While prepping my sled for summer storage this past spring, I found that my ’04 Polaris 800 XC SP (with the stainless steel power valve mod, both cylinders) had stripped all the treads from the top hat nut that attaches the power valve to the bellows. The valves still moved freely within the cylinders and its threads were like brand new. This happened to both cylinders. Luckily all the metal shavings were contained within the valve body and bellows. As I recall during the winter, I had just put 400 or 500 miles on the machine when I couldn’t get it to go over 7200 RPM. Since I was on a long trip (another 400 miles to ride) I couldn’t trouble shoot it until I got home. My questions are: Is there a different, stronger nut for the Stainless Steel valves? Something made out of Stainless Steel? Does the extra weight of the valve require different bellows, springs? Anybody else having this problem?
West Bloomfield, MI
Over the years as the engine performance and calibration of the Liberty 800 big block changed, the amount of heat the valves were exposed to also increased. This is more of an issue on the 800s than the smaller engines (like the 700) due to the larger bore of the 800, resulting in less room for coolant flow around the valve area on the 800.
In 2003, Polaris was using aluminum valves. In 2004, they upgraded to â€œhard coat anodizedâ€ valves, followed by stainless steel valves in 2005. All of these valves now supersede to the â€œStainless Steel Valve Kitâ€ (Polaris part #2202838). This kit contains the #5134492 stainless steel exhaust valves and valve springs (kit instructions provide information on what springs to use for what elevation).
Titanium valves were released as an accessory for MY05 for the 800, but with the success of the stainless steel valves the titanium accessories have since been dropped from the line.
Polaris went to the Stainless Steel valves in MY05 on the 800 using the aluminum cap nut, with Loctite 242 applied to the cap nut. When properly cleaned, Loctite applied and torque to 16 ft./lbs., the valves are secure. If they were contaminated with any oily substance, the locking agent would not bond (this applies to any fastener when using any Loctite bonding agent). The threads of valve and cap should be cleaned with a Loctite primer â€œNâ€ and then have Loctite applied.
The cap nuts have transitioned from aluminum to anodized aluminum (Polaris part #5631687). In MY06 all valves were installed with the anodized cap nut and Loctite 242.
For the absolute best retention of the cap nut when using stainless or titanium valves, you could use Loctite 2760 (Polaris Part #8560107). The torque specification for both stainless steel and titanium is 16 ft./lbs. (+/- 2). When this Loctite 2760 is applied, a heat gun will have to be used to remove the cap nut. The use of 2760 Loctite on aluminum valves with aluminum cap nuts is acceptable. However, the nut will have to be heated to 350 degrees prior to attempting to remove it from the valve stem. The torque specification for aluminum valves with the old aluminum cap nuts is 12 ft./lbs. (+/- 2)
Polaris also wanted us to remind customers that they should always use high quality 2- stroke oils designed for variable exhaust valve engines. In the Polaris Service manual it is recommended to clean the valves every 1000 and 2000 miles, as well as preseason. Appropriately servicing a heavily carboned valve will minimize the chances for valve damage.
Also, the vehicle Owners Manual for 2003, page 125, states the customer should take it to his dealer for cleaning and servicing, as well as mentioning the use of proper oils.