Honda 150 four stroke problems???

Thoughts in the early morning. Totalizer wrong, suggests a possible restriction, hence not reaching WOT at full mechanical throttle position, engine sounds OK, really shouldn't but if the Tach shows full WOT RPMs, maybe the sound is fooling the ears....

Two problems... Restriction in mechanical flow device (assuming you have one of those turbine things and you're not pulling a signal from the engine computer) and bad Tach meter or input to the Tach...

It looks/sounds like its at WOT, but it's really not. Hence lower speed through the water and prop isn't slipping.

Just my .02cw.

Charlie
 
Robert,

Dirty injectors, bad fuel, loose or corroded tachometer connections, etc.  When you finally get this figured out you should focus on getting your boat propped correctly.  Being over propped can cause significant damage to your engine, your dealer should point this out.  Even if you putt around at 3500 rpm all day, you’re lugging that engine.  Lugging puts excess fuel in the combustion chamber, that fuel migrates to the crankcase where it contaminates your oil.  Long term over propping can and will cause premature engine failure.

My 25 came with a 19 pitch 3 blade prop; I could only make 5300 rpm at WOT.  After 3 prop changes I eventually ended up with 14 pitch 3 blade 15 1/8” diameter mercury Inertia stainless.  Now I’m able to hit 6200 RMP, mid range MAX RPM for my Mercury.  

You live in Florida, land of the Prop Gods.  No kidding, these guys helped me out tremendously.  Says on the web site that for a fee they will come to you and let you try different props;  their advice is free.  Talking with them on the phone and after doing a Prop Slip test their suggestion was right on.

http://www.propgods.com/Content2/Default.aspx

 

Good luck,

 
 
I'm having this same problem and mine started on one trip. I ran my c-dory 25 with a 150 hard for over an hour 5200 rpms or so going about 20 +knots then coming back it seemed I wasn't getting the speed I should have but I didn't really pay attention. The next day i was getting 14knots at 4900 rpm...way off base...I put a new prop on and no difference
The boat seems to run good until about 4200 rpms when something kicks in and I can hear a change in the motor but running it up to 4900 rpms gives me one knot more boat speed then running at 4200. At 5300 I'm barely making 18 knots. I do have a heavy loaded boat but this is not right. It feels like I am towing a huge log around. I doubt my brand new prop could be the problem????I'm using a 16 by 13 3 bladed aluminum prop????
Something happened that day?????
I need to fix it any thoughts.
I had a service done...new plugs and adjust the values but that did nothing either
 
I'm having this same problem and mine started on one trip. I ran my c-dory 25 with a 150 hard for over an hour 5200 rpms or so going about 20 +knots then coming back it seemed I wasn't getting the speed I should have but I didn't really pay attention. The next day i was getting 14knots at 4900 rpm...way off base...I put a new prop on and no difference
The boat seems to run good until about 4200 rpms when something kicks in and I can hear a change in the motor but running it up to 4900 rpms gives me one knot more boat speed then running at 4200. At 5300 I'm barely making 18 knots. I do have a heavy loaded boat but this is not right. It feels like I am towing a huge log around. I doubt my brand new prop could be the problem????I'm using a 16 by 13 3 bladed aluminum prop????
Something happened that day?????
I need to fix it any thoughts.
I had a service done...new plugs and adjust the values but that did nothing either
 
Two comments, for what they're worth. First, a Honda 150 changes the valve timing at ~4000 rpm to increase the upper end power. The Honda 135 doesn't and is rated at 15 HP lower.

Next, a C-Dory 25 is sensitive to weight. When Journey On is packed for a 3 day trip, it'll go 25 knts (on smooooth water.) When Judy packs that boat for a couple of months, I'm lucky to get 17-20 knts. Especially if there's a lot of sea. It figures because when you're loaded, you've got a lot more boat to shove up out of the water.

So, if you've got the boat packed, you may be doing the best that boat can without re-pitching the prop. Even then you'll be going slower. We're traveling at 7 knts @2400 rpm, cause gas is $5.50 in Canada. 4 mpg vs 2 mpg.

Boris
 
thank you for your input...I have been running this boat for 7 years so I know something is wrong.
My rpm/speed when I am on the boat alone is
3000 rpm 8knts
3800 13knts
4200 14.5
4800 17
5500 20
5900 23

boat loaded seven people
2900 7
3500 9
3700 12
4200 13.5
4900 14.8
5600 18


it seems to me that the lower rpm/speed is not bad but once that VTech? kicks in around 4200 I get nothing out of it....
it feels like the prop is slipping but I put a new one on and it didn't help
 
Well, if we're doing numbers, we've been running Journey On for 9 years. And that data looks normal to me.

& people is a good load. We've had 3 adults and 2 kids on board, and that slowed things down considerably. BTW, how does one get 7 people on a C-dory 25?

Boris
 
Seems to me that the point where things start changing and slowing down between the two is the very same point at which the boat would normally climb onto a plane.

Maybe it just can't (or barely) get on plane with 7 people aboard? Would also explain the prop slip, too.

Just a thought.
 
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