One of my friend has previously run his mower on Acetone, without any alterations. (He worked in the Fibreglass trade at the time, & so got it free)
Apparently it gave no problems - though it may have run at slightly lower power, he didn't find it noticable.
I'd cetrain recommend draining the tank (and running dry)when it's not in use. E85 is tough on seals not designed for it - but for short term use in cheap engines... give it a go!
