avgas/methanol

hi all this is maybe not a topic that will get many replies but as the only decent bikers forum about i thought id ask this question. i run a 175 2stroke for sandracing it runs a yz250 piston big reed block big carb etc etc however we have run the bike on a 50/50 mix of petrol/avgas due to the bikes comp but could anybody tell me what the difference is between avgas and methanol if there is any all help would be gratefully received cheers

The difference between Avgas and Methanol is that Avgas burns at a higher temperature to Methanol. Methanol is also a toxin to the body and to some materials e.g. aluminium. Methanol is a weak acid and can attack the oxide coating of the aluminium that protects it from corrosion. Avgas on the other hand, has a lower uniform vapor pressure than Methanol and normal petrol and this stops you getting vapor lock whilst the liquid turns into a gas whilst still in the combustion stage. Methanol is a good fuel to use for racing but not many people use it since it is a high-toxin. 10ml of Methanol will cause blindess whilst as little as 100ml will cause fatal death. Hope this helps.

Tim

Hi Robbie100,
Many of the bantam racers run Avgas, the advantage is the reliability factor! The Avgas burns slower than pump petrol, as a consequence there is more unburnt fuel about (you need to run a slightly bigger jet) this acts as a coolant to the engine. To assist with obtaining a little extra power it is also possible to run a slightly higher compression ratio to speed up the burn and advance the ignition about an extra 3 to 4 degrees over the settings for pump petrol. The Avgas is a controlled fuel as it is for light aircraft, this means the variation found with pump petrol is nothing like as great with Avgas, so your fuel settings are much more stable.
I advise the use of Avgas if you can get it, I will not run on pump petrol!
Hope that helps! do yourself a favour and stay away from Methanol, but if you race with us at any time then you are restricted to petrol and Avgas in the bantam racing rules.
Cheers
Alan