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Any help troubleshooting this would be appreciated.
I have a 2001 Honda 50. At the end of the last season it started to run rough. This spring I did all the normal maintenance such as changing the spark plugs, oil (in the fall), and changing the lower gear oil. I was hoping that the problem went away, no luck however. I bought a carb sync gauge/tool off of ebay. I had it hooked up today and the needles were bouncing around quite a bit. I got the carbs synced the best I could (using the repair manual for a guide) and the motor was still running rough. It seems to be running the roughest in idle and to a lesser amount when I increase the RPMs to around 2500. I then pulled the plugs one by one and the engine ran equally as rough with each plug wire pulled.

Any ideas on what might be causing this issue?

Hello,
Here is the deal, FUEL, FIRE, COMPRESSION. Each of these needs to be at the correct time in the correct amount. Once fire is eliminated as a cause move on to fuel. Most problems are one of the first two. Compression gets into mechanical issues. I know this sounds basic but it is not rocket science. Just logically check the systems and don't assume anything. Make sure that each plug is firing consistently and the timing is correct. If you can run the motor at misfire. Operate the choke for each carb separately. If you slightly richen the mixture and it runs better then clean and service the carbs. If it is running rich the plugs will turn black. If it's fuel injected then you will have to get more inventive to check mixture but injectors plug up just like jets do.

good luck

I would be willing to bet you have some clogged passages in your carbs. I recently went through the same thing on my bf50a and found numerous of accounts of people online having the same problem. Seemed to be the main gripe abot the motor. Just google bf50a and carb. I even read a couple acounts of shops charging people for new carbs since the shop didn't know how to clean them out completly. Syncing them is good, but they should not have became unsynced on their own. More likely I would guess some gas started to varnish and clog up the carbs.

You can try a shortcut like seafoam but most likely to get them 100% you will have to take them off and clean them manually. If you are fairly mechanicial its really not too bad. If you figured out the sync process its no more difficult. The largest culprit I found are the small holes in the carb body itself since they are so tiny they easily varnish/clog with fuel as it ages. I think some people overlook these. As you look at the throttle plate there are about 5 tiny holes in the carb body. Pop out the idle tube, clean it, and check it carefully, there are a few small ports on it too. Then with it out it use a nozzle on a can of carb or brake cleaner to spray directly into the port where the idle tube seats. You should then see the cleaner spraying out of all the tiny ports in the bottom of the carb body with nice presurized streams. If not they need furthur cleaning. I was able to use a single strand of copper wire after unbraiding it from a speaker wire to manually clean the tiny ports. Be very careful on them, I was told by a honda tech damage them and its game over. Direct blasting of carb cleaner was not enough for mine. If you are careful you may be able to salvage your gaskets, but its recommend to replace them and get an oring kit. The oring on the idle tube is very small and fragile so you may have to replace it. If you decide to give it a try and run into any problems let me know. Good luck!

Thanks for that Seapup. I was thinking that the carb was the issue too, but I just did not want to deal with it. For about $800 that the shop wants I will be taking this on myself.

Do you or anyone else have a list of parts (so that I can order them) that I should plan on replacing (gaskets, o-rings, etc) when I am doing this? That would make the entire process go a little easier.

I will review the process in the shop manual and see if I have any other questions. Once again thanks for the help.

Before you go and tear things apart run two tanks full of Seafoam and see if that cleans your carbs. Also once you do tear them apart you can count on around $300 worth of parts because you got to buy each carb part seperate excect the gaskets which you can get in a kit.

I agree on the Seafoam being a good choice. Is there any chance of something simpler like water in the carb or a blocked fuel filter?

I tried the Seafoam route last fall. I ran what I though was a fairly concentrated partial tank of gas through. It did not really help. What concentration should I use the Seafoam at? I don't want to damage the non metal pieces in the motor.

I am going to be changing the fuel filter though, just to be sure.

If I end up taking the carbs apart, all I would need is the carb kit as I plan on cleaning all the pieces inside and reusing them. I just don't know if there is a part number for the carb kit, but I guess I will call a Honda dealer.

I think if those tiny ports get gunked bad you about have to do it manually. The chemical cleaning was not enough for my carbs, but they were extreme.

If you decide/need to tear them down -

You will have to check your serial, but this should be the 2001 50hp:

http://www.boats.net/parts/search/Honda ... parts.html

You will probably need the gaskets on both sides of the carb depending on how you take them off, 1x#38 and 3x#22 About $20.


I was recommended to get the oring kit, part # 2 but didn't need it. The one on the idle tube is very fragile so be careful not to rip it when you re insert the nozzle and keep the carb cleaner off it.

The rest of the parts are pretty much all metal so as long as you are careful they should be cleanable/reusable. They are either clgged or not. You can check the float needle for wear. The first time will probably take 2-3 hours, once you have done it it is pretty quick though.

Seapup wrote:I think if those tiny ports get gunked bad you about have to do it manually. The chemical cleaning was not enough for my carbs, but they were extreme.

If you decide/need to tear them down -

You will have to check your serial, but this should be the 2001 50hp:

http://www.boats.net/parts/search/Honda ... parts.html

You will probably need the gaskets on both sides of the carb depending on how you take them off, 1x#38 and 3x#22 About $20.


I was recommended to get the oring kit, part # 2 but didn't need it. The one on the idle tube is very fragile so be careful not to rip it when you re insert the nozzle and keep the carb cleaner off it.

The rest of the parts are pretty much all metal so as long as you are careful they should be cleanable/reusable. They are either clgged or not. You can check the float needle for wear. The first time will probably take 2-3 hours, once you have done it it is pretty quick though.

Agreed and I had to do mine manually when I first bought my boat. However sense then I just run enough Seafoam in my 2 twelve gallon tanks twice a year in concentrations to the extreme. If you don't smell it burning it's not strong enough. So basically add 1 1/2 the amount on the directions. I results are not noticeable until you fill up after running both tanks.

I got the carbs apart this weekend, not too bad of a job. However, after looking at the carbs and the parts I needed, I decided to just order the entire carb assembly from boats.net. For only $479 I will get entirely new parts and not have to worry about getting everything clean. There was also some wear to the bowls themselves. Instead of spending $200 for parts with no guarantee that I will get everything clean, I figured this was a better route. I will keep the old unit for spare parts if I ever need it.

It still beats the $900+ that the dealer wanted to rebuild them.

As a side note, don’t leave heavily treated gas/seafoam in a motor overnight….. what a mess I made in my yard. I have carbon deposits in my grass now.

tompolak wrote:...don’t leave heavily treated gas/seafoam in a motor overnight….. what a mess I made in my yard. I have carbon deposits in my grass now.

How did it get out of the motor and into the grass

It came from the exhaust in the prop. I had it in a garbage can tank, but it was spitting out too much gunk, so I switched to the ear muffs. All sorts of nasty coming out the exhaust. I did check to make sure it was carbon and not oil. It was pure black, smelled like exhaust, and did not feel like oil. I am assuming it was built up in the engine and it just got flushed out with the Seafoam.

I plan to run Seafoam in my new carbs to help clean them out occasionally. Not at such a high concentration, but just to help them try to stay clean a little longer. I think the Seafoam also broke everything loose and gummed the carbs up the rest of the way. When I got them apart there was a lot of varnish on the parts still and the jets were at least partially clogged.

I think you made a good move, as I think PO replaced all my carbs. as they looked new. If I see varnish in bowl I will replace the carbs. as I been that route a few times trying to clean them and the engines never did run the same. To many tiny holes to try to clean the varnish out.
Best to spend the extra bucks and no worries.
Todays gas I wouldn't have gas sitting in carbs more than 2-3 mo. and with a fuel additive I wouldn't do more than 5-6 mo. Varnish builds up that quick and the Ethanol decreases the octane and adds water to fuel causeing faster deteration of fuel causeing faster varnish buildup.
Seafoam only works if the fuel is slightly sluged with Varnish, if solids are there it is replacement time.
Dave

tompolak wrote:I got the carbs apart this weekend, not too bad of a job. However, after looking at the carbs and the parts I needed, I decided to just order the entire carb assembly from boats.net. For only $479 I will get entirely new parts and not have to worry about getting everything clean. There was also some wear to the bowls themselves. Instead of spending $200 for parts with no guarantee that I will get everything clean, I figured this was a better route. I will keep the old unit for spare parts if I ever need it.

It still beats the $900+ that the dealer wanted to rebuild them.

As a side note, don’t leave heavily treated gas/seafoam in a motor overnight….. what a mess I made in my yard. I have carbon deposits in my grass now.

Ditto what Dave just said.

If you will allow me slightly elaborate, Dave...

Ethanol in gasoline actually increases its octane rating (which slows its burn rate). In time, the absorption of water (sped up by the ethanol) will then cause the octane rating to drop, eventually to a level where you will have problems with just about any engine.

Preventive measures such as adding Sta-bil when the fuel is in dis-use will eliminate or delay problems like this and make the Seafoam-like cleaners largely unnecessary.

If you want to get away from these problems, just buy high-octane fuel from the pump at the outset. Not necessarily for the octane rating itself, but because it does not (at least in Canada) contain ethanol, and therefore the associated complications are eliminated.

- Brian.

God bless Art Reiders for talking me into a FIJ engine in 2002. My Bigfoot starting this spring with one bump with last falls gas in it.... .....sorry to gloat.....