Carb Icing and Pro FST.

It's come to that time of year again! The morning commute was like russian roulette at roundabouts. Would it or wouldn't it pull away

I have ran out of FST and seem to remember someone (probably YC) mention that FST is basically glorified isopropolol alcohol.
Being a cheapskate does the mighty org think that isopropolol would work and not cause any engine damage and if so how much per tankful?

It seems to be about a fifth of the price of FST!

[Dave20046]

Yeah i remember the same thread, sounds about right. If you get stuck without it again though you could put some high octane fuel in the tank.

I normally just run Higher octane fuel this time of year. There are no benignity in power of the engine as the SV does not have a knock sensor, but you will see a little better fuel economy which will cancel out the initial high price. The bonus here is that the carbs see less icing due to the additives that they add to the fuel companies 'super' unleaded, of which in my experience shell is the most reliable.
Being the dull man that I can sometimes be I spent alot of time experementing with this over 'simliar' long distants trips, getting 10-20 miles extra in a tank. Though remember you can add another 10-20 miles in tank range simply by following some rules like tuck in, keep below 7k and stuff like that. After all the SV makes most of its peak power at 8k anyway and I don't excatly hang about most days.

[embee]

Isopropyl alcohol will do the job, though its main effect is dealing with any water in the fuel which isn't really what causes most carb icing.

The light aero industry did a lot of work on the subject, and an extract from a GASCo document says
"We have discussed the fuel additive issue with a technical expert at Shell but that company does not market EGME either as a constituent of avgas or as an additive. It does market isopropyl alcohol (IPA) as an additive for both jet fuel and avgas , but this is intended to deal with the potential for water contained within fuel (there is usually some) from forming ice crystals when aircraft are operated at temperatures a good deal below freezing. IPA is not offered as a solution for carburettor icing."

Having said that, it does in practice seem to help a lot with carb icing generally, possibly by attaching to airborne water before it gets chance to freeze, but I'm guessing on this.

IPA is available on your favourite online auction site at very reasonable prices (c.£8 for 5L), though p&p and possible hazardous handling charges do add up.

I believe 1-2% is the recommended dose rate, which means somewhere round 250ml per tankful of fuel, so a 5L can will treat 20 SV tanks or around 3000mls worth.

HTH

Brilliant, thanks for the replies

[Dave20046]

There's also a great video of carb icing happening on youtube, it was posted on here - can't find it though

I have always advocated the use of super unleaded fuels e.g. shell V-power etc for winter riding in carb'd bikes. However, its getting very expensive now, if you can find a cheap supply (shouldnt be hard!) of I{A then you stand to save alot of money over the super unleaded options on the forecourt. I figured, for me, it was cheaper to use V-power than PRO-FST, although I suspect I could sneak / purchase a bottle of IPA from the chem department for my private use. 2.5 litres shouldnt cost any more than one bottle of PRO FST!