2013 RMK Pro topend/compression/coolant/arrrrrr

SRXSRULE · Dec 16, 2016

Pistons look good for used pistons, no scoring going on. You do need to look closely at the rings and see if they are flaking.
To get the coolant out you have several options.... One of the hand or air operated mighty vacs are a great tool to have in the shop (service diffs, Transfer cases, chain cases, do brake flushes, suck coolant out of radiators...) Or if its a 1 time deal you can use a turkey baster, or reduce down a small piece of hose to go on a shop vac. Eric

tuneman · Dec 16, 2016

Pistons look fine. Put the new ones in an ride it.

If you ever take the engine apart again, (hopefully not, since errors are more likely the more you take it apart) remove the two bolts at the thermostat and stick the hose/housing end into a bucket. Then take out the thermostat and use a clean shop vac to blow air into the engine. It'll blow all of your coolant into the bucket. In your case, unfortunately, suck out what you can and mop up the rest with rags/towels. Ya gotta get it all out.

Make certain to follow the instructions to the T. Rings word side up, aligned correctly with the ring pins, lube pistons/bearings with 2-cycle oil as you put them in, make certain the injector o-rings are there and seated correctly, you must use a torque wrench on all bolts(aluminum is finicky), and premix your first tank of gas at 50:1.

rydningen · Dec 16, 2016

Also, make sure the ring end gap is set to spec on the pistons, could save you alot of problems if they sre to tight out of the box.

omernikski · Dec 16, 2016

It's a sign....BIG BORE TIME!

Scott · Dec 16, 2016

omernikski said:
It's a sign....BIG BORE TIME!

Turbotater's 910 is a REALLY nice way to go. It's in the $2800ish range. Call him for a quote. It's a sleeved top-end kit that does require case porting.
It utilized the stock head cover, so it really just looks like you have cheater heads and that's it.
You can do a pipe mod and run the stocker, or he's got an aftermarket pipe recommendation also.

He's in Hazelton, Idaho.
He's also got a stroker 962 that he does with Jadd at Stroker Customs in Colorado.
He's REALLY picky with his tolerances and knows a TON about porting and cylinder carving.

Look him up on FB at T8rz Porting and Performance or here on SW as Turbotater.

Most people don't know this, but MANY other shops send their stuff to him to port cylinders to their specs.
BUT when you send it to him directly, you get HIS specs.

He doesn't advertise. His business is almost strictly word of mouth.
Wayde is the man!!! Search him up, his reputation speaks for itself.
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Bomontana · Dec 19, 2016

Finished...I hope

Got it all put together and went for a ride today. About 30 miles of thumb killing to get it broke in right. Here's my steps/advice for anyone who might want it:

Steps
-got a syringe/suction thing from autozone for $14.99 and sucked all the coolant out of the crank case
-once all cleaned out, fill the crank case with VES gold oil. About 1.5 quarts. Read this in a article where a guy was installing a fix kit. The idea is that it displaces any risidual water and lubes the crank up.
-clean and air dry syringe with brake cleaner, then suck oil out of crank case. Rotate engine, wait a couple minutes then suck out he remaining oil.
-take cylinders inside and check ring gap. #1 was a thicker ring with a tighter (.3-.4 mm) end gap. #2 ring was thinner with a looser (.4-.5mm) end gap. Two of my rings had to be filed down. I used a flat file, then a finer triangle file to clean it up after i got them right. Didn't want any burrs scoring up my cylinders
-for security, I packed a bunch of blue shop towels around the connecting rods in the crank case, this way no circ clip would drop down in there during reassembly.
-using 2 stroke oil as a lubricant, I slid the rings on the pistons and inserted each inside circ clip. My pistons had arrows which i was directed to point towards the exhaust.
-put rollers in connecting rod (lube), piston over rod, slide wrist pin (lube), insert outside circ clip (eye protection, they have a tendency to fly out right when your face is up on them, don't ask how i know)
-now, the directions for my piston set said have circ clip openings at 12 or 6 o clock. I've read 3 and 9 also, but followed the directions on my kit, each piston had one at 12 and one at 6
-install base gasket, and PTO power valve (loctite). Have PTO piston slight higher than MAG. with a sharpie, i marked where my locating pins were on the top of the piston, this helped me know where the ring gap should be and made compressing the ring easier. Lube cylinder and piston, and work the piston into the cylinder paying close attention to where the pin is. It took a while, but I was trying to be extra careful.
-fuel rail. I went to my dealer and got new injector o rings as they did not come with my kit. $6=easy piece of mind
-once cylinders are on, I put four bolts in the cylinder to line the gasket up then tightened them by hand and rechecked that the base gasket lined up well. Inserted the rest then started torqueing, working from the middle out.
-install head gasket and head o rings. I used just a dab of assembly lube to hold them in place. I've heard these o rings are quite crucial to get right.
-install cover gasket and spark plug o rings. Loctite and torque head bolts.
-reinstall water pump with new gasket
-install thermostat (I tested mine in a kitchen pan with water heated to 140 to make sure it worked before installing it) with new gasket and the bridge in line with bolts
-reconnect lower coolant line and fill cylinder through thermostat. Re install housing (loctite)
-reinstall knock sensor (check torque specs, manual seemed pretty adament)
-reinstall temp sensor. I used plumbers tape on that fitting
-MAG side power valve (loctite)
-reconnect oil tank (picked up skidoo cap $15)
-reinstall overstructure, pipe and can (almost forgot little square rubber bumper on bottom of pipe)
-jack up right side (MAG) of sled and fill coolant through reservoir
-get a metal coat hanger and put it around the oil pump injector that works with your throttle.
-first start. Once running, I pulled up on the hanger to open the injector fully which bleeds the oil line coming from the tank. Did this for about 2 minutes.
-remove coolant cap, let sled get up to temp and have coolant ready to fill reservoir once the thermostat opens. I did this all while it was jacked up on its side. Supposed to help get rid of air trapped in the system
-I had a full tank of straight gas. First tank on new top end is supposed to be 50:1, so I added 28oz of VES. 11x128/50=28.16
-ran it today, 1/4 throttle burps up trail for 5 minutes, 1/2 throttle burps for 5 minutes, 3/4 burps for 5 minutes...then i just rode it like it meant to be. We have about 3' of bottomless powder so it was a pretty good work out. Power got better as the miles ticked away.

Advice
-clean shop. I'm not that clean and in turn i kicked over brake cleaners, oil tanks, coolant bottles and beer cans. It sucks.
-take off overstructure, oil tank, clutch guard, secondary and upper air box. It made things easier for me
-have a helper for the marrying of the cylinders to the crank case. Just don't let him rotate the primary without telling you. That hurts fingers
-I bought a 1/4 drive ratchet and socket set for $20. It's nice, I don't care how un-manly the auto parts store greasers think it is
-find the service manual. Torque specs and other random tips can be found here faster than posting on forums

One more ride tomorrow to decide how worthy my first top end, or any work on a snowmobile really panned out. So far, it seems good. 122 degrees on the trail for 7 miles straight tonight made me feel pretty good.

if anyone wants to correct me on anything i did, by all means do it! You guys got me beat by a mile on this stuff.

Thanks!

geo · Dec 22, 2016

That's the spirit. Who needs new and a warranty anyway.

sierraclimber · Jan 13, 2017

If this thread gets indexed for top end rebuilding I thought it would be good to add one tip. I finished installing the Bikeman durability kit and it is making a lot more power than ever.
I noticed the oil tank was draining much faster than usual on my break in ride.
Turns out I assembled the oil pump linkage to the carbs wrong. The oil pump arm is spring loaded and easily turns so that it is facing out board instead of inboard during reassembly. This will hold the oil pump wide open even though the linkage is working. Most people will catch it is in the wrong position when the linkage to the carbs does not spring back when testing the action.
Luckily no harm done but I had to tear down and reassemble it again after realizing my mistake.
Also a quick way to burp all the air out of the coolant system when refilling is to lay the sled over on either side briefly while running.

resent:

8emup · Jan 19, 2017

Dealer just tested the compression on my 2012 pro. The shop is probably around 5000ft both sides tested at 100. He said it's getting weak but run it until spring. If I'm keeping the machine they don't want to put a top end in until we pull the motor and send it out to have the crank rebuilt. They said they've seen way more cranks go than top end's. The sled has 1300 miles and is in perfect shape other than that so hoping it holds together to until spring. We will rebuild the motor and keep it in the family.

Bomontana · Jan 29, 2017

This would happen

Going up a trail for 4 miles and a ring blew apart tearing the engine to pieces. Jugs, head, piston, crank, crankcase, most likely reeds.... you name it. I figure I'm at about $3k for a new engine. Any ideas what i can do from here? Only got about 250 miles on the top end. Ran great, proper break in, let it warm to 100 every time. Anyone have an extra engine laying around? My buddy smacked a rock with his etec this weekend, considering a pootec.

Carnage!
Last pic is my remaining piston for possible diagnosis