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You asked, Cat tech-sperts talk

AmSnow Web cruisers dish up questions on '06s and more!
How, why, where and what's the deal with that? Sound like you in your garage? Well, at AmSnow we want snowmobile consumers like you to get a chance to directly ask questions of the big brains at the Big Four.

Like we've done in years past, we gave our readers the opportunity to post questions on our online forums at

AmSnow then took your questions to the engineers at Arctic Cat, Polaris, Ski-Doo and Yamaha so they could be answered by the guys who actually design the machines.

Arctic Cat was the first to respond to your questions on the '05 and '06 sleds.
We'll focus on one manufacturer in each of the upcoming issues, so keep watching for your preferred brand. For now, let's see what Arctic Cat had to say!
THE T660
The T-660 is a fantastic all-around sled. I have put 4,000 miles on two of them, and my only real complaint is the "clunk" when the clutch engages. Is there a cure for this, and am I going to have to pay for it? member Clarky

AC engineer's answer:
The "clunk" you hear is the driven clutch engaging. The ACT driven clutch has a compression spring instead of a torsion spring seen on older driven clutches.
When you hit the brake, the driven opens slightly and when you re-engage you hear a slight clunk. Development is working on this but there's nothing new available at this time.
I've been very curious about the reed intake area on the lay-down engines. Are the lay-down engines more capable (efficient) of pumping air/fuel than the vertical engine design? member Cat-Racer

AC engineer's answer:
Yes, our lay-down engines are more efficient in this regard when compared to a vertical or upright engine. This was a key design priority in the initial development of our lay-down engines.

While the theoretical pumping is, roughly speaking, a function of bore and stroke, the efficiency of that pumping was optimized on our lay-down engines by testing many intake area placements and angles on the crankcase.

The incoming intake charge will inherently want to follow the same plane or line as the piston when it's moving in the upward or compression stroke.

We angled and positioned our intake to take advantage of this as much as possible. So, by laying our engines down, we had the ability to place the intake close to the cylinders for good response, but also keep the incoming fuel/air charge angle similar to that of the piston's motion.

It would be difficult to repeat this intake/piston travel angle in a vertical engine design, as in most cases the intake needs to be somewhat perpendicular to the piston motion for chassis fit and so on.

What changes have been made to the DD (Diamond Drive) to prevent water from entering the gear-case? member Krom

AC engineer's answer:
There are two lower seals in the ACT drive case. The outer seal has been reoriented to keep water from entering the case.

Has anything been done for the 2006 sleds to improve that troublesome sheave adjuster (0648-440) that keeps backing off? member Sportrac54

AC engineer's answer: All 2006 sleds have been changed to left-hand thread sheave adjusters. This eliminates any backing off of the adjuster that you may have experienced.
There also will be a new design replacement of the right-hand thread sheave adjusters on '04 and '05 models that are equipped with ACT driven clutch.
How much cleaner (EPA) will the 2006 700 motor (carb and EFI models) be compared to the 2005 models? Are there any horsepower gains for the 2006 700's? member Sandbagger

AC engineer's answer:
The 2006 700 EFI and carb engines have the same engine and exhaust dimension as the previous years 700 lay-down engines so there are no horsepower gains for 2006.

The fuel calibrations of both engines have been refined for cleaner low- and mid-range driving, along with a new three-dimensional cold drive away program (EFI model only) that provides cleaner cold to warm engine driveability.

These changes are the result of continued development on the 700 and were not necessarily driven by emission requirements.
What is the top speed of the new Crossfire 700? member Zipclean

AC engineer's answer:
The Crossfire is designed for the "Hybrid/Crossover" type rider. It has a 15- x 136- x 1.25-inch lug track, thus the top speed will not be as high as an F7 with the 13.5- x 128- x 1-inch lug. Depending on the conditions, you may see 100+ mph.

Does the Crossfire have a slightly stiffer rear suspension set-up? Will there be suspension options, possibly like the Sno Pro? member Bay City Bullet

AC engineer's answer:
The 2006 Crossfire will come with 120-lb. straight-rate ski springs. The models built this past February had 60 - 120 dual-rate springs that are excellent on groomed trails, but a bit soft in 2- to 3-foot bumps.

The new 120 straight-rate springs will carry the front end better and help in bottoming-out conditions. There also are two premium shock package options: an Ohlin's shock kit or a Fox Float shock kit. See page 104 in the 2006 accessory catalog.
What is the recommended sag on the rear suspension of an M7 LE? How much slack should the rear track have?

I believe the factory spec is 3 inches of slack with 10 or 20 lbs. of weight but that doesn't seem to be enough. With that amount of sag, it seems that the rear suspension can only move about 3-4 inches out of the travel. After that, the 162-inch track binds up and will not compress further. As it compresses, the rails take up all of the 3 inches slack and the suspension/track binds.

Many riders, myself included, see this as the source of the poor ride on the trail. That said, how much rear suspension sag can you safely run? If you run about 4-5 inches of sag with no weight on the track, it doesn't bind, but is this much slack safe? member MinnBobber

AC engineer's answer:
The recommended track sag on a M7 EFI 162-inch is 2.5 inches and 2 inches on 153-inch machines, free hanging under the rear bottom out bumper measured between the bottom of the wear-strips and the inside of the track wear surface. These are the dimensions that we recommend, and it's not to say that you cannot run it looser because that's possible with the involute/exvolute system.

Depending upon the condition of the track, it will tend to "expand" or "contract" due to temperature and conditions. The rubber in a track goes through many changes from when it is first produced until it has been "broken-in."

Tracks tend to shrink when they're first molded, and then tend to relax and stretch after their first few hundred miles.

Therefore, you need to check your track tension often after you start to run a new track. The M-Series suspension has been designed to have a track-tensioning feature to run our tracks as loose as possible until the suspension starts to travel through its motion.
The suspension does not "bind-up," but tends to slow down in travel toward the bottom of it's useful travel. This is because of the rate of tensioning we currently have.

In a sense, the track is acting like a big rubber band. It actually helps with the bottoming out in the deep "G" bumps, but isn't necessarily the way that we'd like it.

We have a little too much rate at this point to have the best ride that we could have, but the suspension really works in the deep snow and we're not willing to change it until we've proven the changes work in deep snow.

You can safely run sag in the track until it starts to slip or ratchet over the drive sprockets. There are some adverse effects that we've seen when the track is too loose, like a bad vibration coming from the track and rail interface. This can be remedied by tightening the track a little to alleviate the wave of the track coming off the drive sprockets.

Our focus for the M-Series is performance in the deep snow, and we firmly believe that we have the best snowmobile for it. This comes with some sacrifices in ride and handling, but we continuously work to improve our deficient areas and maintain our performance edge.

On the M7, there was speculation about the correct secondary spring tension and/or the spring rate. Some people opted to dramatically increase the secondary spring tension to give a better backshift in the powder or to put in a heavier rate secondary spring.
For '06, have the secondary spring tension spec and/or secondary spring rate been changed? If so, how does it compare to the '05 specs? member MinnBobber

AC engineer's answer:
There has been no issue with the secondary spring rate that we are aware of. One of the issues that we've had was the nylon spring adjusters. They came in on the small side and would allow the secondary spring to turn the adjuster and back off the preload.

This is easily fixed by adding a combination of aluminum shims (0.030 inches thick, product no. 0648-141, 0.060 inches thick no. 0648-142, and 0.100 inches thick no. 0648-143). The stock setting is 0.312 inches from the outside of the secondary cap into the white adjuster's top surface.

In 2006 we made a new adjuster (no. 0648-761) that has tabs on it so that the adjuster cannot move. They are interchangeable. As for a stiffer secondary spring, you can add one but then you'll need to add weight to the primary clutch to offset the stiffer springs effects. We've seen cases where the adjuster has backed off and the secondary had a poor backshift.

By preloading this back to the 0.300-inch area it will be greatly improved. We wouldn't recommend preloading the spring more than half an inch as the spring will coil bind and perhaps break the adjuster, or more
Are there plans to replace the plastic spring keepers and the plastic spring adjusters in the rear skid with aluminum ones? Over the last 10 years I have replaced dozens on my sleds. member Mainecat

AC engineer's answer:
2006 Firecats will have Fox shocks with steel spring retainers/adjusters. We offer aluminum machined rear arm spring keepers in our 2006 accessory catalog, available at dealers.
How about a bigger oil reservoir? I can only go about 120 miles and my oil light starts to flicker. Has this been changed for '06? member F-350

AC engineer's answer:
The oil reservoir holds 3 quarts of oil. Your oil light flickers as an indication that oil should be added reasonably soon.

The '05 and '06 oil light sending units will use two quarts before the light comes on with one quart remaining in the tank.

The original '03 and '04 oil light sending units would begin to flicker the light after using only one quart of oil, with about two quarts remaining.

Owners of 2003 or '04 models should see their dealers to make sure they have the updated oil light sending unit as a warranty item.

This update will make it the same as the '05/'06 models. You should also have your dealer check for correct oil pump settings.

NOTE: Clarification from Arctic Cat on Oil Reservoir question

We got calls from Arctic Cat dealers saying the above answer wasn't entirely correct. We contacted Arctic Cat with their comments, and here's where there's a clarification.

Arctic Cat says its comments should then have been that the company sent updated oil light sending units to all registered owners of '03 and '04 models with instructions to install them themselves. Instead of saying this was a warranty item in the article, it should have stated that Cat owners should "please bring your updated oil light sending unit to your Arctic Cat dealer if you do not feel comfortable installing it with the instructions provided by Arctic Cat."

If the Cat-provided updated units are installed, the '03 and '04 models then should behave like the '05 and '06 models, the light not flickering until only 1 quart of oil remains.
Any possibility of an F-series fan? member Bay City Bullet

AC engineer's answer:
Fan-cooled engines in the F-chassis are very difficult due to space constraints for carbs, cooling ducts and overall design.
Will a coolant temperature gauge be added as standard issue in the future? member Snappydave

AC engineer's answer:
It probably will stay as a warning light. Temperature gauges confuse many people. Sometimes the temperature rises a few degrees but the temperature is still within the safe operating range and won't hurt the engine
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