1988 V20 with 225 Honda

jackman1939 · #1 07-26-2006, 04:38 PM

Finally got my new T-top made and installed on my boat. Took it out a few times. Boat used to go 44mph (with the old T-top), now it only goes 40mph. Gets about 2.5 miles per gallon. Seems to me that it should go faster than that. I have to keep the trim very low - when I try to raise it, the boat porpoises a lot. I installed one of those anti porpoise things on the motor, but that didn't really help.
HELP !

bigshrimpin · #2 07-26-2006, 05:05 PM

Yikes . . . You'll need trim tabs and wedges to get the bow down. I'd recommend selling the Honda and getting different motor. 2.5mpg is horrible for a four stroke . . . I got better fuel economy with my 1988 Yamaha 200hp (right around 3mpg . . . always better than 2.5 even in the worst conditions).

What prop are you spinning? where does the cavitation plate line up in relation to the bottom of the hull?

reelapeelin · #3 07-27-2006, 12:28 AM

Yeah, Jackman...I fear BS is right...something's basicly wrong...I'm gettin' 42 mph outta my Honda 150...your 225 oughtta be SCREAMIN'!! :o....

Pretty sure ya need trim-tabs to start with...then 3 questions:

What's Honda say MAX RPMs are on your motor?

What is your's maxin' out at?

What prop ya got?

BS makes a good point...the 225 is probably too HEAVY for a V-20 to begin with, so if tabs and a new prop don't get ya straightened out, ya might wanna start thinkin' another motor...good news is, ya shouldn't have any probs sellin' that 225 ;) ...

msbhammer · #4 07-27-2006, 12:32 AM

Post pics. of the motor and hard top. ::)

jackman1939 · #5 08-12-2006, 01:37 PM

Thanks for all your inputs guys! When I first got the boat, it looked like it was sitting low in the back. The 1st thing I did was move the batteries up front (put them in the 1st floor compartment way up front). Also looked like the engine was mounted too high on the transom. I lowered it 2" - that's as low as it could go.
The prop is a SS Honda 14 1/4" X 17 four blade. Call the prop experts and they said it should be ok. Top speed is 41 mph (GPS) at 5300 rpm. The dealer says top RPM for the engine is around 6200. I thought about that, and assumed if I got a prop with less pitch, I would get more rmps, but slower speed. Am I right about that?
I do notice that the boat leans to the left when I am moving out. Also noticed that when I look at the water coming out from under the boat (where the transom meets the water - and the boat is moving out), I see some spray from the transducer (which is normal), but I see little sprays all along the bottom. Is that normal? I would think that that area would be flat and undisturbed. Not sure if I explained that correctly - if not, let me know and I will clarify. The bottom of the boat is painted black.
The bow of the boat does not ride high, seems to ride like it should (judging by other boats that I had).
I can post some pictures, but I don't know how to do that. Can you tell me how?
Just checked the cavitation plate, it is 1/2" below the bottom of the boat.
The boat and motor seem to run fine, it's just that I think it should go faster and get better mileage.
thanks again!
Jack

Airslot · #6 08-12-2006, 03:33 PM

Are you giving us the WOT of 5300 trimmed out, or motor trimmed down? I still think that you should be able to twist a 19 or 21 all the way to 6200 w/ that 225 on a V-20. The cavitation plate should be even or slightly above the hull bottom, or higher if the prop will hold on. After checking, your gear ration is 1.86:1, virtually identical to my Merc 150. I'm turning the same 17p prop to 5500 through the same gears. Something ain't right with that 225.

Airslot

C YENSEN · #7 08-12-2006, 04:08 PM

SOUNDS LIKE THAT BIG MOTOR IS JUST A LITTLE HEAVY FOR THE V20 ;)

jackman1939 · #8 08-12-2006, 06:25 PM

I keep thinking something isn't right, but I don't know what!! I mean, the thing runs great, and I love it for fishing, but still am wondering what's up with it.
I assume WOT means Wide Open Throttle - when I floor it, it goes 41 mph - I adjust the tilt up and down some and I get 5300 max rpm and 41 mph. Just thought of something: when I push the throttle all the way forward, it bottoms out on the console. Maybe the trhottle has some adjustments that could be made so it could go further?? Don't know, never looked into it - maybe the throttle being pushed all the way forward does not necessarily mean that the motor is wide open.??? Any suggestions on checking that? Guess I could take off the cover and see what's going on under the hood when the throttle is moved.
Sounds like I could move (remount) the engine up 1" to get the cavitation plate 1/4" above the bottom of the boat.
I am really frustrated with this outfit. The guy I bought it from said it does 55 mph! Never saw that - guess I should have tried it out in the water before I bought it.
Oh, well - maybe one of you experts and figure out what's going on.
thanks again,
Jack

Airslot · #9 08-13-2006, 10:54 AM

Pull the cowl and the air silencer off the front of the motor and see if the butterflies in the throttle body are opeing all the way. Could well be the problem right there.

Airslot

Seacrets · #10 08-13-2006, 09:12 PM

I run a 150 hp Merc with a 17" pitch prop (14 1/2" diameter) and I'm running 41 mph. *I really think at least part of your problem is prop. *When you bought it did the previous owner switch out the prop?