I recently bought a 97 touring sle 500 fan cooled and the owner was still running the oil injection system and mixing fuel at about 25:1 for precaution. I am debating whether or not to disconnect the oil injection and going to 50:1 premix. Any thoughts on the positives and negatives. I am currently running a 98 tundra R on premix. Thx

running the oil injection and premixing the fuel at 25to 1 that is a lot of oil . if you stop injecting oil the mix half as much it the gas something is going to happen . probley not good, like boom . that thing must smoke like crazy I would think. I would mark the oil tank and see if the oil pump is even working.

 

i premix all my sleds.I run 40 to 1 at the least especially in my fanners

 

Davis - it does smoke quite a bit. I was surprised the owner was doing this. It's usually one or the other. I think I will burn this tank the way it is and then disconnect the injection system and go to the premix.

 

it will give you a piece of mind premixing you can only blame yourself and not the pump

 

I agree Scooby. The sled is strong and with 7400km it would make sense to switch to premix

 

A 97 on premix? Sleds have come along way. If it's dropping in the tank, and the pump is adjusted properly just gas and go!!!!

 

..at least u know that u have oil with pre-mix

 

True bark that's correct but for some reason the previous owner was using both premix and the pump that would raise a red flag Northern Tundra you should try to find out why this was done

 

I lost a outboard motor and a jet ski motor to failed oil pumps. That oil pump is 17yrs old. If you even think it is suspect rip it out and premix.

 

Davis-the oil pump is working as I marked it when I went for a ride. Does anyone know how reliable these systems are?

 

They are very reliable untill either the platic shaft that drives the pump breaks or the pump quits. I premix all our fanners except the 550. I remember back in the day there was lots of failures with these. One time I rebuilt a Formula SL 500 for a kid, went about a week and the pump quit and roached the top end. Never again.

 

Going pre-mix is good cheap insurance on an older sled.

 

There is always that fear that when you change out the oil tank or a leaky grommet that there will be an air bubble or air in the injector line and starve the motor for oil despite you bleeding the line at the pump screw properly. I was running 40 to 1 pre-mix, like i do in all my sleds, with the pump connected for the first gallon or 2 in a Mach 1. I had a pencil line drawn at the oil level in the take. After my first ride, I had seen the oil level go down and then I knew the pump was working. Now straight gas at the pump and go. Despite the pre-mix at 40 to1 and the oil injected, surpringly it didn't smoke more than any other time but then it wasn't 25 to 1 like mentioned above.

 

I agree with premixing older sleds..... we have had the oil cable snap twice on the Citation.... after that.... premix all the way

 

premixing is a safe way to go for shore but don't forget it effects your jetting more oil in the gas the leaner the jetting is .I would doo a cold then hot commpresson test, if the two test are off by 5psi it needs rings 10 psi it needs pistons and rings you may find that is why he was running so much oil . to keep it from scuffing a piston.

 

Thx everyone for the insight. I am going to switch it over to premix for peace of mind. Davis- do you know what compression I should see with this sled in cold?

 

Also took it for a ride today and hitting around 65-70mph. Based on this do you believe it's a compression issue

 

what you have for compresson varrys do to many factors . gage ,head ,base gaskit ,port hight ,piston tipe , you get the idear . what is important is that the compresson is close to even in all clys and close to the same hot and cold.

 

Pre mix and running the pump. You have got to be kidding me. Don't all modern sleds pump oil on a variable rate? 120:1 at idle and at WOT up to 20:1 therefore making a moot point why to use the injection system. Kawasaki did in the 80's and I would be certain that was a concept that advances to all sleds when the patten ended.

Save oil, protect your motor at WOT. What a deal! Can a person see that if you mix fuel at 120:1 your sled will burn down. Mix the oil at 20:1 and your friends will abandon you because you smoke WAY to much metaphorically.

Lets move on to the next item of contention like jetting and how the oil ration affects if your sled is running lean or rich. Better too much oil than not enough mixing concept. Wrong. She sure was running good before she burned down. To much oil is like changing jets, all good old time racers that understand the principles of A/F ratio.

Mixed your fuel at the pump with temperatures outside at -12 but you wanted to go sledding bad. Burn down because the oil does not go into solution at those temperatures.

The list is endless. Run the pump, replace the cable, if something fails well, the world is not perfect but I take my chances. The system was set up with the pump, you could guess the carburetor (or FI) was set up with the pump also. Why would manufacturers build an injection pump system? Reliability? The reasonable solution to this question is to consult the manufacturers recommendations or a forum's voice.

Compression can very widely. Way widely. Within 10% balance with other cylinders is a good rule. When the sled is hard to start as a result of low compression and even low on HP... IF the causes are from compression. The number you get on your gauge is a number to reference to that motor. One of my compression gauges (CG) will register only 90lbs in my cylinder the other cylinder 92lbs. Sounds bad right? When some friend borrowed my gauge I had to buy another and this new gauge measured 135lbs and 137lbs. Understand compression as a relative guide. If your motor has 10,000 miles you probably need a bore, piston and rings.

 

Does the premix get in to the crank case though verse oil injected ? Don't mean to interfere In the gentemens tread just curious

 

The only Ski Doo models which I might consider ditching the oil injection system on are the single cylinder Citations and Tundras and that is because I've seen several of them come into my shop with the oil pumps hanging onto the recoil housing with only a few threads of one or two bolts. The vibration on the singles tends to shake the bolts loose. So if you have an oil injected single, take a peek at the pump mounting bolts now and then. And some blue Locktite is always a good idea on them.

 

What we really need is a steel replacement gear and shaft to replace the nylon parts that have left so many ski-doomed.

 

Just do the maintenance on your pump, hell for a few buck replace the plastic gear every couple of years. There's tonnes of sleds out there with lots of miles/kms that have been done with the pump in tact. But if your scared to death of the pump run premix but as stated above be prepared to change all the jetting specs to make it right. It'll run with the settings it has now but they won't be optimum, you can't replace fuel with oil. and expect the same results.

 

Just do the maintenance on your pump, hell for a few buck replace the plastic gear every couple of years. There's tonnes of sleds out there with lots of miles/kms that have been done with the pump in tact. But if your scared to death of the pump run premix but as stated above be prepared to change all the jetting specs to make it right. It'll run with the settings it has now but they won't be optimum, you can't replace fuel with oil. and expect the same results.

so i unhooked mine on my 82 9500. so now what w the jets? it is bored .040 over, but stock jet settings.

 

If you run a 50:1 ratio thats what, 2%? So if your main jet was a 300, then 2% x 300 = 306. Hardly much difference. Plus, the oil also burns so the stated 2% difference is even less. You'll experience more jetting differences just from temp or altitude in one day than premix vs. injection-