Has anyone heard of cleaning the carbs by dumping a half bottle of high percentage alcohol (like isopropyl) in a full tank of gas and running it hard on the freeway. I was told this by my uncle who has rode motorcycles his whole life, but I just wanted to see if anybody else has tried this and if it worked.

Never heard of it, but if it works, great!    Porbably, only done in low compression engines.  I wonder if it's like the 'pour-water-down-the four-barrel to-burn-off-the-carbon-deposites' for cars?

I don't see why it wouldn't work, alcohol will desolve anything that gasoline won't.  Actually one of the main concerns regarding converting an engine to run on an alcohol fuel is it will do such a good job at cleaning all the junk and deposits left behind from the gasoline that it could possibly clog the fuel system. 

I would suggest using ethanol because your fuel system is already designed to handle it.  Other alcohols can attack various rubbers, plastics, and metals over time, but once and a while shouldn't hurt.  Compression ratio isn't a problem because the alcohol will actually increase the octane rating of the fuel.  Be careful with how much you add, it will lower the ideal air/fuel ratio of the gas making it run leaner.  All modern engines in the US are rated to run on up to 10% ethanol and usually can handle slightly higher concentrations, so as long as you don't go nuts I'm sure you won't have any problems.

How frequently do carbs need to be cleaned? If I'm buying a used late-90s era GS (pretty likely to happen soon) would it be a good idea to run some seafoam through it, or should I only use one of those cleaners if I'm having problems with it? In short, should carb cleaning be considered regular maintenence?

g5

It might pick up any water you have in the tank, but that's about it.  If you have a carb problem disassemble, clean, and inspect.  As a general rule, carburetor maintenance consists of keeping the fuel filter clean, checking the float height once in a while, and fiddling with the idle RPM.  You should not need to run all kinds of cleaners through them on a regular basis to maintain performance, as long as you keep your fuel clean.

I hear that liberal amounts of alcohol will clean out the rider....

Quote from: Egaeus on May 07, 2006, 06:48:10 PM
I hear that liberal amounts of alcohol will clean out the rider....

I can attest to both.  Regarding the carbs, here's my '92 carbs after running 85% ethanol for a while:


No cleaning done on my part, unless you count running ethanol through for a few months.

img, not image

However, that is one clean-looking carburetor.  Mine didn't look that clean after an hour in B-12.

E85 is awesome... this is another reason why we should all use it instead of gasoline