Snowmobile engine question

[nutz4sand]

Originally Posted by minibajaman

I am going to stick with the current layout and see how it works. I am not as concerned about the pump failing as I was about how it would deal without being gravity fed. I have clear hose out of the oil tank so I can see if it is flowing oil or not.

Your call and your coin if a problem pops up. For the small weight the reservoir is and the cheap cost of the tube to connect it to the pump IF you needed to buy a longer piece I would put it above the pump. Piece of mind stuff for me.

You may have clear hose but on a longer ride a problem may not be evident till the motor locks up. I would do ANYTHING I could to favor the side of NOT doing this and if that meant a special bracket to hold that reservoir. It would be my choice. Your way may never have an issue. But favoring the way it was designed in this case seems prefferred. Good luck with it either way.

[K-fab]

If the tip of the cable that operates the lever arm on the oil pump is secured with a plastic keeper, instead of a brass keeper, GET RID OF THE OIL SYSTEM. The plastic keeper will be eaten by dust and dirt and about 20 miles from the end of your first Mexico desert race, the keeper will no longer hold the cable in place, the oil pump will drop back to zero, the engine will suffer major lack of oiling and it's a long hot walk from there.

Go premix.

[Stomper]

I don't understand why every one says go pre mix. I have a polaris snow machine which I drive the sh$t out of. It has over 7000 miles and never had a problem with it.Knock on wood!! There are thousands of sleds that run fine with the oil injection. Does running them in the summer or the sand have any thing to do with it? Or is it just a peice of mind thing. I do agree though that if you mix then you know its getting oil.

[nutz4sand]

Snow is cold and not really abrasive. So add a lot of heat and the grit of dirt offraoding that most sleds do not see and you open doors to possible issues.

Many two stroke ATV's are oil injected and these systems were built for it a bit more than your average sled system.

I do agree that a good injection system will go many miles.

Its this simple. If the oil injection fails. Motor dies. If your premixing it will be there as long as there is gas in the tank.

Premixing falls a little back to the KISS idea. Keep it simple silly (use your own last word there.) Fancey systems (oil injection) are hell when they are well. But if they get sick you pay. Its your risk to take. I aint gonna lie. I LIKE oil injection. I have never had one fail on me. But I know many who have. So I can take the minute it takes to pour in the oil and shake the can. As said above. YOU need to decide.

What would be my first thign to think about is to hit all the sled forums I could that dealt with the motor I was looking at. Search and ask about oil injector issues. If there are just a couple of failures the system is a good one. But I have read some sleds have horried failures of the system and they switch them to premix even in the sled. Do the homework on the motor you plan to mess with and make the call. If your injection system DOES fail after the rebuild you can make it a premix! : ]

[Akpilot]

My .02
I'm a fan of oil injection, it's convienient and it works great in ALMOST all situations IMO. I have talked to 5 or 6 different mechanics and one Ski-Doo warrenty rep and they, depending on the situation, often blame it on the oil injection for engine failures when in fact it is a assembly problem or other failure (misterious) Or one they want to remain misterious. Most oiling failures are from the supply lines not the oil pump itself, air in oil supply line, hole in lines from pipes ect, ect. A lot of sled heads that remove the oil lines, myself included on my mod sled years ago, do for performance reasons and use reliability as a rational. The race sleds are premix as the manufacturers for obvious reasons have the oil pump well in the safe zone. The oil system also adds weight, requires throttle pull and thus thumb fatigue, and robs HP, the latter is definately small, but sometimes we can get anal.

Oil pump workings:
There is a line on the oil pump arm and one on the pump housing, these should line up at idle. This all but shuts down the pump as the engine is not calling for oil. As the idle increases not only does the rpm of the pump increases but so does the volume as the arm is raised. On the pump it has a torsion spring, when the pump arm is down (usually in the idle position) it is basically off. The spring wants to return the arm to the top oppsite the full throttle position which opens the pump to full open. There is a casting on the pump housing that does not let the arm keep spinning around untill the spring is unwound. This is a safty mechanism that if for some reason the arm brakes, cable brakes ect. it will return to full on position to protect the motor. K-Fabs situation it did not return to this position for what ever reason and I'm not sure in long term use in dirt this might be a valid factor. I say this as to let others know of the safety factor in the systems as it does return to full open and not to 0.

Buggyfreak34, I think your refering to me when you stated talking to someone about oil injection. With Polaris engines, Liberty series not Fugi made, they put extra oil lines to the outter bearings. If your oil pump has 4 lines comming out of the pump and you wish to remove the oil injection you MUST take off the jugs and drill the weep holes in the top of the case or you'll starve the outer bearings. Buggyfreak I would increase the oil pump arm to half or full throttle, VERY little oil is actually comming from the oil pump at idle. Test by taking off the oil pump and spin it with a drill in reverse (this is how to prime the pump) and see. The bearing oil lines provide little oil to the overall mix even at full throttle. Think of it this way put the pump at full and reduce the premix slightly, over all same mix but safe for the bearings, expecially the PTO bearing. Last thing you want is to spin that bearing and take out the case.

If you want to keep the oil system for simplicity (the reason Yamaha desigined it in the first place for the old 2-smoke motorcycle I believe), and ease of borrowing/sharing gas in the out back ect. Then I feel the oil injection system is a safe system as it is used by all snowmobile manufacturers. The long term reliability in desert may or may not have been tested in dusty situations and this should be the only concern when deciding on scraping the system and not on reliability of the oil pump itself. Therefore when planing the system make sure oil pump is well protected (chalange with Polaris Liberty engines as it is on the pull cord housing) and the arm can go all the way around to the casting stop. I have the oil tank below the engine and have had no issues with my FL800, I also made all my oil lines with good hose barbs and good hose clamps and have all lines protected from heat and abraision with wire loomb for extra protection.
I should also state that on the Polaris Liberty engines the oil injection and water pump are ran off a small kevlar belt and that has caused more failures than the oil pump ever has, so there is some validation for that reason alone change to premix as you're more likely to catch a overheat problem compaired to a no warniing oiling problem.

Once again these are only my opionions and really should reflect all those reading this. j/k

Wayne

[Stomper]

great info guys. gives a person something to think about.