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Just joined and looking for 800HO build advice

DoggerCDN

New Member
Messages
6
Age
59
Location
Ontario, Canada
Country
Canada
Years Snowmobiling
48
Snowmobile
2015 Polaris Pro-X 800HO
2006 Polaris Fusion 600 Dragon
2003 Polaris Edge X 600
1999 Polaris Indy 700XCSP
1991 Polaris RXL
Hi guys. After 40+ yr of sledding (32 on Polaris) but only being a casual sledder the last 5 or 6yr due to business (own auto and leisure sports repair facility) and life, it's time to return to being a hardcore sledder.

Just bought a new to me 2015 Polaris AXYS Pro-X 800HO with 4200mi, looks and maintained like new, but has blown PTO piston, and scored cylinder. Previous owner had engine built by "this great race shop" because someone told him 800HO's ate pistons every 3000mi. This "great race shop" put in a new crank, and durability kit but neglected to clean power valves, replace cracked intake boot, and then neglected to tell owner that ecu should be reset by dealer to break-in settings. Needless to say. 400mi later, I now own a great sled for half the price comparable sleds are selling for.

I have always had best luck with any "projects" I buy when I completely disassemble them and then reassemble them to better than factory standards, and this is how the Pro-X will be done. Expect to hear from me a lot in the coming months
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My asking for opinions and information today is concerning the 800HO engine and its supposed shortfalls. I want my motor strong, but my main objective is bulletproof, and over the next while I will be asking for opinions on the ongoing build. The main issues I have researched seem to be engine running too hot, and piston skirts collapsing. Engines running too hot can promote piston skirt collapse, so some remedies may overlap I think.

To address the hot running I picked up a 2019 800HO cylinder head, cover, and newest version thermostat as this seemed like cleanest approach without external thermostats. Is there anything better?

First question is :When I changed my 06 Fusion 600 from two parallel systems to single series system my temperatures dropped from 130 average to 105-110 average on normal conditions. Has anybody tried replumbing cooling system to run in one series circuit rather than two parallel systems AXYS seems to run from factory?

Second question is : Has anybody used Swaintech ceramic coating on piston crowns and cylinder head? We use it a lot in musclecar motors to help with detonation and lowering engine temps. My direction of thinking in the 800 is twofold. Ceramic coating of crown, combustion chamber, and exhaust port would reduce heat transferred to engine castings by sending combustion heat out through exhaust (which will also be ceramic coated) hopefully lowering engine operating temperature. Coating of piston crown should also reduce amount of heat transferred to pistons / pins / bearings / rods helping with piston skirt expansion / contraction issues.

I already have Wossner durability kit, so I guess that's what I'll be running although I like RKTek's approach better. Pistons come pre-coated with a red skirt coating, but the 400mi pistons already had a lot missing, so that brings another question.

Third question is : Has anybody used abradable piston coatings from Line2Line, US Chrome or Swaintech? I know they work in muscle engines, superchargers, and marine engines but how about sleds. Since they go in with a slight push fit and then wear down coating through repeated heat cycles until they form custom fit and ideal oil film barrier for each cylinder, it seems like a win/win. The piston skirt slop is reduced due to less piston rocking and better lubrication. Less friction also means more freely running engine and less internal heat generated, again helping keep temperatures down. Since most cooling below the piston rings on a two stroke engine is performed by the fuel and oil mix, I figure any help reducing friction and temperatures below rings is important in today's engine with fuel only introduced in transfer ports, and EPA mandated minimum oil injected into case.

Any info or experience on these issues is appreciated. Sorry for long post. Thanks in advance folks!
 
Saw you already got some responses to this over on HCS, much of the same guys posting on here that already responded over there. I agree on forgetting the durability kits and going with the newest stock pistons.
The head upgrade should fix the warm running issue as it allows more coolant flow than the stock 15 head. One caution still is the thermostats still seem to be failing at a pretty good rate, I think the motor is rattling them apart or causing them to stick, which is why all the newer designs (850 & 650) have them in the coolant bottle now.
As far as the coatings, seems they fell out of favor as most pistons come with some kind of coating these days and there were some shops out there doing less than stellar jobs over the years. That said, I know Swain does work for many industrial and OEM manufacturers, I've been to their shop years ago as part of a previous job. Worth trying in my opinion since you have experience with their product and they are one of the high end shops in my mind.
 


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