The 2007 Polaris 600 HO IQ is a prime example of Polaris doing what they know best. This is aimed squarely at the heart...

The 2007 Polaris 600 HO IQ is a prime example of Polaris doing what they know best. This is aimed squarely at the heart of the market, the 120 HP trail sleds. The “new” IQ is the fresh streamlined look with the lighter yet potent small block 2-strokes. And now for 2007, the small blocks are fully-automatic with CleanFire Injection (CFI).
The carbed, 120 HP 600 H.O. is still offered, but the new CFI 600 H.O. gets a four-injector fuel delivery system, a new head and power output of 125 HP! From a 600!
Once you get past the lightweight excitement, reality sets in. This is an a-arm Polaris, so you know that means light steering effort and predictable handling. Only Polaris utilizes a variable caster front suspension, and the result is a more predictable response through the rough. The effective wheelbase is lengthened as the suspension compresses and the caster angle is relaxed, making for a machine that is forgiving and easier to hang on to when the terrain gets wicked.
Polaris riders who have been on a Switchback 600 or RMK 600 for the past year know how good these new little IQ brothers are going to be. The 600 2-stroke is a new motor (2006) and is very similar to the 600 small block of EDGE days, at least mechanically, and it works. Now for 2007, the EPA thing has been haunting Polaris for long enough as they have their CleanFire Injection on the 600, and the all-new 700 (Dragon).
This is a battery-less system, so there is a weight advantage. No choke, all automatic, even fuel quality. Air temp, water temp, throttle position, knock sensor, engine speed, and electronic power valves are all part of the formula. Each cylinder gets an injector in a transfer port and one firing up into the incoming airstream at the bottom of the reed cages in the crankcase.  Pull the rope, usually twice unless warm and the fuel rail is pressurized, and she goes. It revs quickly, up to around 8200 RPM, and 125 HP. Doesn’t matter if it is warm or cold, low or high, the engine will be fed the right amount of fuel. The CFI is 43% cleaner than the industry baseline, so they’re EPA-compliant all on their own.
It really is curious how well this “traditional” engine, exhaust up front and intake in the rear, fits and works in this IQ chassis that was originally designed more for the laydown big-block 755 and 900 engines. Does it really matter? Doesn’t seem to. In theory, the big blocks had the mass more centralized and lower, but they weighed more. Those who are very familiar with a 755 or 900 IQ and ride the small-block 600 or 700 will instantly recognize what a different response there is when you try to throw the sled around a corner or in most any maneuvering. You’d swear the sled looks and feels about 50 pounds lighter.
The 600 engines did get some tweaks for 2007, in addition to the CFI option. They all get new cylinder heads, for commonality (to be able to use one part on both engines). Being the fuel supply was going to have to be trimmed with the CFI, the cooling system got attention (less fuel means less cooling) with a redesigned water jacket for, you guessed it, improved cooling. No longer can extra fuel be thrown at an engine as coolant.
We’re also told there is a new airbox design which results is less vacuum, along with improved performance and serviceability. The fact a manufacturer is making mention of serviceability is a good sign, as so many of the new models place more emphasis on cosmetics than ease of maintenance.
Being a batteryless CFI, the electrical output of the engine had to be increased to supply the demand to do the number-crunching. Thus, the 600s get a larger flywheel and charging system, along with a larger PTO end (and new clutch taper).
Another big difference between these new small block engines and the ones they replace are the EC power valves, or VES. They’re electronically controlled, via solenoid, mechanically (pressure) activated for the best of both worlds. Making a 2-stroke EPA compliant comes down to a few basic requirements; electronic power valves, a knock sensor, good cooling system, smart fuel and ignition control, and accurately metered fuel delivery. And whether you give a hoot or not about the EPA, you will appreciate the improved fuel economy from the CFI – said to right on par with the Ski-Doo SDI (as it should be) which should mean 15-18 mpg (it all depends on the conditions). Combined with a larger (11.7 gallon) fuel tank, trail riders everywhere should relish the range compared to a big block.
Polaris has fitted the IQ 600s with the latest TEAM roller secondary, the LWT (lightweight) that should make a difference on top end.  And you’ll find the Rider Select is gone on these machines, in favor of a lighter fixed post that is in the right place for most everyone. The goofy radius of the Fusion handlebars is gone, as is the look, name, weight, and all of the baggage. These new handlebars are wider, with hooks, and are where they’re supposed to be. The chassis itself is five pounds lighter, not to mention the difference in small-block vs. large block. The IQ 600 HO has a weight spec of 475 pounds. Now we’re talking.
One issue from the 2006 IQs was steering effort, remedied by a tweak to the ski and spindle. The skis now sit slight forward on the spindles, resulting in reduced steering effort. Most noticeable is breaking the skis loose from a straight ahead condition.
Ryde FX high-pressure gas shocks are found on the A-arm IFS and in the center of the IQ rear suspension, with a Fox PS5 position sensitive rear track shock. Not as cush as the M-10, but excellent through the stutters and more capable in G-outs. Bottoming is rare, transfer is adjustable, skis stay flat, it’s durable and easy to service. This is more high performance trail than it is cross country, but very capable. The single most important calibration is proper preload and ride height for the rider weight (torsion springs). And if anything, the 1” Shockwave track is a bit lacking (value instead of all-out performance) compared to the likes of a Ripsaw or Hacksaw. It’s OK, but could be better.
It really is too bad Polaris didn’t have these sleds two years ago. They are tried and true Polaris, almost as dialed as an Indy 500. The character is intact of a strong motor with a linear powerband, smooth clutching that lets the 2-stroke sing, easy steering, and a rear suspension that doesn’t surprise you. Ever. Maybe the wind protection is somewhat lacking compared to an EDGE, but this is what we give up for the sleek lines and styling originally from the deep-snow RMKs. These should be the lightest sleds in the 120 HP class, should get as good of fuel economy as any, they should be good enough to get Polaris riders back on a Polaris. While not revolutionary, they are now back where they needed to be – at the heart of the market.
The 2007 Polaris 600 HO IQ ($7,999) and 600 HO IQ CleanFire ($8,599) both are offered in Indy Red and Black Metallic. The Cleanfire LX adds electric start (all have push-button electronic reverse) in Pearly White with an M-10 in the rear for ($8,799).

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