Thinking Back . . .

Thinking back on my problems with the TB22EC weed eater, I think adding Castor oil to the mix provided to much lubrication, too much slickness.  We know that Castor oil morphs into a longer molecule when heated and in fact gets slicker.  Also it burns at a higher temperature, and thus is not consumed in the combustion process.  Model airplane enthusiasts do not like the Castor oil as it leaves a mess to clean up.  But the mess means things are indeed getting lubricated.  Small price to pay.  It is the same lubricant used in WW-I airplane engines and is why you see the pilots with it all over their faces except where their goggles protect them.  Castor oil used as a lubricant is the same stuff mothers use to dose their kids with to improve their bowl movements.  It is said WW-I pilots did not have constipation problems!

Well not all of oil anyway is consumed.  But that is not a bad thing as the oil expelled also carries away some of the heat generated by the engine so it acts as a coolant.  Those are good things but maybe to much goodness for the engine or at least the piston rings.  So I will rein in my use of Castor oil in the mix.

MTD also says that the engine must absolutely have at least a 40:1 oil ratio.  A lot of folks and even little plastic bottles of oil say you can run on less oil.  And the oil is synthetic meaning among other things it has a lower temperature of combustion.  So in an effort to keep the power head clean with little or no oil residue, the lubricant is supposed to be consumed.  They advertise the oils as "ashless."  Not sure what that means but seems to indicate that the lubricant will be consumed and produce no untoward exhaust products.  A 40:1 ratio means at least 2.3 ounces of oil per gallon of fuel, so must avoid those little bottles of oil, use more not less.

Couple all of that with California emissions rules, the engines tend to run lean.  Lean burn so to speak and that leads to higher operating temperatures.  So we are at the mercy of California rules even though we are miles and miles away from California.  They have removed the slots from the ends of the fuel adjustments on the carbs.  I am inclined to use my Dremel and cut some slots so that I can tinker with the settings.  After all I have spare carbs I can use for this experiment.

At any rate the new weed eater is running just fine. Maybe a couple of tanks of fuel through it already; as it does edging, weed eating and blowing at least twice a week.  And I know for a fact the oil ratio is probably closer to 30:1 at the moment.  And by ear I can tell the engine is not overrunning RPM wise.  The fuel also has some gunk (that is what I call it) to keep the gas from going stale (turning into to much varnish).  The reason for that is the new one came with a packet of the stuff to add to the fuel.  So it has all the sweet stuff in it to make it go.

We shall see how long this one lasts.