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To all
I have a mc91 and wanted to know what it would take to run alky in it? what kind of alky to use? what mods need to be done? any help would be great
thanx

Hi Paul-
You'll have to adjust the timing a little bit and find an alky specific carb as a standard gas carb cannot flow the volume of fuel needed. Some folks swear by the factory McCulloch 'double-pumper' alky carbs, but I prefer the Tillotson for ease of use and parts availability. You can run a single or dual HL or a single HR carb. The HR is similar in size to the original but will you will have to find an adapter plate or modify the factory intake to accept the carb (instructions are available on this site)

Figure you'll burn about twice as much methanol compared to regular gas. Also, you'll need to purge the motor using a gas/oil mixture after each track day as the methanol is highly corrosive and will turn the internals into swiss cheese if let set too long.

On the up side, it really peps up a motor (20% gain in HP) and helps it run substantially cooler than with regular gas.

Here is a link to VP Racing fuels:
http://vpracingfuels.com/fuels_spec.asp

Regards,
Dan

The cooler combustion temp. of methanol is what allows running a higher compression ratio. If you don't raise the stock compression ratio when using methanol you're not going to see much if any increase in power. The major performance gain seen from methanol use is between 12% to 15% more torque on the bottom end thru the mid range than racing gas. Top end power wise, it's about the same as racing gas. A slightly colder heat range spark plug is also required. Racing plugs designed for 2 cycles work the best. On a really hot day you may encounter vapor lock when restarting the engine. It's prudent to not let your kart sit out in the direct sunlight on really hot days. I got reminded firsthand of that again yesterday in the Nevada high desert around 4000+ ft. and 97 degrees while trying to purge the methanol out of four still hot Mcculloch 101s.