Premix recommendations

[mecjr22]

I'm running my 95 750 slt for the first time this summer and I want to make sure it'n not running lean. I put some oil in the gas to help with the lubrication after it has been sitting awhile, but I'm not sure the amount that I'm supposed to put in. I was also wondering if there was a reliable way to test the high and low speed carb adjustments with some premix in the gas. I was thinking make sure it's a little rich and then it should be fine when I go back just gas, but I don't know. Any help would be appreciated.

[surveyguy]

Re: Premix recommendations

oil doesn't make your mixture rich, lack of air (or more gas) does.
the best bet as far as oil mixture, is to do what most of us have done by now. Our old polaris' oil pumps are known for breaking. When they do, you won't know it. No oil is a sure killer. Best bet is to go pre-mix, and pull the oil injector pump off, make sure you pull out the plunger, and block off the block with a plate (easily purchased at SBT).

Next frequent things with our 750's, is the fuel pump. the original pump is not strong enough to keep fuel at the front cylinder, that WILL create a lean condition, which will blow a hole right through your piston. Best bet to do the other thing most owners have done by now, upgrade your fuel pump system by either purchasing an add-on pump, also easily obtainable throught SBT, or removing your old pump and going to a better pump (I did the add-on, so can't tell you right off what others use for their 3-outlet or ??). Look at the FAQ's and the tech articles for this.

Good luck, otherwise set your lows at 1/2 turn out or maybe slightly more, like 5/8 turns out, and keep your highs at spec settings too (again, look through tech's posts/articles to find your settings). Do not use the Soloc manual for these settings, they're incorrect.

[mecjr22]

Re: Premix recommendations

I appreciate the recommendations surveryguy. I do have a different fuel pump on my 750 from the guy before me, so I don't think the fuel delivery is a problem. However, the pre-mix is a great recommendation. I think i will have to do that. I thought that adding oil to your gas would make the plugs read different since you were getting oil from the pump and from the gas. However, I'm new to this so I guess that was just a logical conculsion. I also have ocean pro flame arrestors on there from the other guy and I'm in the process of adjusting the carb for that. I just thought that having pre mix in their along with the oil pump would through off my visual readings of the plugs when looking at the low and high speed adjustments.

One more thing is I was a bit confused on your recommendation on going pre-mix. It sounds like I would have to pull the motor to put a block off plate on. Isn't the oil pumped into the bottom of the engine cylinders along with the carburetor. Also, the plunger, is that in the top of the oil tank. Sorry if I'm not understanding your recomendation. I'm new to this and have only mastered the few things that I have done so far. However I greatly appreciate your reply.

Best bet is to go pre-mix, and pull the oil injector pump off, make sure you pull out the plunger, and block off the block with a plate (easily purchased at SBT).

[surveyguy]

Re: Premix recommendations

no problem-o. Good thing the other guy upgraded the fuel pump.

Yeah, the extra oil could leave some black deposits on your plugs, making them hard to read. If you want to read your plugs after a slow and/or fast plug-chop, Yeah, I'd wait until you are running at just the recomended oil/gas ratio, just for ease in reading, however a little extra oil should just burn off fine. When I read mine, there is a slight tan color, no black.

The oil injector pump is on the enjine block near the botom of the engine. I did not have to remove my engine to take it off, but my fingers are pretty nimble. Worth the extra hastle not to have to unmount the engine from the hull!

After you pull the pump out, it's driven by a plunger from the crank, which pushes the pump to make it pump. You don't want to leave that plunger in there floating round in your crankcase! (I know, pretty obvious).

The crankcase is not lubed directly by the pump, the oil is pumped to the intake manifold, just below the carburators. The gas vapors and oil mix together and get sucked inside your crankcase (all but the newest DI 2-strokes do this, like your chainsaw, etc.) which lubricates things in there. Then the 'fumes' are sucked into the combustion chamber and burned, then forced out (exhaust).

[mecjr22]

Re: Premix recommendations

Thanks for the reply to my questions. I found the block of kit on sbt, but my only other question is what do you do to the oil line going to the intake manifold. Do you just pull it off and leave it or are you supposed to plug up the opening. Thanks again.

[Technical Support]

Re: Premix recommendations

The kit comes with caps to plug the fittings.