RK Tek SKI-DOO 600 Products

Check out our CUSTOM 600HO/SDI/RS Dual Ring Piston . Details located  HERE



Ski- Doo Rotax Series III 738cc Big Bore Kit for the 600HO and 700 Twin {150+HP}


The Series III 700 Twin is BY FAR the most impressive 700 twin on the market!! However;as you read above (hopefully), it is plagued by poor heat conduction from the piston to the cylinder wall via the ring. RK Tek tried various combinations, including cryo-genics and other treatments.. but was unsuccessful in solving the problems associated with the OEM pistons and rings.

This forced us to come up with another solution to the problem and the solution is the 738cc Big Bore kit. This kit is nothing short of OUTSTANDING!! Throughout the 2003 season.. we logged over 4000 TROUBLE-FREE miles on this kit!! This set-up is absolutely bullet-proof!! Besides being bullet-proof.. this kit produces some serious POWER! It is no contest against another 700 or even an 800 twin!! GONE!! are those inconsistent running DOO 700's!!

This kit is nothing but SOLID!!

The 738 is rated at 155HP on pump gas and has an EXTREMELY wide power-band. This engine's torque curve is so broad it is truly amazing!!

NOTE: The 600 HO cylinders can also be made into the 738cc KILLER!!

This kit uses your stock cylinders! It is a total SLEEPER!!

We strip and bore your stock cylinders to an 80.25mm bore. Your cylinders are then fitted with our custom sleeve.

The 600HO to 738cc is a Custom Sleeve vs a Re-Plate. The 600HO can be made into a 766cc engine because of this sleeve.

This kit is based around a cast piston made by ART ( The largest piston maker in the world) [All Honda, Yamaha, Kawasaki, and Suzuki engines run ART Pistons]

Here is the breakdown for this awesome kit!

Strip/Bore/Re-Plate your OEM Cylinders:             $525.00/pair
Custom Pistons including wrist-pins and rings:      $325.00/pair
Custom RK Tek Billet Head:                          $400.00/complete
Custom Cylinder Base Gasket:                        $25.00
RAVE Valve modification:                            $80.00/pair
Special Wrist Pin Bearings                          $32/set
                 TOTAL:   $1382.00

Porting Option.. Great performance addition but not required.

(NOTE: Porting IS Required on the 600HO to 738 Conversion The 600HO conversion is $200.00 extra due to the extra cost of the sleeve and sleeve installation)

The engine's port timing is drastically altered due to the piston's unique geometry. So, even is you choose the non-ported 700-738 kit, the porting is drastically altered.

RK Tek FULL Cylinder Port:                         $600/pair

RK Tek has developed an Over-Bore kit for the TNT/500SS/600 Series III Engine.


This over-bore turns your 600cc engine into a 662cc engine. We use the same piston in this kit that is used in out 738cc over-bore (600HO and 700 Series III Engine). Besides the awesome power increase, the benefit of not having the power-fade associated with the single ring piston (OEM) is what you will really notice when running this kit.

This kit consists of the following:

Bore cylinders to 80mm:                                   $175.00
Port cylinders to RKT Specs:                              $600.00/pair
Custom RKT Billet head:                                   $400.00
Custom base gasket and spacer:                            $50.00
RAVE valve modification:                                  $60.00/pair
Custom machined 80mm CAST pistons:                        $320.00/pair
Wrist pin bearings:                                       $32/pair
                                                  Total:  $1637.00

RK Tek SKI-DOO 800R to 860R Big Bore Conversion


RK Tek spent a better part of the 2007 Season developing a performance package for the new 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, CAST, dual ring, piston and a new billet head with a very efficient combustion chamber. RK Tek prefers to use “off the shelf” pistons whenever possible. This save the customer money and allows for the use of “proven” piston and ring combinations. RK Tek was very pleased to find a piston that would fit the bill and also allow for more strength than the stock piston. The OEM piston uses an odd 21mm wrist pin diameter. This new piston uses a 22mm wrist pin diameter.

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 8200 rpm vs. 8500 (stock 800R). 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)
  • 1 set of E-RAVE Valves
  • OEM Head (ONLY if you choose the “Cheater” Head option)

The cost of the kit is as follows:

Strip/Bore/Re-Plate stock cylinders:         $500.00 for Mono-Block
cylinder Porting:                            $600.00
Custom Machined CAST 85mm pistons  (2)      $150.00/each
Thrust washers	(4)                       $4.00/each
Caged wrist pin bearings  (2)                $16.00/ea
Wrist Pins - 22mm (2):                       $15.00/each
Base gasket (1):                             $24.00
Rave Guillotine Mod (2)                      $35.00/each
Billet Head (1)                              $400.00/each
                                 TOTAL:      $1972.00
827cc 172HP (PROVEN) Performance Kit

RK Tek Has developed an 827 (REALLY an 830cc) kit for the 800 Twin Engine. While we were not planning on big performance improvements in this little over-bore... we were soon proved WRONG! In side by side (stock 800 pipe) bench-mark testing against our RKT Mod 800 Engine Kit .. the 827 would pull 5 lengths on the hills and flats over our modified 800. This came as a HUGE surprise to us but the results do not lie. We were very pleased to say the least!!

This kit, on a 2001 MXZ 800 was dyno'd in 2005 at Dyno Tech Research in New York and showed 166.8HP with the STOCK Pipe and can. That is over a 40HP gain from the 2001 engine's power (124-130HP) For more on this kit and that dyno session please visit www. dynotechresearch.com and read a bit more HERE

NOTE: We can also make an 840cc kit ..BUT .. that requires the use of a Wiseco Piston vs. the Japanese Cast Piston . RKT MUCH prefers to stay with the cast piston for various reasons but if you (the customer) feels that the extra 10cc's is mandatory for your engine.. We DO have that option!

This 827 kit is unlike all other big-bore kits. It uses your stock cylinders and does not require sleeving the cylinders. When you sleeve the stock cylinders.. transfer tunnel area is GREATLY diminished. This is not a good thing! One of the short-comings of the Series III engines is the transfer tunnel area... IT IS NOT LARGE ENOUGH! Proper porting can partially resolve this short-coming BUT once you sleeve the cylinder.. the tunnel area is greatly diminished and can NOT be restored. Aftermarket cylinders can address this issue but are quite expensive!

Our 827cc kit does not effect the transfer tunnel area. The stock cylinder is stripped of the plating, bored out to 83.5mm and then re-plated. It is a TOTAL sleeper!! The piston used is a CAST ,Over the counter, Japanese Piston made by ART (The largest piston maker in the World).

For the 2007 season this Piston will be CUSTOM machined by RK Tek for improved reliabilty and Performance. It just keeps getting better!

This kit works extremely well with the OEM stock pipe but REALLY comes to life with the Decker Twin pipes.

The cost of the kit is as follows:

Strip/Bore/Re-Plate stock cylinders (2):     $525.00/pair
83.5mm pistons with wrist pins and rings     $335.00/pair
Custom RK Tek Billet Head:                   $400.00 complete
Custom Base gasket:                          $25.00
Modification of RAVE valves                  $85.00/pair
                                 TOTAL:      $1372.00

Options-- Great addition but NOT required!

Full cylinder port: (CNC PORTED(clicky) )    $600/pair
Caged wrist pin bearings                     $32/set
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