The Ski-Doo MXZ 670 HO was one of the most powerful twin-cylinder Ski-Doos ever built. It was powered by a 2-stroke, 699cc, Rotax 670 HO (High Output) engine that delivered 125-128hp on the dyno. It was more powerful but tended to be less reliable than the 1997-1998 MXZ 670.
If you want to find out more about this classic high-performance sled, this post is for you.
We at PowerSportsGuide have compiled all you need to know into this Ski-Doo MXZ 670 HO review!
Ski-Doo MXZ 670 HO Review
The Canadian Bombardier released the MXZ 670 HO as the most powerful twin Ski-Doo in 1999.
Its official model name was MX Z 670 HO, but it was often referred to as MXZ 670 HO. (Hence, we’ll use that name in this post.)
The predecessor of this sled was the MXZ 670, which debuted in ’96 as a limited edition model. It went into full production in 1997 and was carried over to 1998 without any significant changes.
In 1999, it was phased out by the MXZ 670 HO, which was upgraded with a more powerful “Rotax 670 HO” (High Output) engine. This power source was a liquid-cooled, 2-stroke, 669cc, rotary-valve, twin-cylinder power mill.
It was designed with a wide range of innovative technologies, including:
- Rotax Adjustable Variable Exhaust (RAVE) valves
- Liquid-cooling system
- Dual 43mm Mikuni caruretors
- NGK BR9ES spark plugs,
- Cushion drive T.R.A.C. clutch
- “Two-in-one” tuned exhaust pipe with spiral muffler
As the name suggests, the Rotax 670 HO (High Output) delivered outstanding performance.
According to contemporary performance bulletins, the engine in the MXZ 670 produced 125-128hp on the dyno! In contrast, the predecessor base 670 “only” put out 115-118hp in stock condition.
Are you wondering what made the Rotax 670 HO more special than the base 670?
- Redesigned flat top pistons and head (which ensured higher compression)
- Tunnel porting
- Revamped ignition
- Larger, 44mm Mikuni carbs (dual)
- Redesigned exhaust pipe and muffler
- Different engine mounts and a lower engine position
- Higher performance (125-128hp vs. 115-118hp)
Due to its higher compression, the HO engine ran on 91 octane while the base 670 was happy with 87.
The MXZ 670 HO borrowed its engine mounts from the MXZX 440 racing sled, which made the engine sit lower.
In terms of performance, the MXZ 670 HO was an extremely fast snowmobile, which could beat many of its 700 brothers. The top speed of this sled was an amazing 100-110 mph under ideal conditions.
It shared its S-2000 aluminum chassis (a.k.a. “S-Chassis”) with the rest of the MXZ line, featuring DSA front and SC-10 XC rear suspensions. The latter was wrapped with a short, 121x15x.878” track.
Regarding measurements, the machine was 107.3 inches long, 46.2 inches wide, 42.5 inches high, and its ski stance was 41 inches.
Interestingly, the dry weight of the sled remained 502 pounds, which was indentical to its predecessor.
Standard features of the MXZ 670 HO included:
- 95-oz. oil tank
- 10.6-gallon fuel tank
- Front shock absorber kit (HPG)
- Acceleration and Control Modulator (ACM)
- Straight handlebars
- Carbide runners
- Heated grips and throttle lever
- Well countered seat
- Side padding
- Rear storage
- Brembo disk brake
- Hi-beam indicator
- Injection oil level indicator
- Mechanical fuel gauge
Ski-Doo MXZ 670 HO Problems
Even though the MXZ 670 HO was an amazing sled, it had some common problems which we have to mention. Without the need for completeness, the biggest issues with this model were as follows:
- Engine issues: The downside of the amazing performance of the Rotax 670 HO engine was its lower reliability. While the base Rotax 670 was known as a bulletproof unit, its HO counterpart had significantly more problems.
- Awkward engine position: Since this sled used the engine mounts of the MXZX 440, its engine sat much deeper, which made it hard to repair or modify.
- Handling issues: The MXZ 670 HO had some handling issues, which could be reduced by installing a pair of precision aftermarket skis. Its SC-10 XC suspension also had some early design flaws since its rear arm was prone to “kicking back” under a light load. Bombardier fixed this issue in the SC-10 II suspension.
- Lack of an electric start and reverse: Unfortunately, the MXZ 670 HO came without an electric start and reverse system from the factory.
Ski-Doo MXZ 670 HO Specs Chart
For your convenience, we’ve listed the key specs of the 1999 Ski-Doo MXZ 670 HO in these charts.
Ski-Doo MXZ 670 HO Dimensions and Weight
| Dimensions | 1999 Ski-Doo MXZ 670 HO |
| Length | 107.3 in (272.5 cm) |
| Height | 42.5 in (108 cm) |
| Width | 46.2 in (117.4 cm) |
| Ski Stance | 41 in (104.1 cm) |
| Ground Contact Area | 1034 in2 (6671 cm2) |
| Dry Weight | 502 lb (228 kg) |
Ski-Doo MXZ 670 HO Chassis and Suspensions
| Chassis and Suspensions | 1999 Ski-Doo MXZ 670 HO |
| Chassis | S-2000 |
| Frame material | Aluminum |
| Bottom Pan Material | Impact Copolymer |
| Hood Material | RRIM Polyurethane |
| Front Suspension | DSA |
| Rear Suspension | SC-10 XC |
Ski-Doo MXZ 670 HO Engine Specs
| Engine Specs | 1999 Ski-Doo MXZ 670 HO |
| Engine type | Liquid-cooled, 2-stroke |
| Cylinder Arrangement | 2-cylinder |
| Engine stroke | 2 |
| Cooling system | Liquid-cooled |
| Bore | 3.071 in(78 mm) |
| Stroke | 2.760 in (70.0. mm) |
| Compression ratio (corrected) | 6.2 |
| Maximum power engine speed | 8000 +/- 100 RPM |
| Idle speed | 1700 +/- 200 RPM |
| Displacement | 669cc |
| Carburetor Type | VM 44 36/37 |
| Turbocharged | No |
| Throttle Operation | Handle lever, right-hand operated |
Ski-Doo MXZ 670 HO Liquids
| Liquids | 1999 Ski-Doo MXZ 670 HO |
| Fuel Tank Capacity | 10.6 US gal (40 L) |
| Gas Type | Super Unleaded / 91 |
| Oil Tank Capacity | 95 US oz (2.8 L) |
| Recommended Oil | Bombardier Snowmobile Injection Oil |
| Chaincase Oil Capacity | 8.5 US oz (250 mL) |
| Chaincase Oil Type | Bombardier Chaincase Oil |
| Cooling System Capacity | 159 US oz (4.7 L) |
| Coolant Type | Coolant mixture: 60% antifreeze / 40% water |
| Brake System Fluid | DOT 4 |
Ski-Doo MXZ 670 HO Track
| Track Features | 1999 Ski-Doo MXZ 670 HO |
| Length on ground | 121.0 in (307 cm) |
| Width | 15.0 in (38.1 cm) |
| Profile Height | .878 in (22.3 mm) |
| Track tension | 30-35mm (1-3/16 – 1-3/8 in) |
| Track Alignment | Equal distance between edges of track guides and slider shoes. |
*Measure gap between slider shoe and bottom inside of track when exerting a downward pull of 7.3 kg (16 lbf) to the track.
Ski-Doo MXZ 670 HO Transmission
| Transmission | 1999 Ski-Doo MXZ 670 HO |
| Primary reduction system | Belt |
| Belt Number | 417 300 067 |
| New belt width | 35 mm (1-3/8 in) |
| Wear limit width | 32 mm (1-1/4) |
| Type | Automatic centrifugal engagement, infinitely variable |
| Drive | Silen chain enclosed in oil bath |
| Chain Drive ratio | 25/43 |
Ski-Doo MXZ 670 HO Electric Features
| Electric Features | 1999 Ski-Doo MXZ 670 HO |
| Magneto Generator Output | 220 W |
| Ignition type | CDI |
| Spark Plug Type | NGK BR9ES |
| Spark Plug Gap | .018 in (0.45 mm) |
| Battery | N.A. |
| Headlight | H4 60/55 W |
| Taillight and Stoplight | 8/27 W |
| Tacho and Speedo Bulbs | 3 W |
These charts are for informational purposes only! For exact specifications, please refer to the factory manual.
Ski-Doo MXZ 670 HO For Sale
The legendary MXZ 670 HO is still one of the most wanted classic Ski-Doo snowmobiles and with good reason. This aged sled offers an amazing performance for a reasonable price.
If you are considering buying one, you may find a used Ski-Doo MXZ 670 HO for sale on Craigslist, eBay, or snowmobile ad sites.
It’s also recommended that you visit the largest Ski-Doo snowmobile forums and Facebook groups.
Takeaway – FAQs About the Ski-Doo MXZ 670 HO
What year did the Ski-Doo MXZ 670 HO come out?
Bombardier launched the Ski-Doo MXZ 670 HO for the 1999 model year.
What years was the Ski-Doo MXZ 670 HO made?
The Ski-Doo MXZ 670 HO was marketed only in the 1999 season.
What size was a Ski-Doo MXZ 670 HO?
The Ski-Doo MXZ 670 HO measured 107.3 inches in length, 46.2 inches in width, and 42.5 inches in height.
What was the track size of the Ski-Doo MXZ 670 HO?
The Ski-Doo MXZ 670 HO featured a 121x15x.878 track.
How much did a Ski-Doo MXZ 670 HO weigh?
The dry weight of the Ski-Doo MXZ 670 HO was 502 pounds.
What kind of engine was in a Ski-Doo MXZ 670 HO?
The power source of the MXZ 670 HO was a liquid-cooled, 2-stroke, 669cc, rotary valve Rotax twin engine.
How much horsepower did a Ski-Doo MXZ 670 HO have?
The Ski-Doo MXZ 670 HO produced 125-128 hp on the dyno.
How fast did a Ski-Doo MXZ 670 HO go?
The top speed of the Ski-Doo MXZ 670 HO was 100-110 mph under ideal conditions.
Was the Ski-Doo MXZ 670 HO a 2-stroke?
The Ski-Doo MXZ 670 HO was powered by a 2-stroke engine.
Did the Ski-Doo MXZ 670 HO Have a Reverse or Electric Start?
The MXZ 670 HO came without electric start and reverse systems.
How Much Oil Did a Ski-Doo MXZ 670 HO Hold?
The MXZ 670 HO enjoyed an oil injection system featuring a 95-oz oil reservoir.
How Much Fuel Did a Ski-Doo MXZ 670 HO Hold?
The fuel capacity of the MXZ 670 HO was 10.7 US gallons.
How Much Does a Ski-Doo MXZ 670 HO Cost?
The asking price of a used Ski-Doo MXZ 670 HO averages between $1,000 and $3,000 depending on the condition.
