Help propping Honda 20HP 4-stroke

[steelespike]

Re: Help propping Honda 20HP 4-stroke

My info says max rated rpm is 6,000.
These little 4 strokes must be carefully propped close to max rpm.
Get us a base line to work with.one light and one with typical load.Remind us of the prop size.

 

[ifishmuskie]

Re: Help propping Honda 20HP 4-stroke

I have a 20hp honda on my boat for the last 8 years. I had a 20hp evinrude on it before that. So i have seen what a 20hp can do with all different loads.

Something is wrong with your set up. The prop size and the boat weight you have should be able to go about 18mph with 2 people.

Is the motor at the right height? Is it a long shaft on a short shaft boat? Is the motor at the right trim angle? Put up a pic of the back of your boat if you can.

 

[ifishmuskie]

Re: Help propping Honda 20HP 4-stroke

maybe throttle linkage is not opening all the way. The motor has a rev limiter at 6000 rpm and i have never hit my limiter.

 

[SteveMFG_Oxford]

Re: Help propping Honda 20HP 4-stroke

Kinda late here but if its any help I have a 14.5 ft MFG Oxford with a Honda 20 PTT. Honda weighs 134 lbs according to what Ive read. It is propped with a 9.25 x 10" Solas prop and pushes the boat at 18 mph at 3/4 throttle, 23 mph WOT on calm water 1 person and gear aboard.

Note too that this is a long shaft engine on a short transom boat. It it were a short shaft it would do better yet. This a forward steering boat and of course the engine is a remote control unit.

See my thread for more info.

 

[xjma]

Re: Help propping Honda 20HP 4-stroke

Well before I could get on the boat with the tach and GPS someone borrowed it and destroyed the prop, so my brother bought an 8 pitch prop. Now with 2 people full throttle it will hit the rev limiter, so we're going for a 9 pitch. I GPSed it with just myself in the boat and got a little over 16 mph without hitting the rev limiter. We'll keep this 8pitch for when we're going to overload the boat or something. Thanx for the help everyone.

 

[sutor623]

Re: Help propping Honda 20HP 4-stroke

Well before I could get on the boat with the tach and GPS someone borrowed it and destroyed the prop,

Well that sounds like you were being a little over-generous there.