Honda 50 2005 Running a little Rough

Hi All

My Honda 50 outboard started running just a little rough - not by much but when it usually runs smooth as silk I noticed it right away.

I have new gas filter and run a gas/water filter too. Regular oil change also.

I live in SC low country and have seen the commercial oystermen run Yamalube Combustion Chamber Cleaner thru their outboards.


Is this something I should do?

Anything else I can do? I don't want to damage/screw it up - I know how easy it is to do something like that

Honda dude are you out there - you sir have been very good to me in the past with your wisdom

thanks y'all
Simon - RLI01

First thing I would check is your plugs and spark on each wire. Next, is fuel delivery, main thing to check are your external fuel lines, bulb and internal lines. Make sure they all have tight clamps and your not sucking air, which can make your engine run "rough". If you have not replaced your fuel lines ever since 2005 IT IS TIME, bulb included.

Next, it looks like yours is Carbuerated, so I would then look to see if a float needle was stuck causing your issue, sometimes the little black plastic insert in the aluminum needle comes out, which causes the float to remain in the down position and not delivering fuel to the cylinder. New needles are like $20 on boats.net

http://www.boats.net/parts/search/Honda/Outboard Engine/2005/BF50A5 LRTA/parts.html

If you have never synced carbs its also worth doing in my opinion especially anytime you take them off. Here is another Dangar video.

https://youtu.be/bsHCMJnRY9A



I would start with those three things first, if that doesn't solve your issue, there is regular maintenance that is to be performed on valve clearance adjustments. Here is a video on a BF40 from Stu @ Dangar Marine who is sponsored by this site. Stu has saved me hundreds of dollars. Valve clearance might not be for everyone, but if you have the skill and tools it is worth doing especially on a 10+year old motor.

https://youtu.be/aVBWNAhs3XU

Most likely your sucking air or have spark issue in my opinion. Let us know how it goes and good luck.

The above recommendations by Eneusiis are all fine and should help performance.

But to answer your question directly, the following is a post I just made on another thread...

Well, I think there are several de-carboning mixtures out there. I used Sea Foam for years on all kinds of engines and carbs. But for my outboard, I've switch to Yamalube ring free based on previous discussions on this forum and especially insights offered by Hondadude and JGMO. If I recall correctly, the maintenance ratio is 1 ounce per 10 gallons of fuel. The published de-carbing mixture is 2 ounces per 10 gallons. However, I double the de-carbing to 4 ounces per 10 gallons mixed in a small 6 gallon auxiliary tank. Warm up the engine, switch to aux tank, run about a gallon through it, shut down the engine for about an hour. Re-start and warm up on regular fuel, then repeat.

With your 50 you probably only need to run a 1/2 gallon or so through the engine each time.

RLI01 said:

Hi All

My Honda 50 outboard started running just a little rough - not by much but when it usually runs smooth as silk I noticed it right away.

I have new gas filter and run a gas/water filter too. Regular oil change also.

I live in SC low country and have seen the commercial oystermen run Yamalube Combustion Chamber Cleaner thru their outboards.


Is this something I should do?

Anything else I can do? I don't want to damage/screw it up - I know how easy it is to do something like that

Honda dude are you out there - you sir have been very good to me in the past with your wisdom

thanks y'all
Simon - RLI01

Click to expand...

Sorry, missed replying to the comment about additives. I run a small mixture in all my tanks of the following: Yamalube, Seafoam and Marine Stabil.

The additives might do the trick.

Everything said above could contribute to poor idling.

The most common that I see, is simply a blocked idle passage.

Run the engine on a hose and pull each plug wire off one at a time and see if the engine quits or if the rpms reduce. If you pull a wire and there is no reduction in rpm, hold the plug wire close over the spark plug and listen for the ticking of the spark. That is not an absolute proof that you have spark, but works most of the time.

If you have spark but no reduction in rpms, then you have located the problem cylinder. Then the problem could be fuel related (carb problem/blockage) or internal cylinder issue (which you can eliminate with a compression test)

If you get it narrowed down to the carburetor and you remove it and disassemble, be very observant of the float setting. There is an actual measurement for the float height (I do not have it handy), however, if the float is parallel with the base of the carburetor, when you hold it upside down, you are close. If you see that it is not parallel, check the float valve (needle). It is a two piece part. The is a very small black plastic insert at the top of the valve. Sometimes they swell up from the fuel and causes the float height to be too high, limiting the fuel flow.

One other item that could cause the problem is a bad spark plug. Only use NGK DR7EA. No substitutes. If you do not have any new ones available, just switch it with another cylinder and do the drop test described above and see if the problem follows the spark plug.

Make sure you oil level is about 1/4 inch below full, so your plugs do not foul.

If you get so far as to balance the carbs, do not follow the Dangar Youtube video. He makes interesting videos and, in general, what he is doing is correct, however, with that vintage of carb set up with the bystarter (the white round device on the top carburetor), when balancing the carbs, you need to clamp off the vertical hoses going between the carburetors in order to properly isolate each carb/cylinder combo. Unless one of the carbs is way out of sync, those tubes will make it look like the carbs are properly sync'd.

Your 2005 should have the same bystarter arrangement.

There are other things like thermostat stuck open, but I would start with the basics and try to narrow down the source by elimination of things that are working properly.

Mike

Thank you everyone - hondadude.

I have isolated the prob to the top cylinder not getting fuel.

I did compression test too all even at +- 125 the offending spark plug sooty and oily -
All cylinders/plugs sparking.


A few questions - Carbs - can they clean in singles - should I do all x3 carbs while Im at it

Im going to need a manual - whats the best one to get/download


Again thank you all

Simon

It might be possible to remove just the top carburetor, but there are several hoses that interconnect on the rear of the carburetor bank.
I would recommend that you remove the entire carburetor bank with the intake manifold. If you only want to clean one carburetor after that, it is up to you.

It will be so much easier putting the hoses back on that way.

Before you pull them off, check the bystarter. It is the round white porcelain part that has a wire going to it. It is held on with one phillips head screw.

Remove it and you will see that it is a needle. When the engine is cold, that needle is retracted, allowing additional fuel to enter the combustion chambers.

As the motor warms up, the voltage going to the bystarter causes the wax inside to expand and push the needle out, closing off the valve and cutting off the extra fuel flow. The engine then slows down to the standard idle.

It is possible that the needle is not closing off the valve and you are flooding the top cylinder, causing it not to fire.

You can test the bystarter, once it is removed, by measuring the length of the needle from the base of the porcelain, then applying 12v to the pins on the connector. Let is sit for about 5 minutes, then remeasure the needle the same way. That length should have increased. Normally, the increase is about 1/4 inch or so. If it does not increase, then you have a bad bystarter and have probably found your problem.

As for a manual. The Honda Marine Carburetor Manual TM044, 4th edition is what you are looking for. I have just tried to find a link to it, but I can not find one on the Honda Amazon, ebay, or Honda Manual sites.

The 4th edition has the information to explain the bystarter arrangement.
If you decide to disassemble the carbs before you get a manual, take good pictures of the hose layout and connections before you take it apart. Take the pictures, even if you have a manual. It will make reassembly much easier.

Mike

Just a comment on your compression readings, they should be around 180PSI, did you do them with the throttle open full, if so your engine is not in a good state.

Thanks y'all - Mike

I drained the carbs - a little junk not much - tested the bystarter and it was working- With all the fiddling I guess it cleared itself - that said I will be soon removing the 3 x carbs and cleaning I will also be much more careful with a stabil type additive and draining the carbs after use

I did purchase the $30 online repair manual from Selor It appears to be very detailed and a good resource

Regarding the compression readings - no throttle not wide open - actually my compression tool was to large for the spark hole - the local marina mechanic let me bring the boat by on a Sat morning and we tested it quick - they where all the same and I did not even see the dial had to get it done quick - Ill check again properly thanks

Thanks again - Simon

Thanks to everyone who helped - I rebuilt and cleaned the carbs and we're back to running great again - Ive also started to disconnect the gas line and run out the gas as well as draining the carb bowls after use

thx hondadude

best Simon