Hello to all, new to the forum-

I was sent here by a friend that said there was a wise man here with a wealth of knowledge-

The question is actually about the 700/800 polaris twins in general-

After years of running them in rangers, I'm having issues with the oil pressure relief valves sticking in the bore, causing a valve float issue on startup that it worse in cold weather. My fix so far has been to remove the piston out of the valve polish it and re-install. This works for awhile (have a video of it on youtube) Another polaris tech turned me on to installing an 8mm/5/16" ball bearing into the bore, followed by the spring and the piston re-installed on top, up side down. This provides about 20 more lbs of oil pressure than stock, but at idle on some machines i've worked on it seems to allow oil pressure to bleed off, followed by a lifter rattle- When checking with oil press gauge it shows about 5-10 psi. Give it a little bump in the throttle and oil pressure runs up there around 20-30 lbs for about 20-30 seconds at idle and then slowly bleeds off again. My polaris tech says he's done several of the 700/800s with this mod, most of them experience the lifter rattle, but none of them have failed because of it. As a mechanic myself, it makes me uneasy when something like oil pressure isn't where it should be.

I've had an engine or two out of a polaris Ranger, and forgot last time to take a look at the relief valve bore just to see how it's shaped inside and maybe why the ball bearing mod isn't working better. Some have told me I need to machine the bottom of the bore for a ball bearing so it can seat properly. I'm wondering about using a greased drill bit and lightly hitting the bottom of the bore and just see what happens.

My polaris tech friend believes the oil pressure bleed off issue has something to do with a port above the ball that isn't being blocked off like it normally would be by the piston.. he says putting the piston in on top upside down sometimes covers that port, sometimes not. I don't know if he's just giving me a line, or if this is the case.

This is highly experimental territory, but is an option I'd like to perfect since for many replacing the engine case just to replace the pressure relief valve bore is such a waste of time and money. I'm upset with polaris for such a design flaw of putting a steel piston into an aluminum bore, but what's done is done.

Looking for all the experience and insight I can get!

Thanks.

 

Makes me uneasy also as oil pressure at 5500 rpms should be a minimum of 35 psi with a normal reading of 39 psi according to the manual. Pressure should not be bleeding down or fluctuating that much.I don't like the tapered valve also,but experimenting with a ball bearing could do more damage. Granted some machines do have this ball bearing set up,but not in any Polaris machine.