I found this article about adding acetone to fuel on another forum - It might be worth a try. For metric using people it works out to about 2mL acetone per litre of fuel for a possible 25% increase in economy and a small increase in power. Imagine getting 250km from a tank of fuel in a FIZZER http://www.pureenergysystems.com/news/2005/03/17/6900069_Acetone/
If I remember right acetone will dissolve some plastics and the floats in the carbs are plastic so I would check that out first.
It does mention that in the article however so will petrol too. It appears that plastics that are petrol safe do not have a problem with acetone particularly in such a low percentage 0.2%. Apparently anything from 0.7ml to 2ml max will make some difference. (0.7ml/litre is 0.07%.