What did the spark plug look like? Ngk has a good plug gauge chart on their website
compare it to that and you can tell alot on how the motor is running. The thing
about that first tank of e-85 is that any crap or water in the tank is getting dragged
out all at once!! You should completely drain the tank and carb(of course hindsight)
and then fill up the tank and this goes for anything not just small motors and wether
it is Methanol or E-85 that you are switching over to. Put a half a teaspoon of some
two stroke oil in the plug hole and try your compression test and see if it goes up.
If You can't find the rebuild parts go ahead and run 2 stroke oil in the gas and you
can get a few more hours out of the motor, Pulling the head and cleaning the valves
and the top of the piston/ combustion chamber and plug when it starts running rough
from the oil build up is all that is needed. Probably start at 75:1 ratio and see if it can
get enough compression to run if not then 50:1 but not much more than that. If it
still has trouble starting on the 50:1 then pull the plug and put a bit in there and it
should start up and then run. I did that with a buddies club car he didn't have any
money to keep it running and the company said they weren't going to pay to rebuild
it, It had like 35psi in the low cylinder and I ran it at 50:1 and a year later that thing
is still going strong without even ever pulling the head. Since he loads it down with
all the tools and crap and the property is pretty big it gets hot enough and only needs
the plug cleaned up every 8-10 hours of running!!