RKT pison/head kit - Performance and Heat Issues - 12' PRO 800 Switch

[jrk]

I recently installed the RKT piston/head kit in my 2012 PRO R switchback. I had high hopes and aspirations that the kit would improve durability and performance. I have approximately 700 miles on the kit and I do have some concerns.

The sled prior to the upgrade with the stock head/pistons, the sled used to operate in the 120-125* temperature range…..usually closer to the 120 mark. Since the upgrade the sled runs anywhere between 128-134*F. Never any less than 128*. This is roughly 10-15 degrees hotter than it normally ran before the install in the same outside temps and snow conditions. The PRO R switchback has substantially more cooling area than an RMK and these temps I recorded are not on packed trail……..these temps are taken driving across a smooth field with 6-8 inches of snow

I’ve also noticed that when the sled gets up to that operating temperature, the RPMs start dropping off like as if it is losing power or running rich. There is nothing ailing this sled mechanically and it has LOTS of compression and the VES are not plugged. Sled has 1700 miles.

Something just doesn’t seem right. Having a lot of trouble clutching the sled because of it. I’ve had to back off on some finish angle on the helix or decrease some primary weight to compensate.

I was under the impression that the piston/head kit was to gain an additional 10-15 HP over stock….if it was to gain 5-8 HP I would have been happy…..it was the durability I was after! One would think if that was the case, I should be adding weight and helix angle to the sled, not taking it out.
I would have also assumed that the head would be do a better job at cooling……not making things worse.

At this point, I’m not sure I have gained anything with this kit.
It seems a lot of guys were putting in a thermostat bypass kit to keep these engine cooler, but most of those were on an RMK because of their lack of coolers......perhaps the crappy factory thermostat is the limiting factor with the piston/head kit?
Perhaps it needs a thermostat bypass kit like the BRP retrofit or a terra alps thermo bypass kit to keep the temps in check??

Could it be the temperature is causing the sled to go into a “self-preservation” mode because it running too hot, therefore retarding timing and dumping fuel in?

Perhaps with the temps closer to the 115-120* degree mark will give my performance back?

I know there are a lot of guys out there using the kit, so there must be someone with similar issues?

 

[04proxr800]

What weights are you using? what part of the weight are you loading? what are you revving? You shouldn't need springs, helixes or anything, just more weight....

 

[jpokryfki]

I'm having similar problems with my drop in kit. It's the rev 2 kit. I have the rooster weighs loaded to max in the heal and the rest in the middle and nothing in the tip and only have it loaded to 70g. I'm pulling 8000 rpm with this set up. The sled also gets hot really fast on the trail.

 

[jrk]

I agree. Should just need more weight....but that is not that case. Sled is running TEAM green (140/330) with 10-66's. Hard time pulling 8100 RPM.

 

[Jkinzer]

Those temps are normal with all the polaris RKT products and nothing to be worried about. However there are A LOT of variables that are not explained in your post
Elevation?
track length?
rider weight with gear?
Current helix and secondary spring?
what domes are in your kit?

we install a ton of these kits and have nothing but great things to say about them. at 8100 rpm you are missing almost all of the seat of the pants feel of horsepower from this kit as you should be running 84-8500. with the above questions answered i can tell you what is working for us here,
our elevation is 4-8k
all of my kits are 13.5:1 compression or higher

 

[jrk]

Elevation - 1500-1800'
Rider weight: Around 250lbs
Track: 136 x 1.75"
Clutch: Tied Team 75-59 with 140/220. Tried numerous other secondary springs with little change.

Domes are 12.5:1

I realize we are going to have very different calibrations because of elevation and track length etc.

Point is, this isn't very aggressive clutching and I was targeting 8300-8400 RPM as per Kelsey. This sled should pull this clutching easily....even with the stock 1.64 gears. Any more gear in this sled without additional traction was a waste of time. Tried 1.74 and 1.70.....both ratios caused major trackspin.

A 59* finish is similar to a 40* in a tss04. Factory finish angle was a 42. Factory secondary spring was a 123/203, I'm using 140/220.

 

[Jkinzer]

we don't run the Tied clutches but by what your saying you should be close to what were running in the tss04
at are elevation
with 155's were pulling
140-335 primary spring
epi belly buster 64gram weights
62-42-40 helix with a
160-240 secondary spring
pulling 8350-8450
on the 163's we have dropped to 62 gram weights to accomplish the same peak rpm, wish i had more to help with than that but our riding terrain and styles are just too far different to compare apples to apples. we have used the rooster weights in our big bores with great success as well, loading the heels heavy belly a little and no weight in the tip...
are you running 91 pump fuel?

 

[jrk]

I run 91 octane the majority of the time.

 

[Jkinzer]

have you tired dropping weight to 64's or 66's to see if it pulls the 83-8400 at that point?

 

[rmscustom]

Is it lean? What does your wash and plugs look like? Thought I read somewhere about ecu being lean at low elevation and a fuel controller was a good idea even though Rkt says its not needed on the 11s and 12s.

I know my 13 with the DI kit needed a lot more fuel at high elevation than Rkt's starting #s and wouldn't pull the weights it should until I gave it more fuel. Ecu seems to lean way out at high elevation also.

 

[bryceraisanen]

My 11 rmk 800 standard ran 125-135 before kit install. After install, 115-120. Also it takes an extra 10 minutes to warm up

Sent from my SGH-M919 using Tapatalk

 

[jrk]

Sled is definately not lean....if anything a little on the rich side. As per Kelsey, no programmer needed on the 12's as they were rich enough. 13 and 14 needed a programmer to add fuel.

 

[fullboredragon]

With mine I ran the trs mod and when them temps dropped the power came back, I believe that the ecu pulls timing above 130f. Also if you are running a can try the stock silencer, I picked up a couple hundred rpm just losing the can.

I think the higher temp are because of sensor location and the fact the coolant is getting more heat out of the head. I was able to run 13:1 head on regular gas without issues on mine @ 1800' elavation

 

[ak]

Is your thermostat in the correct position? In line with the bolt holes. If not it will run hotter.

 

[polarisperformance]

Last year I was running a drop in kit in my sba 2011 and I also noticed higher engine temp with the kit ( 6-8 Celcius) ... very hard to clutch too ..... sometime it was very fast and pull 8500 on snap but on long WOT RPM was falling to 7900 - 8000. It was running on the rich side too .
I was running stock clutching

Finnaly seized the engine after 800km

 

[jrk]

Siezed the engine.....cripes I sure hope not!

Interesting comment on the stock can. I do run a Jaws can on it, but I ran one before the kit and had no issues. I spoke with Kelsey about this silencer and Jaws was one of the few manufacturers he actually endorsed. I had a sled shed can previously and he said to get rid of it.....was one of, if not the worse can he ever tested.

I have no problem going back to the stock can if it will help eliminate the silencer as a possible cause....

 

[snobyrd]

I recently installed the RKT piston/head kit in my 2012 PRO R switchback. I had high hopes and aspirations that the kit would improve durability and performance. I have approximately 700 miles on the kit and I do have some concerns.

The sled prior to the upgrade with the stock head/pistons, the sled used to operate in the 120-125* temperature range…..usually closer to the 120 mark. Since the upgrade the sled runs anywhere between 128-134*F. Never any less than 128*. This is roughly 10-15 degrees hotter than it normally ran before the install in the same outside temps and snow conditions. The PRO R switchback has substantially more cooling area than an RMK and these temps I recorded are not on packed trail……..these temps are taken driving across a smooth field with 6-8 inches of snow

I’ve also noticed that when the sled gets up to that operating temperature, the RPMs start dropping off like as if it is losing power or running rich. There is nothing ailing this sled mechanically and it has LOTS of compression and the VES are not plugged. Sled has 1700 miles.

Something just doesn’t seem right. Having a lot of trouble clutching the sled because of it. I’ve had to back off on some finish angle on the helix or decrease some primary weight to compensate.

I was under the impression that the piston/head kit was to gain an additional 10-15 HP over stock….if it was to gain 5-8 HP I would have been happy…..it was the durability I was after! One would think if that was the case, I should be adding weight and helix angle to the sled, not taking it out.
I would have also assumed that the head would be do a better job at cooling……not making things worse.

At this point, I’m not sure I have gained anything with this kit.
It seems a lot of guys were putting in a thermostat bypass kit to keep these engine cooler, but most of those were on an RMK because of their lack of coolers......perhaps the crappy factory thermostat is the limiting factor with the piston/head kit?
Perhaps it needs a thermostat bypass kit like the BRP retrofit or a terra alps thermo bypass kit to keep the temps in check??

Could it be the temperature is causing the sled to go into a “self-preservation” mode because it running too hot, therefore retarding timing and dumping fuel in?

Perhaps with the temps closer to the 115-120* degree mark will give my performance back?

I know there are a lot of guys out there using the kit, so there must be someone with similar issues?

I've had same issues, I removed Kelsey head and piston kit last fall to replace it with bikeman fix kit and pipe and I'm still chasing the same issues as yourself.
My ele is 3000' I'm on a 13 155 pro, I weigh 160, I've tried 57,59 tied as well as carls helix in the tks, t stat bypass installed, SLP weights from 71 to 68 grms, 64 epi weights several sec springs, boondocker programmer with 4 to 5 % in mid and 8 to 9% up top, I've tried lots of fuel settings and get same or worse results.
wen i loaded the SLP to 71 it pulled hard on bottom end but would only rev 79 to 8000, I've lowered the the weights to 68 and still only see blips of 8300, so im stumped.
I rode a stock 14 yesterday with 64 grm and was hitting 8250.

 

[rmscustom]

I would say you guys are chasing problems that are not the kits fault.
Fuel filter?
TPS adjusted right?
Exh valves clean, bellows not ripped, the right gasket installed?
Exhaust donuts good?
Clutches clean, not binding, rollers, alignment, center to center and with good springs?
New belt, deflection set right?
Exhaust sensor good?

Snobyrd, how do you like your crow? Jk

 

[jrk]

I would say you guys are chasing problems that are not the kits fault.
Fuel filter?
TPS adjusted right?
Exh valves clean, bellows not ripped, the right gasket installed?
Exhaust donuts good?
Clutches clean, not binding, rollers, alignment, center to center and with good springs?
New belt, deflection set right?
Exhaust sensor good?

Those are all good things to consider........but nothing you mentioned above is an issue with my sled. The clutch springs, alignment, center to center, belt deflection and VES valve maintenance and function are some of the first things that have been checked/replaced to eliminate them as a possible cause.

TPS and fuel filter are not something I considered since the sled ran fine before the kit install...?

Why the sudden spike with operating temps? If this causes an issue with ECU to dump fuel and retard timing.....therefore hurting performance.......that makes sense to me.

That means a thermo bypass upgrade should correct things....or at the very least make them better?

Problem is I'll have to wait until next season to find out as our riding conditions are crap.....LOL

 

[rmscustom]

I see the same temps as you and feel some loss of power above 130 just nothing as drastic as the loss your seeing (comparing different model and year sleds though). Mine will have the bypass next year but like you its looking like I'm outa time for this year.

Just a thought. Could the higher coolant temps actually be from a more efficient head design that removes more heat resulting in higher coolant temps?