Question on rotor lubrication - no throttle input.

[Prof]

After watching a Top Gear rerun about SAAB\'s the other day, one of the older SAAB vehicles was a 2 stroke engined car.  One of the design flaws was that the engine received no lubrication when the car was going down hill or if the engine was allowed to coast.
 
This got me thinking - Mazda designed the OMP to deliver oil via the oil injectors - and that happens when the throttle is shut too.  But what happens with the guys running premix ?  Surely this problem could occur under the same \'lift-off\' throttle inputs, as the ECU will do full fuel cut and so no fuel (or premixed lubricant) will be going to the rotors?
 
Any thoughts on this ?
 
PS I know generally most rotary drivers don\'t tend to have their foot off the throttle for long - so maybe a non issue :Giggle

[Will66]

Interesting one, however according to the OBDII outputs on my RX8, with a shut throttle the fuel injectors are still injecting a small amount of fuel so you should get sufficient lubrication.

[m1tch]

I guess its the same with 2 stroke dirt bikes when off throttle, I guess there would be resisdual oil left in the rotors and if nothing is being injected there won\'t be any petrol in there to act as a solvent to remove it.

Mitch suggests to fix this issue by simply going full throttle everywhere to ensure the most amount of lubricating oil is injected at all times - honest officer

[Will66]

Mitch suggests to fix this issue by simply going full throttle everywhere to ensure the most amount of lubricating oil is injected at all times - honest officer

And I approve this suggestion! :Giggle :burnout

[Grant Monkhouse]

You are supposed to blip the throttle occasionally on all premixed engines if coasting. Or shut off after going through the 1/4mile

[Will66]

Or you could dip the clutch and let it idle.

[Grant Monkhouse]

It won\'t drop down to idle speeds though. Ithink the best thing to do is not worry about it. I didn\'t. Used to be funny listening to the bangs and pops as I slowed down

[BenLewisMav]

It wont make a great deal of difference. You actually don\'t need internal oil lubrication, but the apex seals last a LOT longer with it. If you look at the old Mazda tech papers they did tests at how much oil to use to keep the seal tips at the ideal temperature (then sort of muffed it up with the early RX8\'s :/).

[Brett]

Or do what I did at the weekend and :censored::censored::censored::censored: up your % calculation of premix - Smells like about 5/1 at the moment!

[Grant Monkhouse]

Or do what I did at the weekend and :censored::censored::censored::censored: up your % calculation of premix - Smells like about 5/1 at the moment!

You must be seriously crap at maths!! What ratio should you be running? 100-1 or 125-1? I ran 125-1 on my fd but may go 100-1 along with my WI:)

[Brett]

100/1 - I reckon its actually 50/1 atm.......

[Grant Monkhouse]

Your rotors are going to be caboned up bad. Unless your spraying water in there?

[Prof]

I thought the same - must be some way of telling how much oil is too much, and how little is too little.  I searched for a long time and found lots of peoples findings - but nothing so nice as a graph / table or other derived data about oiling rates for the internals of the engine.
 
Oh - and you DO need the oil inside - it\'s what helps build the compression as well as providing lubrication for the seals - that\'s why it\'s so much harder to start a flooded engine and why people suggest squirting a bit of oil through the plug holes.

[Brett]

It\'ll be fine - I\'m going to either dilute it down a ton or drain it out and start again.

Tanks an odd shape so its hard to work out the exact capacity.

[Grizzly]

Oh - and you DO need the oil inside - it\'s what helps build the compression as well as providing lubrication for the seals - that\'s why it\'s so much harder to start a flooded engine and why people suggest squirting a bit of oil through the plug holes.

Sometimes you get the Impression that due to only the Apex seals being oiled (on the leading edge) the low rpm Compression/starting is the main reason for the oil, there are a few reasons i say that, the temp normal engine oil works at will be massively exceeded inside the combustion chamber (so it will only have an effect from the Oiler to the Ignition point i.e. the compression part of the cycle, like it was almost planned like that and then you have the added problem of deposits on and around the Apex seal/Groove, then as the revs go up the Apex seal uses its own weight to seal as the centrifugal force often Exceeds the Pressure the Spring Exerts.

Does anyone remember the Hurley Rotor mod? (they drilled small holes through the bottom of the Apex seal groove into the Oil chamber) all this did was make it smoky and introduced carbon back into the Oil system. I only saw it done on 1 motor, its kind of like using too strong corner seal springs, looks good on paper but in Practice causes you more problems that is solves.

BTW you can usually tell if you have added too much 2 stroke oil as it will Smoke like an old lawn mower all the time If you use Synthetic 2 stroke oil I’m told (not checked this out myself) that it doesn\'t drop the Octane Level at all. A fun one to try is Castor oil based 2 stroke oil smells really nice.