I'm building a surface drive with a 16hp clone (420cc) and was wondering what prop to go with? Seems most of the motors this size are long tails and running sub-surface props so I'm having a hard time finding the right surface piercing. The gear ratio I was going to shoot for was 1.5-1. Boat is a 1436 with minimal gear, me and a dog. Any ideas for me?

Thanks for the help.

Im going with a Hill Marine 10x8 on an almost identical build.

Mag10

The 16hp Dixie SD runs a 11X10 I don't know how they are geared but that's what I got for my SD build.

I just finished a homemade surface drive with that motor. I've done some stuff to the motor. Added a mikuni carb, high lift cam, and stiffer valve springs with a high flow exhaust. Anyway Im running a 9x8 long tail prop right now on a 1.4:1 gear ratio and It's a little small. The motor will run about 4600 rpms wide open on my 1440 so I'm thinking about going to 10x10. I think 10x9 would be perfect but I don't know who makes one that size. If you don't do much to the engine i think that 9x8 is just about right. I'm not sure how much of an advantage it is to have a true surface drive prop but it does pretty well.

Interested in what prop sizes you guys settle on as my next build is going to be a 16hp duromax also. Cheapest, highest hp engine I know of at this time. Good luck to all and hope you guys are spot on when you finally get some water time.

I'm currently building the same thing and have a 11x10 on the way. Gearing is 1:1.5 so I hope the engine can spin it.

R1ley what speeds you getting out of that engine? Which one of those mods made the biggest difference?

Anyway before I ever even ran the motor I had already removed the governor and changed to a high lift cam and the mikuni carb so I can't compare its performance with those mods to anything before it. So this season I had the mikuni and cam but I hadn't changed out the valve springs to stiffer ones or put a high flow exhaust on and the motor wouldn't go over 4100 rpms and my max speed with two people and a dog and gear was about 17 and with one person and dog about 20. It was sounding bad on the high end so I talked to a guy who builds them for racing go karts and he said the valves were probably floating so I got those springs and put on the exhaust and it seemed to make a big difference. I hit 24 mph at 4600 rpms on the gps by myself the one time I've ran it since then but it was just me and the dog so I can't tell you how much of a difference it made for a heavier load. . But thats where I'm at right now. I would just say that your probably going to want to remove the governor first and when you do that you need to go with some stiffer springs ($20). Then find a 32-34mm mikuni on ebay or something (i got mine for $60) and build an exhaust (about $20). You will have to get one of the carb adapters to attach the mikuni which is about $35 i think. Those are all pretty cheap and then when you want to put in another $150 get a cam. Check out affordablegokarts.com, parsonsracingengines.com, and nrracing.com. Everything they have for the honda gx390 will work on these motors.

You guys let me know how those 11x10 props work though. I want to change to something bigger this summer.

I put mine on last night and hope to get everything wrapped up in the next week or so. I'll start a new thread and post some pics of my setup.

My 23 runs a 11x10 it might be to much for the 16?