I wouldn't do that.. You'll just end up ruining an almost impossible to replace motor.. If you're gonna hot rod it, i'd get a cheap briggs 5 horse to build..
adding a mikuni will most likely just end up slowing you down.. You'll play hell getting the rite jets in it, and setup to run like it should.. Then once ya do, it really is no great improvement.. The engine is only limitied by it's valve train and ignition system and stuff..
It will flow a little more air, But once the engine is wound tight, it won't pull any more air than the stock carb, as the engine itself hits a wall...
The crank shafts in these motors do not seam to be very hard material.. I have seen PLENTY of these motors with a rod hole in the side of the block, and COUNTLESS MOTORS with SO MUCH rod knock, that the rod cap bolts are loose, and you can SEE THE UNDER SIZE in the crank with your eyeball...
tecumseh small blocks have a really light weight and light duty cam shaft and more than one of THOSE have broken in history..
Tecumseh parts have dried up and pistons, rings, valves, are all next to impossible to buy without a FAT bank account..
It's just a tiny little motor with no torque.. If you build the living piss out of it running on alcohol, it's STILL only going to have SO much power.. :shrug:
But it will destroy itself forever in no time.. TRYING to make the power a 5 horse briggs can produce with no oil in the crank case...
That machine although it's a tawian jobber, is REALLY CHERRY as far as old minibikes go.. I would just let it be what it is,, and find another bike to wreck.. OR AT THE VERY LEAST, show the Tecumseh some respect, and shelf it, or drive it like it's supposed to be...
Otherwise, you are basically saying
'WOW look how nice this 1940 Lincoln Zephyr is..
hmy: Original flathead V-TWELVE and all... I'm gonna throw 3 Holley 4 barrels on it, and make a mud truck"
:shrug:
