Question:

Has anyone found the remedy for the Fusion’s vibrations and short belt life?

Rob Althouse

Response:

The MY 05 Fusion 90 and Switchback 900 were both given extensive recalls which included different durometer engine mounts and a new compound and thickness drive belt.

If you have an 05 you should take your sled to a dealer and verify this work was done.

MY 06 Fusion 900,s 750’s and SB’s were dramatically more reliable with few if any belt problems, reduced vibes and generally good performance.

Hope this helps,

Mark “Motorhead” Lester

Question:

I have a ’95 Ski-Doo Summit 670…just bought it and previous owner said it ran good but the starter rewind was broken.

Becky

Response:

Of course without having it here makes it very difficult to analyse but here goes:

1st thing is that the 1995 Summitt WAS hard on rewind starters and its components. The problem was solved in 1996 when they went to a new rewind which was much bigger in diameter and therefore less stressed.

The thing that concerns me though is the backfiring….that is definitely not good and would be hard on the rewind.

The 95’s were straight carbs I believe (versus H.A.C.-High Altitude Compensation in 96) and they were shipped jetted for elevation. We had to re-calibrate them for flat land use and thats one thing I would be checking to make sure it was done right.

Has the engine ever been apart? One of the most common causes of backfiring is someone tearing it down and not getting the rotary valve back in the right place/timed properly and you end up with intake at the wrong time resulting in backfiring.

Could also be some internal problems like scuffed piston(s) OR we have a leak somewhere, possibly a crankshaft seal.

Anyway, even though the rewind wasn’t the greatest, you’re still busting too many parts.

I believe if you find the cause of the backfiring the rewind problems will be alleviated.

Hope this helps.

Paul Prentice
Prentice Powersports
PrenticePowersports.com

Question:

How do you transfer the weight to the track on an MX Z 1000?

Don

Response:

Weight transfer is achieved in a greater measure by a combination (or any one) of these items.

* Soften the rear torsion springs
* Increase the preload on the front arm coil-over spring
* Let out the front limiter strap
* and most importantly increase bite (add traction products to the track).

You can also increase weight transfer by simply moving your butt and feet back on the running boards and seat and pulling on the bars when you launch.

Mark “Motorhead” Lester

Question:

I have a 2006 800 H.O. Summit and I would like to squeeze some more horsepower out of my sled.

Troy

Response:

Thanks for your email!

Your question needs some qualification.

Sure, you can increase HP but how much $$ do you want to spend and how much of a compromise are you willing to make for torque and reliability?

More peak HP will decrease torque – torque is what makes you move in the mountains – HP is elusive and hard to capture (clutch) efficiently at altitude. The Series III 800 engine you have is not known for super long term crank durability when modified.

I would recommend only basic enhancements like V-Force reeds and possibly a torque single pipe. Again, it’s about $$.

Motorhead Mark

Question:

I own a ’99 Mach-Z and I’d like to know which gasket between 0.3, 0.4, 0.6 mm is better and also what is the compression and top rpm.

Erik

Response:

The highest compression ratio will be achieved with the .3mm base gasket. Premium fuel must be used at all times if you go this route. Otherwise use the one that was originally on the engine.

The cold cranking compression is approx 135-140 lbs. We don’t print this due to variations in gauges and conditions. It is just a basic indicator of a healthy engine.

Any good performance shop will CC the cylinder head and combustion chamber if performing modifications.

The RPM if stock pipes are used is approx 8100. Later models turned slightly higher RPM closer to 8200-8300.

Hope this helps.

Gordie Radtke
Ski-Doo

Question:

Hello,

John Janssen

Response:

John:

Polaris carbureted 600HO engines use both a throttle position sensor and a knock sensor. The TPS reports the rider’s demands on the engine and communicates with the knock or detonation sensor.

Knock sensors enable the engine to run much leaner with stock jetting (ie: the stock jetting is set much lower from the factory than with a non-knock sensor engine).

The knock sensor basically tells the engine’s control unit to either advance or retard the timing when the engine is too lean or too rich. (advance when rich, retard when lean).

A bog usually indicates a too-rich mixture (timing retarded) and this may be a timing setting Polaris has programmed-in when the engine is first started so you don’t cook a cold engine.

I know some owners have leaned out their mains a size or two (depending on elevation) on this sled with good results but the net gain may not be worth the risk depending on how you ride.

If you run big lakes at wide-open throttle you could be running too lean up top too long. If you’re trying to beat someone in a drag race, running short bursts at WOT, the leaner settings may work for you.

You may just want to try being more patient, letting the sled warm up completely and let the electronics do their thing.

Kent Lester