only problem you may have with a victa mower is fitting a clutch / sprocket because of the tapered shaft
regards jay
Hey guys a quick email around to local kart shops should get you a little conversion bush for the shaft
Another engine you could consider is a Kirby tecumseh 2 stroke engine which is period for the Kart.
Light and easy to tune beyond 3X original power output. I had one putting out over 12HP. It was competitive with a Yamaha racing engine that cost over a grand. We used to pay $10 to $25 for old mowers and wreck them for the motor. The weak part of the engines were the crankshafts and were often bent and the heat treating on the main journal was a bit hit and miss too. I suspect this is why there aren't many left around, combined with the fact that many lawnmower shop guy's didn't like them as the little exhaust bolts and inner studs would often break off, as they would corrode in the alloy, hence being turffed and despised for ever more!
They ran a needle roller top and bottom end and you did not have to press apart the crank to take the conrod off, (unlike a victa) the were a split design like a car engine. The cranks needed to be machined down to 3/4 of an inch (or 0.750") to fit a "Maxi torque" clutch and have a keyway cut also as the grub screw arrangement is nowhere good enough to hold on a Kart.
Just polish the rough edges off in the port areas and file them from round to square following the original angle of the holes and blend back into the port area (and then polish) under the port covers, leaving the centre bridge alone, just doing this will lift the power from ~4hp to ~8Hp
providing you fit a larger carby. A tilliston HL30 with a 7/8" bore and a home brew manifold will do the trick! ($~300 for that alone though!)
Even just fit a bigger carby off a victa or a pope rotary valve engine, and get a "Flymo" muffler and chop the baffles out will give you heaps of "fun power" suggest running an 11 tooth sprocket on the clutch (#35 pitch chain) and looking at those large rear wheels I'd go an 86 tooth driven gear. Just looking at the Kart, I reckon 8Hp would feel like a 1000!!!
All in all, what ever you do, have some fun, that's what Karting is all about!
John
P.S ol' Joe Brown on here has a couple of cheap Kirby engines, drop him a line. I bought a few off him for parts.
