SKI - DOO 600HO/700 and 500SS Big Bore Kits


Ski- Doo Rotax Series III 734cc 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 734cc 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 734 is rated at 150HP (with full porting)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 734cc KILLER!!

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

We strip and bore your stock cylinders to an 80.00mm bore. Your cylinders are then fitted with our custom sleeve.

The 600HO to 734cc 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:      $370.00/pair
Custom RK Tek Billet Head:                          $465.00/complete
Custom Cylinder Base Gasket:                        $25.00
RAVE Valve modification:                            $80.00/pair
Special Wrist Pin Bearings                          $40/set
                 TOTAL:   $1505.00

Porting Option.. Great performance addition but not required.

(NOTE: Porting IS Required on the 600HO to 734 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 700-734 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 734cc 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:                                   $195.00
Port cylinders to RKT Specs:                              $600.00/pair
Custom RKT Billet head:                                   $465.00
Custom base gasket and spacer:                            $50.00
RAVE valve modification:                                  $60.00/pair
Custom machined 80mm CAST pistons:                        $350.00/pair
Wrist pin bearings:                                       $40/pair
                                                  Total:  $1760.00

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 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 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 85mm pistons  (2) 		      $175/each
Base gasket (1):                             $25.00
Rave Guillotine Mod (2)                      $35.00/each
Billet Head (1)                              $465.00/each
                                 TOTAL:      $2050.00
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