keep seeing threads about pre mixing and i just wondered why.

 

pre mix is for people who have a broken or have removed their OMP (oil metering pump) which dribbles engine oil into the carb to lubricate the apex seals. Or its for people who are paranoid like i am. that and a proper smokeless ashless 2 stroke oil will keep your engine cleaner than having just motor oil pumped into the carb.

 

people also do t for turbo applications. keeps things safe and when running boost on a rotary. the pressure makes your OMP not flow enough oil in to your apex seals.

 

If you have not measured the flow coming out of the lines from your OMP you should be premixing. I wouldn't trust a 25+ year old pump and plastic lines to keep the seals lubed without testing it first.

 

how do you test it?

 

The FSM has a procedure. Basicly you unhook the lines and run the engine at a certain speed and measure the output.

My memory is vague but I think its approx. 6cc's @ 2000rpm. Not sure thats right check fsm.

And oh, you should premix during the duration of this test.

 

i just ordered the digital fsm off ebay, you guys think it will be in there or should i get the paperback? also what tool do you measure it with?

 

You can download the FSM free off the forum. Sgt. Fox has them on his website.

It is in all of them.

Anyway you can use little plastic mixing cups used for measuring and mixing epoxies and such. You can usually find them @ walmart or parts stores.

Be very careful with the plastic lines , they will be old and brittle, the little clips that secure them can be fussy.

 

there is no 82 FSM on there. am i good with the other ones?

 

considering the mechanical OMPs all produce the same volume, in this case i would say "good enuf".

as for premixing. yes it has other benefits and drawbacks, but there should have been some info in the other threads you saw that gave those pros and cons. this horse has been beaten to death, resurrected 50 times then beaten repeatedly again.

the OMP system works ok but adds to carbon buildup inside the engine and is rather minimal for the internal lubrication for abuse. premixing takes up the slack if you drive the car hard as you can increase the amount of lubrication inside the engine. next benefit is that 2 stroke oil actually helps to inhibit carbon buildup rather than promote it as the OMP system does. drawback being that you have to measure and add oil to the gas tank prior to filling up.

 

actually this isn't the case they vary with the year/model, the amount of oil goes down as the cars get newer, except for the turbos, those supply more oil.

although it IS really hard to measure 3.5cc's.... that's like 4 drops

 

Remember you can also convert the OMP to feed from an auxiliary tank, which you can keep filled with 2 stroke oil. IMO, it's the best of both worlds. Not having to bring a chemistry set with you to the gas station, and not having to worry about dirty engine oil in your combustion chamber.

http://jhbperformance.com/products.php#oil_system

http://www.rotaryaviation.com/oil_in...p_adaptors.htm

That is probably what I'm going to do when I finally rebuild my OMP

 

This is a good idea. I am going to look into this some more.
I always thought my OMP wasn't enough, so I always ran a little
Premix in as well. I hated doing that. This might be the better solution.

 

Turned out who ever did it didn't fill it enough.