Aircooled Sudam

Hi guys and girls, picking up a Sudam at the weekend, quite excited, non-existent over here and I’ve been after a DD 125 with none of the messy bits like balance shafts, CDI boxes and power valves!

Anyhow, I’m after any advice/info of all and any kind related to the Sudam. There is next to none on the t’interwebs so im hoping you guys can help: Max revs? Rebuild times? Carb settings? Flex length? Preferred exhaust? Air/Water differences? Etc etc!

I do have 2 more precise questions, whats involved in converting them to run Methanol? And is there ‘best’ carb size? I’m intending on sticking an X30 Tryton/Tilly on it.

Thanks for any help, Thomas…

At the least you’ll add a second fuel pump and plate to the carb to deliver the extra fuel. Ideally you’ll go with a larger carb to make room for the extra fuel to atomize in the venturi. Anything from 30-34mm… or 2x24 if you want to get really crazy.

Otherwise, you’re looking at a combination of increasing ignition advance and/or reducing cylinder head volume to raise compression.

I’ve seen lots of ‘bits of things’. A 34mm Mikuni seems to be a go to carb? But is that a Diaphragm or Float carb for a start?

As for ignition… I’ve seen variations of about 30° so I’m really not sure with that either! I’ve read gains of 3-4hp on Methanol so I’m really intrigued by it

In the US you mostly see Sudams that were modified and run on dirt ovals. Most of those seem to use the twin double pumper Tillotsons on methanol. Some guys still run them and they get with the program quite well.

You can make more power for sure, as much as 20% more, running lower temps.
Downsides are

Corrosive nature of Methanol with aluminum means you’ll have to run petrol though the engine it at the end of the day. Some people do it every weekend.
Higher compression in DD format can kill entry speed
Thirsty :slight_smile:

Love that you’re giving it a go though, doesn’t seem to get used much in Europe.

Here’s a thing of beauty for <$500

image

If you want to go full nuclear, ask @Mynameismcgyver about adding a little nitro.