Non Stock pistons in an RKT head?

[FNG]

I have a new to me 06 REV 800 adrenalin 151 with an RKT head on it, I don't know if they previous owner did just a piston drop in and head, or a bore kit. Called the folks at RKT and they said there is now way to know without pulling the head. I'm ok with whatever is in there so I'll get to that job when it's time but the former owner also was running NGK BR9EYA plags in it and stock should be NGK BR9ECS. Both plugs ar in the same temp range but the center pin on the BR9EYA is about 1/16 longer and so has more surface area exposed in the chamber as well as sticking farther into the compression chamber. I did call RKT about this but so far they haven't responded back so 'm throwing it out to the masses.

I'll probubly just go back to stock plags but just wonderin why this would have been don, I mean the guy had 3 sets of these non stock plugs in the seat so obviously it wasn't just a "I'll use these from my buddy and they will get me the heck outa hear" kind of thing, I have called the previous owner but so far he hasn't responded.

Thanks for your toughts

 

[High Voltage]

RK Tek 734/827 Big Bore and 82mm “Drop In” Piston Installation

1. Clean ALL new and old parts thoroughly with soapy water to assure no foreign debris is present
2. Set piston ring end gap between .016” and .018”. If larger then leave it alone.
To set end gap:
a) Place 1 ring in cylinder
b) Level ring in cylinder by using the piston as a leveling device. Measure gap with a feeler gauge.
c) Using a wet-stone or something similar, gently grind on one end of the ring until desired
clearance is obtained
d) Repeat process for each ring.
e) MAKE SURE you know which rings are gapped for which cylinders!
3. Install rings on pistons
4. Install pistons and top end bearing onto connecting rods. If you are using DOO factory cage-less bearings…DO NOT install piston cir-clips on piston until AFTER the piston is on the rod.
5. Install wrist pin and cir-clips onto piston. MAKE SURE cir-clips are full seated in groove!
6. Install, RKT supplied, .5mm gasket, base gasket. To assure a flat seal. MAKE SURE case and cylinder base is free of ANY grease or foreign debris. USING NO SEALER!! Install MAG cylinder. Hand-tighten bolts. Make sure the gasket has not been displaced during cylinder installation.
7. Install PTO cylinder using the same cautions as above.
8. Install RAVE gaskets (not supplied) under each RAVE guillotine. Make sure RAVE base housing has exhaust supply hole line up with supply hole on cylinder. Bleed hole toward belly-pan.
9. Torque cylinder bolts to 27 ft/lbs and then final torque bolts to 32ft/lbs.
10. Install Head as per supplied instructions. Torque @ 22ft/lbs
11. Do not run the BR9ECS plug run the BR9EYA plugs (Arctic Cat) or BR9ESà gap the plug @.020”
12. PREMIX a 150:1 oil ratio in 1st tank of fuel. RKT recommends to always premix at 150:1 in addition to your oil injection system. DO NOT USE AMSOIL!! Break in engine with mineral based oil for the 1st 100 miles.
13. IMPORTANT: DO NOT USE ANY aftermarket silencer on this set-up. Use the stock pipe and muffler. This “kit” was not tested with any other pipe/silencer combination.
14. Fire engine and check for base gasket leakage. Make sure there are no air pockets in the coolant system.
15. Run engine at varying throttle positions for the 1st 50 miles checking piston wash and plug color (and adjusting accordingly), then ride it like normal! NOTE: The 800 and 827 engine are 8400-8500rpm engines! 734 kit runs at 8000rpm. NOTE:These engines take 100 miles for the rings to fully seat.

16. Jetting (734 kit):à> on the Flat-Side carbs, start with 370 mains, 20/17.5 pilots and the needle from the 500SS carbs.. Round Slide:->> 310 mains, 40 pilots, stock needle. NOTE: These are JUST starting recommendations…FINAL jetting could be much different (usually MUCH lower)
17. Jetting (827 kit):à If you have hooded needles (SOME ‘03 and newer) start with 390 mains and work down from there (probably end up at 350’s) richen needle 1 clip. For ‘01 and ‘02 , non hooded carbs, start with 480 mains and work down.
18. Jetting 82mm drop in :à If you have hooded needles (04 (Some 03 models) and newer) start with 370 mains and work down from there (probably end up at 350’s) richen needle 1 clip position. For ‘01 and ‘02 , non hooded carbs, start with 490 mains and work down and add extra shim under needle.
800R engine: 450 main jet and raise needle 1 clip.

19. Clutching: RKT recommends changing the primary spring to the Ski Doo Purple-Purple Spring.
If below 3000ft fully load the pins and set clicker to #2 setting. If above 3000ft-> start with 18grams of pin weight. Run the engine ON SNOW under load and adjust pin weight until the engine is pulling 8000-8300rpms (800 and 827)..then click up 1-2 settings on your primary(#3 or #4) and you should be close. NOTE: do NOT assume that if you are pulling the 8400-8500 rpms that you have the correct LOAD on the engine… ALWAYS load the engine UNTIL it will no longer pull the 8400-8500 rpms then you will be in the correct area for clutching. Do the same for 734 kit but rpm is 8000 vs. 8500

 

[High Voltage]

11. Do not run the BR9ECS plug run the BR9EYA plugs (Arctic Cat) or BR9ESà gap the plug @.020”

 

[Antsa]

11. Do not run the BR9ECS plug run the BR9EYA plugs (Arctic Cat) or BR9ESà gap the plug @.020”

Is there a reason for that?


Easier to check jetting from plug?

 

[tigerdog]

rkt

sounds likke drop in kit, i would follow kelsey,s instructions.

 

[FNG]

Hey, thanks for the great reply!

I'll keep the BR9EYA plugs then but I'll have to gap them as the 2 sets in the boxes are gapped at 0.028, havn't checked the gap on the plugs in the motor. Tomorrow I'll be puling the carbs for a pre season cleaning and will be checking the needle and jetting. I did pull the RAVE valves today and piston tops are black all across the dome except for a little 1/2" semi circle around the intake and exhaust ports on the MAG side, the PTO side is uniformly black all the way across, but not charred looking. I also pulled the Y pipe and the PTO wasn't tight enough and there was obviously a tiney bit of exhaust leak out of the lower 1/2 of the gasket so maybe this had something to do with slightly to rich (?) conditino of the PTO side (which is how I read the piston heads).

Any reason to not use Amsoil? and is that for the first 100 miles only?, or should I be changing to something else... to bad as I've got a gallon of Amsoil sittin out in the garage. If not AMsoil... what brand? and do a premix at 150:1 from now on? or no.

The sled does have an aftermarket pipe and can.

I'm good with all of that but just trying to figure out how best to take care of the new-to-me sled that came with (aparently) way to little informatinon from the previous owner.

Er, stupid question... should I be runnig 91 octain here? I'm gonna drain the tank anyway and start with fresh but just want to treat the new gal right.

Oh, I did stuff and inspection mirror inside the exhaust outlet and the inside of the domes looked compleatly clean on the carb side of the cylinder(s) and about 1/3 of the surface had some tannish deposits on the exhaust side, not bad but it was worse on the PTO cylinder btw.

Again, thanks

 

[High Voltage]

Don't use any synthetic oil for breakin on any motor. Break in engine with mineral based oil, because you want rings to wear and seat in. I don't like to baby it either, don't go nuts but work it. After that everybody seems to be spit on what oil is best. I use a semi synthetic, I guess its the best of both worlds.