I have been researching this for a while and cannot find anything definite. I build/run airboats and have decided to try to modify an Echo 23.6cc tree pruner engine to use the existing clutch with a propeller. I have already cut down the clutch housing to expose the clutch shaft and tapped the shaft (was a 1/4" square) to a 5/16x24. It worked perfect, leaving a perfect tap and threads. I have 2 very thick aluminum washers (about 3/16" thick each) to use with it, but I'm a little leary to fire this baby up for fear of the clutch shaft possibly failing!! Has anyone tried this yet? I figure the clutch shaft and clutchs themselves should be pretty strong, being as it was on a tree pruner...or pole saw some may call it. If anyone has tried this, or have any ideas before I temp fate, I would really appreciate it!!

Do not do this at all!!!! any slight imballance and it will fall apart and the thrust preasure will cause a problem.you need a prop adapter. You just need to know what the thread size is 5/16-24 or 8mmx1.0.

http://www.carrprecision.com/Pages/prod02.htm

I figured as much. I had posted same question on other site and I'm getting same answer [:'(] (It was worth a try). What propeller would work best with this 23.6cc motor? I'm looking at getting a 14x9 3-blade to lower COG, but don't know if it will be to small/large. Also, what size 2-blade would be good to start with? I have always ran nitro engines on my other airboats, so I'm not to familiar with prop sizes for gas.

my 23.6 is brand new.only have about 20 ozs through it,stock carb,cd ign(battery).i have the timing retarted to much right now so im going to advance it to 26 degrees BTDC and put a little bigger carb on it.anyway right now im turning a mas wood 16x6 at 7000.after im done and by what a few fellow pilots from rcu have told me it should turn about 7200 with a 18x6.mine weighs about 42 ozs RTF.Ken Lambert made my pitts muffler.

Thanks for the prop suggestion. I've ordered a 14x7 3-blade as a start. We'll see how the stock motor handles this and go from there. I trimmed all the metal away from the flywheel shroud (not off the flywheel itself yet) and stripped it down to the basic motor, and it turned out really good! I'll order a prop hub soon - I'm researching who has good price/quality and will give them a try.