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Formula Mach 1 Ski Doo

I know this is car talk. But I know many of you guys, and girls, work on motorcycles and snowmobiles. For those of you who do, if you have a good idea let me know.

I have a Ski Doo Mach 1 early 90’s. Just got it this season. It starts ok. Runs great once started. After it warms up, perhaps 3 miles of running about 50 - 60 mph, it starts to lose much power. Almost makes you feel like it is going to die before you get back home. Actually the other day it did die after it was idling and it would not start until I let it sit for 5 minutes.

I am going to try putting new plugs in and getting a can of SeaFoam, half a can. I was told the clutch was changed very recently. I am not sure if clutches that are bad have troubles when warm and not when cold. And it does not feel like a clutch problem. And of course like I said, one time it died at a idle and did not want to start. This would have nothing to do with the clutch. Seems to be in the motor so I am thinking either electrical or fuel. It will just start to dog down and the sound is greatly changed. Sounds like a booooooo noise if that makes any sense. When it is going good it has a higher pitch when the problem starts it is a lower pitch. Anyone have a Ski Doo and have this same problem?

Does the gasoline you use contain ethanol?

If so, that could the problem.

In 1992, Minnesota was the first state that mandated that all gasoline sold in the state contain 10% ethanol. The problem was, nobody knew what the damaging effect the ethanol would have on older fuel systems.

Ethanol is very corrosive, absorbs moisture, and eats rubber components in older fuel systems.

That’s why the Minnesota Street Rod Association filed a class action law suit against the state of Minnesota, arguing that the state does not have the authority to force a private party to use a motor fuel that results in damage to that private parties personal property. And if that party must use the fuel mandated by the state, the state is responsible for the repair of said private property damage.

The MSRA won the case. And that’s why we have access to non-ethanol gas in Minnesota.

So, if you have a steel gas tank, original rubber fuel lines, and original carburetor, and running ethanol gas, that’s probably the problem.


Let us know what the old plugs look like and if the new ones help.

Its a two cycle engine, have you checked the oil injection system. This is something that two cycles do when they don’t get enough oil, and of course they wear out really quickly.

If all you can buy is gas with ethanol, buy the highest octane you can and treat it with marine fuel treatment and stabilizer. The oil injection systems on older motors can be suspect. I’d abandon the oil injection system and just put 2 stroke oil in the gas tank and get some advice online for the proper oil to fuel ratio.

Assuming this is a motor with carb’s they could be gunked up due to ethanol fuel. Also fuel lines can deteriorate internally and a hot bad fuel line could collapse and reduce fuel flow. You might be looking at replacing all the fuel lines, and rebuilding the carb’s to get it reliable. Early 90’s machines were not made to handle ethanol in the gas.

One thing not mentioned is Carb icing.

I believe most gas stations do have 10% ethanol. I did look up those that do not and did find some in my area. I will fill the tank up with this.

I will also fill up the two cycle oil reservoir, I did notice it was about half full.

How do I test the oil injection system? And is that something that gives problems when it is warmed up driven for a couple miles?

I do not know when the sled was driven last, but it does have 2014 stickers on it. So I assume it was driven a couple years ago. The guy did seem a little untrusting. The machine is in almost like new condition body wise.

There is likely a coarse screen filter on the fuel pickup in the tank that may be getting clogged with dirt and debris accumulated over the years. When the engine is off the trash will drop off and settle to the bottom but with the engine running, especially at high rpms, continious high vacuum can draw the trash up to restrict flow.

You also might want to pop open the gas filler cap when it gets sluggish to see if the power comes back. Just a quick way to check the gas tank vent.

OK Thanks to all you guys. I will try those ideas and let you know.

I don’t know of a test for the oil injection function, you’d have to have a service tech check it for you. I’d suggest putting some 2 stroke oil in the gas tank, and then watch the oil tank level as you use the sled. If the oil level drops then it is working, if not … A bit too much oil isn’t going to hurt the motor, it will just smoke a bit more at idle. Too little oil will cause damage. Until you are sure the oil injection is working, add some oil to the gas to be safe.

I just called a Ski Doo shop and they said their best guess was it has something to do with either the Stator or CDI box because it is a heat issue. Runs good when cool or semi cool, but once it gets hot, then it is having problems.

A bit too much oil isn't going to hurt the motor, it will just smoke a bit more at idle.

If you go this route be sure to carry extra spark plugs. Too much oil will foul them, and it will happen when you are absolutely as far from as you can get from you car, home, base of operations. Don’t ask how I know this, I just do. :blush:

I will go in circles and stay close to home then.

I talked to another expert service center, and he said it would not likely be electrical. He said that I should look at the belt adjustment, belt wear, 2nd clutch wearing out, and carbs.

I will be also do a compression test and test current spark plug spark when it gets warmed up.

Took compression text today. Left side was at 110 right side at 115. Did 3 test for each one, came up the same every time. Seems pretty good to me. It is a good work out pulling that thing over.

Would not start today however. Changed plugs and still would not start. Did fire and almost start a few times. The problem must be something with fuel since now being cold it is having problems starting. I would think anyways. Will try again another day when I have more time.

Finally got running yesterday. It would keep firing but not start. I got it to start by sticking something between the throttle handle while pulling over and she fired up on first pull.

I did put in new plugs. Added some oil to the gas. Did the loosen up gas cap while driving thing. Did nothing. I drove it for about 20 miles non stop. It started running sluggish after about a 1/8 mile. The fastest I could get it up to was about 50 mph. It should go over double that. The speed did not go any faster once the throttle is opened up half way. Or at least no more than a few mph. When driving it would seem to either miss or like the clutch was causing it to seem like a miss if that makes any sense. When I raised up the back end and let it rev up like that and let the track spin it had no missing whatsoever. Once it was running it ran perfect and could stop it and pull start it in 1 pull easy.

I was told it got a new clutch from the guy I got it from this year. One service place said it could be a problem with secondary clutch. We are having a snow storm soon. I think tomorrow if I take it down the road should give me a good indication if it is the clutch. When I used to drive my Kawasaki Invader I had a similar problem. It would run sluggish in snow but on the road would go about a 100 mph. I think if the Ski Doo runs at a 100 on the road that would tell me it is the clutch. Any one agree that is one way to test the clutch? Because it has less work to do going on the black top, easier for it, which it should perform better if that is the problem.

I did a compression test both sides were between 110 and 115.

Because it has less work to do going on the black top

Just a note of caution about running down the road with insufficient snow to cool the sliders and underside coolers- you could cause a lot of premature wear and possibly overheating, especially at those speeds…

Sounds like carb problems.

Just a suggestion and I haven’t read all the comments but if the shop suggested a spark problem, go buy a $10 spark tester so you can rule spark out when it doesn’t start. Then you know you have a fuel problem.

As an aside, last weekend driving cross country, a snow mobiler was riding the ditches. I was going 65-70 mph and barely keeping up with the guy. I don’t know but I think 70 mph on a snow mobile with no seat belts is a little too fast. We need young people around to keep paying for us old people.