05 RMK 900

[ZB1988]

Ok dudes, first time poster long time reader. I’ve been working on this 05 rmk for a few months. I’ll try to sum up the backstory quickly but I fear it’s going to be a novel, but I bought this sled in the winter and rode it once. Flashed the egt probe at me. I shut it down and checked, sure enough previous owner had it disconnected. Connected the probe and carried about my ride. It was cold out. -20c. So it took a while to warm up. It was kinda funny in the low end with power cutting out but immediately ran great. Rode it for a couple hours. All seemed well. My buddy rode it the following day quickly with about the same results. Did a lot of research on the sled (a lot, I still do daily) so I thought tps or harness. I set up the tps to factory spec and proved it’s functional throughout its entire band with my oscilloscope. While I had it out, I probed the harness and found the signal to drop out. Groovy I thought. Bought a new pigtail and replaced it. I replaced the throttle and oil cable at this time. I noticed many repairs in the main harness at this time. And thought I solved my original issue. While I had the sled in the shop doing this work, I also installed the slp head I bought to use as well. I thought it would compliment the slp pipe and can quite well. Fueled it up with 50/50 ethanol free 91 and VPC11 with a little premix and installed new ngk plugs and a brand new egt probe for the hell of it. Sled was ready to go otherwise. And found I had very poor performance. Plugs looked very black and oily. While I had the head off I noticed the top end looked very poor. Piston skirts and cyl walls were notably worn. So I said ok and I went ahead and bought myself a new main harness and fuel filter and tested fuel pressure. All of which was ok. So then I went and bought myself a wrecked rmk with what I was told was a good running engine. Plugs looked nice when I pulled them and the top end was looking great. So I did the swap, installed the slp head on the second engine. And idled it on the stand to op temp to bleed coolant, revved it up a few times. Noticed a few spots of oil on the shop floor. Checked the plugs and sure enough they’re black and oily. I’m at a loss, the pump is set up and arm returns perfectly. Seems odd the same issue is happening on two engines. Any advice on where to go next with the diagnosis? This engine starts and idles just fine, as did the prior one. Perfect idle rpm.. I’m starting to think the Center seal is ironically blown on both engines...

 

[ZB1988]

I should add, I want to rule out the stator on engine 1, ohmed out perfect. I used engine 1s reeds in engine 2.Used engine 2s injector harness and ignition harness. They looked to be better. I also used engine 1s intake boots on engine 2 as they looked to be recently replaced and the ones on 2 were scorched. Exhaust valves functioned on both engines. I also know for a fact I did not starve either engine for oil. I bled it all perfectly. There was prior other electrical problems, shorts in the main harness from the bar riser pulling the harness into the rider select area, found this upon the third ride. And the 3x yellow connector was making poor contact. Repaired this and all electrical issues appeared to be resolved st this point. Good lights, added heated grips are working great. I wonder if the ECM took a hit from all that going on and it’s just running rich for some reason. Going to swap ecms and capacitors and tps. Will rule out every electrical component to me. Engine 1 had 110 psi on both sides at 3000ft. Top end was torched for sure. Lol. It’s getting closer though. Just thought I’d share my experience thus far and see if you all have some insight!

 

[94fordguy]

Looks like a good project! I'd fill the oil bottle full and see if the level drops, that would indicate a bad center seal. I'm not sure how much oil it would take to foul a plug, my sled is currently running 18:1 on oil... I've tried without success to lean it out on oil, I think the pump is just worn out and puking way too much oil into the engine, however it hasn't caused me any running issues yet so I've let it be. Good luck with your project, I'm just short of 6700 mountain miles on my 05 166 now!