So I got my Zilla running again today. 87 octane, 40:1. It ran away on me so I killed it.
I pulled the plug and was kicking it over and I felt air the left side engine cover. 

How bad is this?

Oh wow, shes running super lean with that air leak. Even without the air leak. The mixture is to lean. My weed whacker runs 40:1..

SMH -   

LOL
Oil ratio and jetting aren't interchangeable.
Oil ratio is also not responsible for fouled plugs, that falls on improper jetting.
If you're getting a leak in the case it's either from bad crank seals or a **** case.
If you can actually FEEL the air leak, you've got a serious problem (unless you're feeling air being moved by the flywheel).
Time for a leak down test and visual inspection...

seal can be changed with out tearing motor apart.

Quote from: Buckeye513 on August 15, 2013, 06:06:20 pm

Terrible!!!! You're running 87 octane pump gas at 40:1!!! Just awful!!

I had 93 at a 32:1 and it just kept fouling the plug. Some googling around recommended trying 40:1 

Fouling plugs is a jetting issue.  Don't try to compensate by changing your fuel mixture.

Edit** Oops, i see Tex already said this.

Many of us are running between 20:1-32:1. Don't hear of any one fouling plugs when their jetting is right. I'm running 32:1 and haven't fouled a plug in 20 hours of run time.

Yes, we're serious.

Oil isn't what fouls the plug up, it's the carbon residue from improper fuel combustion.
Remember that carbon is a type of conductor (they use it for brushes on electric motors), and you're essentially coating the porcelain insulator with it.
Build up that carbon residue enough and the spark will short out at the base of the insulator instead of jumping the gap...hence a fouled plug.
Burning oil doesn't create any more carbon residue than fuel does, unless there's no more oxygen to burn (fuel mixture too rich).
If jetted correctly and running, the spark plug will be hot enough to burn any oil trying to short the plug out regardless of oil ratio.
The practical limit to oil mix ratio is probably like 5:1 to 10:1, I dunno, it all depends on how long you run it at full throttle.
That kind of oil ratio isn't good for cruising around with your grandmother.

Q2W...you're almost right.
Gas does cool the engine, not oil....no question there.
But, if you're using enough gas for proper jetting (ie rich of stoich, 11:1 or whatever), there will be enough fuel to cool it.
You'll need some huge jets if you're running something stupid heavy like a 10:1 ratio, but as long as the AIR:FUEL ratio stays the same, the fuel:oil ratio won't matter.
If you were to up the oil ratio to 10:1 after jetting your bike to 32:1, then yeah, there won't be enough fuel, it'll run lean, and you'll destroy the piston, because that extra oil changed the air:fuel ratio.
Only so much liquid will pass through a jet, so if you're jetted for pure fuel (for simplicity's sake) and then go with a 1:1 fuel:oil ratio, it will be the same effect as giving the engine half as much fuel.
Change the jet out for something that flows twice as much and you'll be back to the same air:fuel ratio, but with all of that oil mixed in with it.

Something else to consider...when a bike is run on methanol, the air:fuel ratio changes and you're putting in something like 15-20% more fuel to maintain rich of stoich.
That means the engine is seeing 15-20% more oil too, if you kept the same ratio that you used with race gas.
Most of the time though, the oil ratio used by alky 2-strokes is heavy, like a 20:1 ratio.
On top of the heavier ratio, there's also more oil going into the engine because the jets are bigger too.
Those engines are probably seeing the equivalent of a race fuel engine mixed at 15:1, but I'm too lazy to do the exact math on that.

stoich for methanol is 5:1. i run 24:1 with VP M1 mixed with klotz benol. I purge out the methanol with pump gas mixed with 2 stroke marine oil at 24:1. tha. spray fogging oil in.