Quick Question on Honda 50hp

[jjohnson120]

I just bought a pontoon with a 2004 Honda 50hp. The motor has not been used very much and is in good condition. The previous owner let it set for awhile with old untreated gas. I had it out on the lake and it seemed to run ok, just a little rough at low RPM's, due to the bad gas I'm assuming. I did notice when I was out that at WOT or what should have been WOT the tach only showed 3100 RPM's but according to gps was running 21.5 MPH. After reading I notice that WOT is suppose to be 5,000 to 6,000 RPM's, so I'm curious if the anyone thinks the tach is not reading properly or I was legitimately only at 3100 RPM's due to bad gas?

Previous owner said he had speed at around 24mph but I honestly didn't know if 1900 RPM's respectively would make a 3mph or so difference. Any insight would be well appreciated.

 

[Wecanoe]

Re: Quick Question on Honda 50hp

I would suspect the prop pitch is incorrect for the application. I don't run a pontoon, but I do have a 50 hp Honda on my 16' Lund. You may be running as much as 13" pitch and what you need would be closer to an 11" or 10" pitch. If you can get a part number off your present prop, you should be able to get the pitch.

Changing prop pitch is alot like changing gear ratios in the rear end of a car or truck, except it's a lot cheaper! On my Jeep, I went from 28" tires to 34" tires -- about like taking my 50 off my Lund and putting it on a pontoon. I changed gear ratios from 3.07 to 4.56 -- about like going from a 13" pitch prop to a 10".

I'm still used to running a 2-cycle, but I would think 3100RPM at WOT would still be concidered lugging the engine -- just not as bad as on a 2-cycle. I'm sure someone will correct me if I'm wrong. . .

 

[jjohnson120]

Re: Quick Question on Honda 50hp

Alright I will for sure check on that. Do all Honda 50 HP motors come stock with the same prop? Reason I ask is because I know the owner said he changed it cause he chipped the other, and I'm wondering if he replaced it with something different.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

FYI I called the dealership while at work and they said if they remember correctly it should be 11 1/8 x 13 on the prop. I'm not sure exactly what those numbers mean but that may help someone answer my questions. I will confirm those number when I get home. Thanks in advance.

 

[Tig]

Re: Quick Question on Honda 50hp

Wecanoe is on the right track on prop sizing for Honda 50 on a toon.
I just wanted to comment on the RPM.
13" pitch. 2.08 gear ratio, 3100 RPM, estimate low slip (10%) and the speed I get is 16 MPH. Even with an unrealistic .01 slip, it's only 18 MPH.
Check the tach setup. I think it's set up wrong. I would guess that you are running in the 4000 RPM ball park.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

So do you think the tach was setup wrong from the factory? Cause essentially the boat is brand new cause the guy never used it cause he got sick so it's sat in storage and nothing has been modified. I looked at the prop and there are numbers but they are so faint I couldn't make out the last numbers so I'm not sure that it's even worth anything. My problem at the moment is that the key I had for it broke and I need to get a new one. No one around here can make one and the dealers act like I'm asking them an impossible question.

 

[Tig]

Re: Quick Question on Honda 50hp

I had the same experience with the key issue. There is a part number for it, but you have to figure that out because some dealer staff are not aware of this. Try looking here to see if you can figure out which key you have; http://marine.honda.com/pdf/accessories/Key_Switches_Key_Panels.pdf
Back to the prop. If I have a full load in my 15' boat, my BF50 with 13' pitch prop will struggle to get from 4000RPM to 4500 RPM. I think that's where you are stuck if you have a factory 13" pitch prop.
I'm not certain what brand of tach you have but as an example, here is a link to a Faria tach manual. http://faria-instruments.com/site_manuals/IS0012u.pdf It shows that the tach should be set to 6 pole for the Honda 50. If it's set wrong, you get the corresponding wrong reading. I'd hazard a guess that you are set for 8 pole and are really running 4133RPM ( = 3100RPM * 8 / 6 ) If you can get past 4500RPM the motor will come alive.

So the key to sorting this out is establishing a known starting point. Check the tach setting and have a prop shop verify the pitch of the prop. Just explain that you are sorting this out and want to know where you are at before you decide on buying a new prop. After that you can turn your attention to the issue of what bad gas may have done to the carbs.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

Well sounds like I have some more work ahead of me unfortunately. I did figure out the key code, so I think I should have that handled. On the tach issue, are you thinking it is hooked up wrong on the back of the tach? or at the motor level? I'm just trying to figure out where to start.

I guess I'm kind of disappointed now cause I sold my old boat cause I ran into problem after problem, so I bought this hoping for a fresh start and with how new it was and how little it was used I had high hopes. Unfortunately I don't have any leftover money to take it to get fixed cause at this point I'm pretty burnt out on fixing things.

 

[Tig]

Re: Quick Question on Honda 50hp

The tach change is done via a switch on the tach it's self. Nothing to do in the motor. On a Faria it's a rotary switch that can be checked and changed from the back. See the manual I linked. Tachs are pretty simple that way. I did have a generic tach I used to use for troubleshooting motors. It had a switch under the cover. But even that was clearly labeled inside.
No need to think about taking this anywhere yet, these are just a couple bugs. Once dealt with they are gone forever.
ID ing the prop shouldn't cost anything. It only takes a minute for a shop to check with a pitch block. They may even be able to repitch it down but I'm not sure they could get it down to an 11.
Honda's don't like old gas so get rid of that before you make any prop purchase decisions. If it starts and idles nice then it's a pretty good sign that the carbs are not fouled. Idle passages seem to be the most notorious for plugging. A bit of carb cleaner or seafoam wouldn't be a bad idea as a precaution.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

I appreciate all your help. After I posted I re-read that and noticed that it is just a switch so hopefully that's an easy fix. I have removed the old gas and filled it up with some quality Premium. I had thought about adding some seafoam as I have used that before in cars so I may give that a try and run it on the muffs in the driveway.

Once again, you've been very helpful and I really appreciate the words of wisdom.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

I pulled the tach off tonight and it was wrong. I switched it to what that manual said was correct because that is the brand, and it seems to be closer, but still at idle shows wrong for some reason. I have tried cleaning the carbs by spraying carb cleaner through them and the fuel hoses attached, but much more than that and I'm afraid of taking too much apart. This boat has turned into more than I wanted to mess with as it was supposed to be ready to go which was what I wanted because the last boat turned into a money pit and continual project. It was one of those boats I worked on more than I used. Unfortunately I had this boat out for 10 minutes and have worked on it at least 16 hours. Looks like it is time to sell and move away from boating.

 

[Tig]

Re: Quick Question on Honda 50hp

What did the tach show at idle?
As for working on the boat, I meter my time. I've had my current boat two years and I'm still fiddling with it when I want, but mostly using it. I finally made a prop change today. Now I'm trying to decide if I like the result.
Your setup is working OK, with room for improvement. Don't be in a rush. Summer is not the time to tear things apart. Mix up a batch of fuel with a healthy dose of seafoam and go boating. That counts as work/play. Soaking in seafoam is better than a blast from a can because it has a chance to loosen things up. IMO

 

[slats101]

Re: Quick Question on Honda 50hp

Hey JJohnson120,
Have some heart. Mr. Murphy comes to visit with all of us from time to time. I know it's frustrating to deal with issues, mechanical and other, when it was supposed to be "ready to rumble". Thats part of mechanical ownership of anything. If you have the funds to pay for the work, great, if not, you can get a lot of self satisfaction, and frustration, by doing it yourself. But don't give up the ship yet. Like Tig said, mix up some fuel, give it a drink of a cleaner, LUCAS or SEAFOAM, I like SEAFOAM best, and slice some water up!!! You just might be suprised at what you find. At least a little peace, even if you only drift........Remember, winners never quit, and quitters never win. Be of stout heart, me boy'o, and pull up your boot straps, stand tall, and ride that beast like you stole it!!!!! Trust your instincts, and see if you like the way she runs out, no matter what the numbers say on the tach. It's all about the fun, not the perfection of the state of being.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

The idle numbers looked like 1900, but would jump down when I gave it throttle and looked to be a lot more accurate even, though you could hear that when I gave it throttle the RPM's were increasing. As far as the Seafoam treatment goes that was going to be my last ditch effort before I get mad enough to sell or shell out the cash to get it fixed. Over the years I've messed with several dirtbikes and ATV's and feel somewhat confident with my skill to mess with things like that. I suppose it seems daunting having 3 carbs and kind of pushes me not to get overly involved other than with basics.

 

[Tig]

Re: Quick Question on Honda 50hp

While a perfect running machine is a beautiful thing, you have to balance that off against the thought that you are getting ready for play day, not race day. If it's cooling properly and running reliably then you are set to go. Take time to get to know the boat while the seafoam does it's thing.
A shop manual from Honda is a good investment for the future. There is negligible theory, but all set up procedures are in there.
As for multiple carbs, here was my $3 solution to setting them up. http://forums.iboats.com/showthread.php?t=395500 I'm very happy with the result.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

I will definitely check this out when I get home and can view the pictures. You've provided so much info I feel as though I owe you a candybar at the very least.

 

[jjohnson120]

Re: Quick Question on Honda 50hp

Added some seafoam to the gas and ran it awhile and still hasn't seemed to change anything. The throttle response hesitates even after warmed up and will sometimes even stall out. I've read that this may also be due to the carbs not being synchronized and to be careful cause the motor could be running lean.

 

[Wecanoe]

Re: Quick Question on Honda 50hp

Don't give up, yet. Once she's runnig good that 50 horse is an awesome motor! I did buy my '99 from a dealer "Yep, everything was gone through before we put it out on the floor (where it sat for over a year)". Wouldn't idle, ran poorly under throttle. Took it back and they DID go through it (rebuilt and sync'd carbs, replaced the fuel pump), and last year and this it starts right up, idles/trolls great and top end is good, too.

 

[MACHINE]

Re: Quick Question on Honda 50hp

are not some of the Hondas 1.83 gear ?? or so??

 

[jjohnson120]

Re: Quick Question on Honda 50hp

The problem now is having someone do this for me. I'm not that familiar with any the shops around here and the couple I'm aware of are backed up for a month and a half or I was told to stay away from. I thought I had a boat mechanic lined up that also does some minor work on the side for extra money, but unfortunately doesn't seem to want to return my calls. I have told several people I know what I need done so all I can hope for is that something comes along. I just hope I get to use the boat before the season is over.