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860 (180HP) Big Bore Kit for Ski-Doo 800R Powertek Monoblock |
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RK Tek SKI-DOO 800R to 860R Big Bore ConversionRK 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:
The cost of the kit is as follows:
Strip/Bore/Re-Plate stock cylinders $525.00 for Mono-Block Cylinder Porting: $600.00 Custom Cast 85mm pistons (2) $160.00/each Thrust washers (4) $4.00/each Caged wrist pin bearings (2) $16.00/ea Wrist Pins (2): $15.00/each Base gasket (1): $24.00 Rave Guillotine Mod (2) $35.00/each Billet Head (1) $400.00/each ----------------------------------------------------------------- TOTAL: $2017.00 |
