Oil injection system or premix on a 2 stroke?

[tenn_blue59]

If you have seen any of my other threads, I am nursing a 91 Utility cart back into service. I bought it non-running, but it is in pretty good shape so far, and I enjoy tinkering with it.

On to my question... This is a 2 stroke motor, and has an oil injection system on it. Are the injection systems on these pretty reliable? Part of me says to play it safe, and disable the injector and just run premix. (What ratio should I use?). I have boats, dirt bikes and other 2 strokes, so there is usually a can of premix around. Recommendations?

Is there an accepted way to test the injection system? Something more technical than pulling the injection hose out of the intake and spinning the engine to see if it spits oil?

If I use premix, should I remove the injector pump (how?), since it would be running "dry" with no oil in the tank. Are these pumps vacuum operated (like the fuel pump) or are they mechanically driven? Finally, if the pump is removed, do I have to block off/plug where the pump used to be - I know I would have to plug the intake manifold hole as well...

Thanks in advance for the help. This sight has been a wealth of info, especially since this is my first cart.

[Dave Box]

I had the same issues when I found an 86 in the woods and decided to rebuild it. I decided that I would rather trust to premix than hope that the oil pump would not fail. I was motivated by the thought that the first warning of an impending oil pump failure would probably be a seized up engine. As I recall the oil pump is held onto the fan cover by two screws and it just slides off the end of the crankshaft. You will need to block off the oil line to the elbow behind the carburetter or the engine will suck air and run an extremely weak mixture. I did this simply by cutting the oil line short and driving a tight fitting screw into the pipe sealing it with some mastic and the little pipe clamp. There is no need to block off anything were the pump was.

The correct ratio for the PG2 engine is 128:1 unless you are breaking in a new engine when EZGO call for the first tank to be 40:1. (128:1 equals 1 ounce of oil to 1 gallon gas)

As I am sure you are aware it is not acceptable to fill your tank with gas and then add oil you should always fill a container and shake vigorously.

Anyway the choice of oil pump or premix is entirely yours

Dave Box

[EZ RIDER]

Go with premix, that way you know for sure that it is getting oil. I mix mine 1.5 oz per gallon, which is 85 to 1 ratio. Runs good with very little smoke.

[Pocono Country Boy]

Originally Posted by Dave Box

There is no need to block off anything were the pump was.


Dave Box

So on a PG-2 (early 89) there's no need to block off anything at the crank when doing this?

TIA for the info!

[Dave Box]

That is correct. If you look at the construction, the crankshaft goes through the crankcase and is sealed by the crankcase seal. Then the flywheel is bolted on and the fan is bolted to the flywheel. Then the fan cover is bolted on and finally the oil pump is screwed onto the outside of the air cover. At the end of the crankshaft is a slot and this drives the oil pump. As the fan cover is full of ducts to allow air flow across the engine there really is nothing to seal up. I removed my oil pump and just to tidy things up I also removed the oil tank as well. At 128:1 premix everything is running beautifully and I GPSed it at 17mph on the flat which isn't too shabby for a bog standard 2 stroke Robin engine.

Dave Box

[tguellich]

I switched to premix. The biggest change for me was that I realized my pump was pushing way too much oil into the mix under a load. Once I started premix, the thing runs like a champ, almost no smoke, and the plug looks perfect. I have been using a new oil called Rejuvenate, by Mercury and it seems to run better in my boat and the cart. The boat used to have some wicked idle shake but the new oil has eliminated it completely. Check the health of your muffler too, you may need a new muffler or to BBQ your old one.

[Pocono Country Boy]

Originally Posted by Dave Box

That is correct. If you look at the construction, the crankshaft goes through the crankcase and is sealed by the crankcase seal. Then the flywheel is bolted on and the fan is bolted to the flywheel. Then the fan cover is bolted on and finally the oil pump is screwed onto the outside of the air cover. At the end of the crankshaft is a slot and this drives the oil pump. As the fan cover is full of ducts to allow air flow across the engine there really is nothing to seal up. I removed my oil pump and just to tidy things up I also removed the oil tank as well. At 128:1 premix everything is running beautifully and I GPSed it at 17mph on the flat which isn't too shabby for a bog standard 2 stroke Robin engine.

Dave Box

Thanks Dave Box,

I have only had the cart about two weeks. It didn't run when I got it...replacing the fuel lines and filter, cleaning the carb and bypassing the pedal activated microswitch got 'er up and running and next I want to swap over to premix. I haven't had my head that far down inside the engine compartment to see how that's all bolted together so I definitely appreciate the info!

A couple cans of engine cleaner/degreaser and then getting that oil pump, line and tank removed and maybe I can get a better look how things all fit together down on that side of the motor ;)

Appreciate it!