Jet Jon conversion cavitation

[wlockerb]

Just got back from a successful river trip guys. Clocked it at 25 mph with 2 people weighing around 225. Runs the same speed at half throttle though. Checked the plugs and she running pretty rich. Need to rejet the top end down a bit and see if I can get some more out of her. Had the top end mixture screw leaned all the way out and still a very dark brown insulator. Also, won't get on plane with just me in it due to cavitation. Need to either move my seat forward or figure something else out. But it was great with 2 people! Honestly, I am only using it for setting lines and you need 2 for that job anyway. Think the issue with 1 person is an issue I can fix with the spoon or a weight distribution issue?

 

[Ranchero50]

I thought you ran the screw in to lean it out.

Per the cavitation, extend your spoon out to the old marks.

Half throttle speed the same as full throttle, does the engine rev higher or sound 'funny'?

 

[wlockerb]

You think just elongating what I have will solve my cavitations issues? Why would it be fine with someone on the front and then be back to cavitating with just me?

Yeah, I did run the screw all the way in and the more I leaned it out the better it performed but It still bottomed out. I would call it a bog when I go full throttle. Just gets deeper sounding. Doesn't really sound like an rpm increase and as I said the plug is a very dark brown but not black like I would expect. The carb is an aftermarket mod. Its an sbn 44 and I guessed on the jets based on reading another forum. 2.0 needle and seat with 80 gram spring, 115 pilot jet, and 145 high speed jet. Think I may be a bit rich on both ends but I just bought 3 jets for each in 2.5 increments.

Also, I went to a 15 degree prop from stock so I am thinking about going to a 21 to get some speed back if I don't get the desired results from jetting.