iame k71 question

Not hard if you know what your doing, a lot of port work, some head work. but they are not gonna run with a reed or rotary open and they are limited somewhat how big they can be built as compared to starting with a 125. They do get a big weight break in UAS being a piston port for good reason but you would need a jockey sized driver to take advantage of it. Build an open out of it, put it on nitrous, hit the track at under 300 lbs and on some tracks it might be interesting to see what it will do. Jon
 
I believe a Rotary valve engine is always going to put out the most horsepower, all things being equal. I believe, the only reason the rotaries and the Reed valve's are close to equal is because the Reed valve's come with bigger carbs. The K71 comes with a small carb as you know. Put a big carb on the K71, up the compression ratio to what the Reed valves have and equalized the porting, and you have something else. I have no idea for sure if the K71 would then match the Reed valve engine with these improvements, but I have to believe it would be close.

The Reed valve engine only exists today because Margay built the LMR. (Lumello + Margay + Reed valve) It wasn't a great engine horsepower wise, and the Italians surpassed it very easily with the K55. If the ruling bodies had given it a class of its own, like they did with the Mc's and the Yamaha, it would be with us today. Why the ruling bodies didn't support this American made engine is beyond me.

The class designation, McCullough, was thought to be keeping other engine makers from entering karting. They changed the designation to American Reed. The thinking was that other chainsaw manufacturers would join in. But what happened was Margay built a free air reed valve with the same size carb as the McCullough. Obviously the LMR was faster than the McCullough, so they changed the class designation back to McCullough. This left the LMR hanging out there by itself. IKF, in its infinite wisdom, created a class in which the LMR could race, but they left the designation of its class open to other competitors. Russell karting and the Italians jumped on this opportunity with the K55.

Comments compliments criticisms and questions always welcome.
If the data does not support the theory, get a new theory.(Al Nunley)
 
Don't mean to be a buzz kill, but a full open K-71 is going to cost 2K to build and is not going to beat a good stock Reedjet. If the weight break for a piston port is still a temptation, why not start with a used JICA motor ? That would get you a good start and you could tweek it a bit if needed
George Clausen
 
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