Have heard same thing too about E70. With a mixed petrol/E85 works fine but I´ve been lazy to change filling pistols while fuelling up 
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One fella took slice of his Almera´s cyl.head to hike compression, told that works better now. Maybe I´ll do that someday, brings just a bit of headache with the chain. Although have seen your postings about chain adjuster mods, so shouldn´t be impossible job. Or is there easy piston change option available?
