Engine Package Owner's Manual

Looking for more power, less weight and more fun? Would you like to do all that without sacrificing the bottom end driveability of your machine? That’s the recipe for an Xtreme Mod Package. Click here to read more about how we test.

The Problem: Both the Polaris and the Rotax engines have a lot of aftermarket parts available for them, all claiming to make them run better. We’ve tested a pile of pipes, reeds, heads, and big bore kits. Most are simply not effective at altitude for all around riding. If they make big top end power, they kill the bottom end and are miserable to drive in the trees. Some don’t kill the bottom end, they just don’t run any better than stock. A lot of the aftermarket stuff doesn’t do anything at all, just wastes your time and money. The other problem with mod kits in general is that most modifications do not work well in varying altitudes.

The Solution: After all of our testing, we’ve put together packages in a building block approach that deliver great bottom end and still provide increased top end performance. Most importantly, they pass the seat of the pants test, and don’t leave you wondering if you’ve just parted with your hard earned cash for some vague feeling that the sled might be better. First, we start with an increase in compression that solidifies the bottom end running quality, allows for fuel efficient mid-range jetting, and adds 2-5hp. Second, we adjust the ignition to work with the increased compression. Third, we change the entire exhaust system to add more power. We are constantly testing new exhaust systems from the aftermarket and updating our specifications and recommendations about which one to use. Fourth, we port the cylinders, enhancing the flow through the cylinders by polishing the passageways and altering the engine's port timing. Currently, we have only found porting to be effective on the 800 RMK. On the 600 and 700 Polaris engines, we have never found any significant all around gains in the power band by porting the engine.

Available Kits:

Stage I (2000-05 800 RMK, 2008-09 800 RMK): Xtreme head modification, single pipe, ignition change, carburetion/fuel injection and clutching calibration updated.

Stage III (2000-05 800 RMK, 2008-2009 800 RMK): Xtreme head modification, twin pipes, ignition change, carburetion/fuel injection and clutching calibration updated.

Stage V (2000-05 800 RMK): Stage III plus Xtreme porting.

Stage I (2001 800 Summit): Xtreme head modification, single pipe, ignition change, carburetion and clutching calibration updated.

The Benefits:
• Awesome throttle response for tight, technical spots.
• Crisper running: Compression cures the carburetion and enables us to lean the mid-range.
• More power for top end speed and climbing ability.

Who is it for?
These kits are for aggressive riders looking for more performance but who are willing to watch fuel quality and monitor the tuning & performance of their machine more closely than with an RMX kit.

What are the drawbacks?
These kits were developed to be used above 8000 feet. If you plan on riding below that on a regular basis, we recommend billet heads that can have the domes easily changed for frequent altitude changes. Also, you’ll have to use premium 91 octane fuel for safety with the increased compression. Other than that, there are no trade-offs or drawbacks.