Four Stroke Carb Position
 

:D I have been modifying the manifolds on my various Four Stroke motors to simulate the method used on all Laser Engines. I have never understood why one needs to have a sharp bend bringing the carb down behind the cylinder. It becomes inaccessible and in the hottest place. All my tuning experience on racing cars and motorcycles tells me to have the straightest path from carb to inlet valve.
Can anyone explain why Four Strokes are designed this way apart from bringing the carb up to tank centre when inverted?
By machining a short stub manifold, with the same bore as the original, I place my carbs straight on the head. Usually coming out just at the rear of the cowl on side mounted installations. Easy to finger choke, easy to set the slow needle and appear to run without any problems, probably slightly more power at top rpm. One of my engines is the RCV 58, a good engine now even better!

RE: Four Stroke Carb Position
 

Well engine man, my guess would be that any engine that a manufacturer sells must be widely useable. Looking at your install provides you,on that plane, an easy choke and added rpms. However I could not use the same settup in one of my planes because this or that but both your plane and mine with work with the carb on the tube bent behind the cyl. I too enjoy backyard enginering my own parts and settups and thats a good tip you got there. Piper

RE: Four Stroke Carb Position
 

I accept that there are installations where the carb has to be down behind the engine, but for most planes, and I have built quite a few, there is no need. I would like the engine maker to offer an option so that I dont have to make the parts for my pals. I have just fitted a Laser 80 to my Beat-On and this has the carb underneath the cowl, driven by a miniature servo mounted just behind it. Inverted engine inside the nice cowl. Had to fit baffles to direct the air over the cylinder. Carb is easy to get at in this installation, not that a Laser ever needs adjustment after the initial run-in and tweak!