RK Tek SKI-DOO 800R to 860R Big Bore Conversion
WE ALSO have
this fantastic kit ready to go for the 800R ETEC!. Best Part: NO FUEL CONTROLLER
REQUIRED. This kit is LESS expensive
860R really benefitted from our custom Y Pipe. We will be able to offer this Y Pipe for all 860
customers. We will have a VERY limited supply on hand but should be able to get
them made throughout the season.
If you are interested in
this custom Y Pipe, please contact us.
was the FIRST to develop this 860cc big bore. It was developed in December of
2006 (remember the 800R was introduced in the 2007 Summit model only). Since its
introduction, MANY other shops have also developed an 860 for this power-plant.
While there, now, exists many 860cc Big Bore kits not all are created equal.
Think about Pizza, You can get a Ham and Sausage Pizza from 1000's of Pizza
Parlors and on the outside they will all look very similar.. BUT...once you bite
into them, they will, most certainly, not taste the same.
Same with the
different engine kits, while they might look the same and have similar
components (pistons etc.), once you crack the throttle, they will not
necessarily perform the same.
So, in short,
not ALL 860's are created equal. We, at RK Tek, take pride in our engine kit
developments. We are the originators!!
We are ,usually,
ALWAYS the first to
develop the over-bores for all Ski Doo Engines and couple this with our patented
head chamber design, you have a winning engine package.
More info on
the Ski Doo Big Bores:
added 600cc DOES add some power but it is NOT the main reason for the higher
several "players" in why the 860 kit surpasses the 180HP mark. This power is
reached through EXTENSIVE porting, a VERY unique piston design, and a patented
head design. These 3 coupled with the larger piston are what allows this engine
produce this great power.
Adding more cc's will simply not increase the output by anything measurable, in
fact, it MAY even lose power due to increased heat in the scavenged charge. In
any case, like mentioned above, the REAL reason the 860 kit makes the power is
the COMBINATION of the Porting (extensive porting is performed), Patented
Combustion Chamber Design, and Piston Design.
rights to this piston design it can not be used by ANY other shop without our
permission. It IS a KEY
component in this kit.
RK TEK 860R (and ETEC) CUSTOM
DUAL RING PISTON= 522 Grams
OUR BIG-BORE Piston is LIGHTER
than the OEM STOCK Piston!!
This allows the engine to run
much better and extends the crank-shaft life!
OEM 2016 ETEC PISTON =
A little history on the kit......
RK Tek spent a better part of the 2007-2012 Seasons
DEVELOPING and PERFECTING a performance package for the Rotax 800R Engine.
The new engine was torn completely down and inspected
for deficiencies. It was not much of a surprise to find that Ski Doo
had not addressed many of the problem areas that also plagued the
previous Series III power-plants. Of course we are talking about the
VERY inefficient combustion chamber (head) design and the “prone to heat
soaking and ring failure” piston and ring combination.
While Ski Doo did address the lack of
engine/cylinder/crank-case (not head) cooling with their new engine… the
“CORE” of ANY engine is the piston, rings, and head design and these
components remained virtually unchanged.
Since RK Tek is known for their unique and effective
methods for “fixing” Rotax engine issues, this new engine was surely
going to get the “full treatment” and get a “makeover”. This “makeover”
came in the form of a new, dual ring, piston and a new billet head
with a very efficient combustion chamber.
Speaking of diameter…did we mention that the new
piston is 85mm vs. 82mm? This turns the 800cc engine into an 860cc
engine. While 60cc is not a HUGE over-bore in itself… that fact that the
piston and ring design of this new piston is so much better than the
OEM piston gives the 60cc increase much more merit.
So, now, we have an engine with a MUCH better piston
and ring design boasting an extra 60cc. Couple that with a custom
combustion chamber designed specifically for this engine and you have
yourself a recipe for a very SOLID and POWERFUL power-plant that will
NOT power-fade (heat soak) on a long pull. This kit is also MORE
reliable than stock. In other words… It will perform better and last
longer than your stock engine set-up!!!
The new 860R from RK Tek is rated at 180HP on 91
octane fuel with the stock exhaust system. Peak power is accomplished at
8300 rpm. The torque curve is extremely broad and linear which allows
for VERY easy clutch tuning. Fuel economy is INCREASED over the stock
800R due to the more efficient engine.
The 860R is the “REAL DEAL” and will surely surprise and upset quite a few larger bore engines on the snow!
OK, What is required and what are the costs for this awesome kit?
RK Tek will need the following from the original engine:
Mono-Block Cylinder (stripped of reeds and all o-rings and coolant set-screws)
1 set of E-RAVE Valves
(main exhaust valves only)
Removal of 2 coolant drain set screws (located near each RAVE
Valve on the cylinder)
OEM Head (ONLY if you choose the “Cheater” Head option)
The cost of the 860R PTEK kit is as follows:
Strip/Bore/Re-Plate stock cylinders
$525.00 for Mono-Block
Custom 85mm pistons (2)
Wrist Pins (2):
Base gasket (1):
CNC Machined Rave Guillotine Mod (2)
Torqueline CUSTOM Billet Head
with RK Tek Patented combustion chambers(1)
NOTE: The ETEC 860 kit requires your stock head to be
Modified. This LOWERS the cost of the kit
by over $200 vs. the PTEK Kit.
A little "TECH" info on Fueling of a Big Bore Engine
When you increase the
efficiency of an engine you make it "better" then, with carbs or
EFI, the fuel requirement changes because the efficiency is
So, with carbs... you have a
stronger "signal" at the carb (see Venturi Effect-->http://en.wikipedia..../Venturi_effect )
so you actually get MORE fuel passing thru the jet even if the jet
is SMALLER..or the same size..
IF you need a bigger jet in
an engine, then you have NOT increased the efficiency of the
engine..,you can still be producing more power but the efficiency
has not been increased (probably reduced
The EFI operates on supplied
"inputs" that TELL the ECM that it needs more or less of "this" and
"that"... where, again, the carb system is purely mechanical.
So, with the advanced nature
of the ETEC, it KNOWS if it needs more or less, and, in turn,
supplies it.. BUT, there are limits to what it can do before running
out of "smarts"
This is exactly what we
focused on with the 860 ETEC.. we made the engine more efficient so
it would be able to remain "happy" in its given parameters!
Optional: RKT Custom PTEK ECM Re-program (PTEK ONLY) $160.00
THIS is an RK Tek EXCLUSIVE and is PROPRIETARY to RK TEK!!
We feel this mod is MANDATORY to having the PERFECT running Series IV PTEK Engine
PLEASE check out our YOUTUBE page for Videos of ALL of our Big Bore Engines