shop. I have a call into them to see if they can machine the cylinders. The last build they used SPI Pistons ( T-Moly Series, WPS-54-9279PS, 3.3420 Graf, 3.3410 Tip).

Cylinder # 3022205
Head #221401 or 5632373


So this is the help needed for this new project. After a lot of review on this forum researching pistons, aftermarket items, big bore kits, and upgrades I feel like there are a lot of options but found limited products online to purchase.

1. If you look at the pics, do you think I can hone the cylinders and just do a top end?
2. If I have to replace the cylinders which cylinder would you recommend?
3. Would you upgrade to a big bore kit like the RKT, Carl, etc?
4. If I leave it as an 800 which top end rebuild kit do you recommend?

Thank you for taking the time to review this project. I appreciate any comments, feedback or thoughts you may have.

Marty

Pics:

 

[ditch1000]

I’m in a similar boat...
Just picked up a 2014 Assault which appears to have a blown Mag piston... I’m really eyeing up the Bikeman Durability kit if I dont have to get a new cylinder...
If I need a cylinder; I’ll probably go with the Indy Dan kit...
Whats everyone’s thoughts on the Bikeman kit??

 

[mardimus]

I called Millennium Technologies about my cylinder. I was planning on sending it in to them but ended up swabbing it with Muriatic Acid and it cleaned it up right away. A bit of honing and it will be ready to roll. I may end up going with SPI as its all the dealers around me have at the moment. No OEM in stock and at this point I can just do a top end rebuild and get back at it. I am planning to adjust the oiler or will add oil with every fill up to make sure I break in correctly and have a little more oil running through out. Seems like most people do this with the 800 engines.
Super happy that I had muriatic acid on hand and that the gouges were only aluminum deposits baked to the inside of those walls. Got lucky I guess. will post a pic once I get i all cleaned up and honed out.

 

[ditch1000]

I’m just getting ready to fire up the new engine... New cylinder, pistons, fuel filter, doo oil cap and thermostat bypass..
I have heard that you can reset the break in mode on the sled so its easier to break in the new engine..
Is this correct??
If so, how do you reset it??