XP overheat then rpm problems

[Jetjock]

I installed a new dynoport pipe, Y, and silencer, a 13-1 chuckaroo head, and a roosterbuilt clutch kit on my 2009 XP 800 -163. Took it out and for the first 10 easy miles it ran great, tached right at 8200 at full thottle, and there were no adverse engine indications (knock sensors/overheat lights, etc.) The conditions were firm and after walking up and down several steep grades the overheat light illuminated and the rpms dropped off at WOT. I shut it down and packed snow on the exchangers until it was cool then started it up and verifying that the overheat light was out rode the trails to the truck. The sled ran fine excepting it would not tach more than 7800 rpm for the rest of the ride -it would accelerate rapidly then fluxuate around 7800 with a reduction in power (the knock display and other lights did not indicate any problems.) It is not using any coolant and other than the overheat light there weren't any signs that is was hot. I was running 94 octane oxygenated fuel that was purchased 3 months ago.

I have checked the compression (at sea level) and it is even at 164 lbs both sides using the electric starter (156 lbs cranking by hand) both of which were done with the throttle wide open switching between 3 different compression testors, the plugs are a nice dark brown (both electrode and insulator), the primary clutch was removed and the rollers, ramps, etc are all in perfect order, the secondary clutch was inspected and the rollers are all intact. I also removed and verified the DPM selenoid is operating correctly. I just now retarded the timing 1 degree to hedge against deto from the higher compression head.

I have a friend that has access to a $10,000 fuel tester which we'll use to verify the octane and other fuel related #s are correct. It won't be back in the state for a couple weeks -patience.

Suggestions?

 

[winter brew]

Has it had the limp-mode update done? If it goes into limp-mode as yours did when it overheated, some '09's would remain in this mode until reset by the dealers BUDS system. There is a update so this is no longer necessary. I will get you the # of the update later when I get to the shop, or do a search on here.....Big John has posted it before.
They need ice-scratchers for sure in this snow we have right now.

 

[71Dragtruck]

Limp mode update #415-129-450

 

[Jetjock]

I had the limp mode update done 2 months ago. When I had the timing retarded 1 degree I checked for faults. The only fault showing was "overheat" and it was reset.

 

[caper11]

Was the snow conditions low enough to cause a overheat situation?, do you have a temp gauge? what altitude were you riding at? Are you sure that is a 13.1 head, your compression sounds high to me 125psi is stock at 3500 ft, I can't remember the comp ratio I think it's around 12 to 1.


When i put my engine tech stat housing in it took me a long time to get all the air out of the system I even ran the sled up on my sled deck ramps to get the nose of the sled as high as possible, and could still hear the air gurgling in the system

 

[Jetjock]

Stock compression is supposed to be 12.3-1 and at sea level shows 154 psi using the electric start and 148 pulling it over by hand. The head I installed is a 12.9-1 and shows 164 psi with the electric start and 156 by hand. I noticed that the coolant level dropped slightly during the ride but assumed that there were a few bubbles in the system -it has not dropped since and holds pressure. The engine ran strong until it got hot and then pulsed on the top end for the 10 miles to the truck -maybe it was still hot enough to limp the timing (I thought it would give either a knock or overheat message if it was doing so?)

I do not have a temperature gauge and yes the snow conditions were firm and icy (I have ordered cable scratchers.) Maybe a temp gauge would help anticipate overheat problems -I am sure it is nothing spending more money won't fix, right?