Logo
FULL SITE MENU

2002 50a carb change choke to se system

C

Chubbsdad

Member
Hi all I have a couple of queries
can anybody point me in the right direction here.
I am in the process of rebuilding a used 50a. When I bought the unit from ebay it came with an old set of unusable choked carburators. I have since managed to get a set of good SE type units but I am unsure if I have to make any modifications to the wiring . I understand that the SE type units are powered all the time and the choke was switched to operate , do I just plug the SE lead into the same connector as the choke,or is there a modification I have to do.?
next up
I have my engine running on test in a water bath , but my idle seems to be a bit rough , I have reasonable compression on all units 195 ish hot at Wot, I have done a few syncros and have an
idle of around 1000 +_ 50 but it seems to stutter a bit , if I pull the plugs I have the following
pull no 1 stalls the motor
pull no 2 not much change in rpm
pull no 3 definite change in the rpm
from that it would seem that no 2 is not doing very much at idle ,I have had the carbs off and cleaned and all seems to be ok inside . It responds reasonably well to throttle but since I am running in a bath I cannot put it under load. Do you think that I still have a carb issue (no2) or is it possibily an electrical one ?
I have checked all the sparks and they all seem to be good at cranking speed , the mixture screws are all set at around 1 turn , now on investigating the carb issue I found out that the emulsion tubes are different for the SE units would that matter to the running of the engine or does it get the same gas as the older choked carb models
FYI I am able to run the engine by shorting the terminals on the 14 pin connector and the thermal choke has a seperate 12 volt feed
Thanks in advance
 
A few issues here.....

First...The idle mixture screw turns will vary by carburetor number. What are the numbers on your se valve carbs? The turns will be more than 1.

Second...the se valve does need to be on all the time that the motor is running. You can not just hook it up to the choke leads. In the se valve 50's, the power to the se valve comes from the CDI unit. The older 50's do not have the connections to the CDI for the se valve. The current draw is about .5 amps, so you have to choose wisely where you will get the power.

Third....you will not be able to properly balance your carburetors until the se valve is fully closed (extended). You also have to clamp off the vertical hoses that go between carb 1 and 2 ,carb 2 and 3 (part #24) http://www.boats.net/parts/search/Honda/Outboard Engine/2005/BF50A5 LRTA/CARBURETOR/parts.html , as well the hose going over the top of the #1 carb ...#29 http://www.boats.net/parts/search/Honda/Outboard Engine/2005/BF50A5 LRTA/CARBURETOR ASSY/parts.html.

You will probably have to raise the idle some to keep the motor running during this procedure. Once you get them balanced, remove the clamps and reset the idle.

It sounds like #2 carb may still have a problem, but I would not jump to that conclusion until you try balancing again. It may just be the se valve (open) that is causing it too run too rich.

Post the carb numbers and then we will know what the number of turns should be.

You might be able to power the se valve off of the key switch. That is certainly not the standard way to activate it. You want to be sure that however you do it, that when the motor stops, the se valve no longer has power.

Mike
 
Hi Guys thanks for the replies��
My Carb numbers are 31E(B)VD 12 nos 1and 2 Vd11 for number 3,
I just assumed that the introduction of the SE Carb was in line with the start of the emmision control therefore I set it to 1 turn. Mike I take the point about tapping my SE feed from somewhere heavy enough I will take it from the old Choke feed via the key start.
I have the honda carb manual but it is a 2007 revision so its slightly after my year. But what a great little book .
cheers
andy
 
The SE valves operate just the opposite of the choke on the key switch. So...I'm not sure JUST using the choke switch would work for you.

The old choke would activate from the key switch because you applied power with the switch and the choke would open when you released the switch and CUT the power.

However, the SE valve is ON when there is NO power and turns OFF when power is applied.

The SE valve is nothing more than a little electric heater really. When the engine is cold the enrichment circuit is open. The engine then receives full enrichment and starts. As the engine runs and is CHARGING...power is constantly being fed to the SE and it begins heating up. As it heats up...expansion takes place and the valve's needle moves to close the enrichment circuit and lean out the mixture for normal operation. This takes place over a 1 to 2.5 minute time frame depending on ambient temperature. While the engine continues to run, power is constantly supplied to the SE valve to keep the enrichment circuit closed.

I think you could rig a LATCHING RELAY to the supply side of your key switch choke feed and accomplish what you want to do. Since there is power going to the choke switch when the ignition is in the run position...you can wire that to the latching circuit of the relay. You could then use the choke switch to activate the relay with it's momentary function. The relay would apply power to the SE valve with just a bump of the choke switch and then KEEP power going to the valve while the key is in the RUN position. Power would then be cut to the valve when the ignition switch is shut off.

You would just need to REMEMBER to bump the choke switch AFTER the engine starts. Otherwise, the SE valve will remain open and the engine would be rich at all times.

You could also wire in a "reminder" led lamp in parallel to the latching feed to the SE and train yourself that when the (pick a color...except red or green) blue light is on.....the mix is "normal". HEY! more lights...more fun....RIGHT?

At least that's ONE way to go.
 
Wow ! 2.1/8 turns is a long way from 1 turn so I guess it should run a tad more stable . Thanks Mike where did you get the info? Or is it just experience !!!. . I had the idea of a latching relay in my mind and as I am running a 2006 30d at the moment I hope I will be able to link it to the "start run" feed . The remotes dont have a choke button but I believe the old wiring is still in place .
thanks for all your help ,this is a great forum, happy boating .
Just a change of subject .
Anybody ever built a test tank for load running, my nearest water is around 30 mls away and to test the 50 I need to to attach it to my boat ,which is a bit tricky as its got the 30 unit on it. The 50 is a bit of an unknown and I really dont want to go drilling holes in my transom if its not going to be ok . It would be nice if I could use a Dyno for test but as far as I know there not available here in Scotland so it look like im in for a bit of diy testing any ideas ??

Andy
 
The info is in the Honda Specification Book. http://www.amazon.com/Honda-Marine-...49032418&sr=1-23&refinements=p_4:Honda+Marine

It is probably in the most current Service Manual....but I knew it was in the spec book. It has the settings for all of the Honda Outboards.

When it comes to a test tank....here is something to consider. http://www.tractorsupply.com/tsc/pr...4-ft-l-x-2-ft-h-100-gal-capacity?cm_vc=-10005

I doubt that there is a Tractor Supply store in Scotland, but I am sure there are similar products used there. This one is only two feet deep, so you may need to find something a little deeper.....and make some sort of cover to minimize loss of water when you power the motor up.

American Honda just today announced the introduction of a relay that is used to slave power NMEA2000 networks. It supplies fused power directly from the 12v battery to power NMEA 2000 network when the keyswitch is turned to on. It costs about $29 US. It has color coded connections that go to the key switch. That should work your se valve. I am not sure if it is available in Scotland....the part number is 06332-ZZ3-000AH. It looks like a small trim relay, that is used on most outboards.

If that is not available, you could use any low current relay wired into the key switch "on" circuit. You just have to wire it up yourself. I sounds like you are pretty creative, so you may come up with something even better.

Let us know how it all works out.

Mike
 
Thanks Mike for your invaluable help . I had no idea such a book existed perhaps I might just invest in it . Things on your side of the pond always seem to alot easier and cheaper to find than overhere (guess thats due to the bigger market) I will check out the new power supply relay with my local shop . You would think that the oval tank would be easy to obtain , but oh no !! Not here in UK !!,,From a quick look on net I think it really fits the bill (after my design investigations) Not to worry I will keep heading forward as I would like to get my unit ready for spring . I will let you know in a couple of days If I overcome the idle problem
happy boating

Andy
 
Cheers Chawk .
I have found some items under " tin bath" I did checkout the local farm suppliers but they all seem to be a little expensive ,and not quite the right shape !!
 
Ok finally got some time to reset my carbs 2.1/8 turns I also purchased a start switch and wired in the SE carb on the old choke cables via the start unit
Started it up in the test tub and away she went , checked the idle but it was way too high so I wound down the idle but I cant get it below 1100 rpm Ok so what did I do
before start up
checked all Idle and transition ports on all 3 carbs clear.
checked operation of SE unit and verified good needle condition
reset mixture screws to 2.1/8 turns
rebuilt manifold unit with new gaskets.
after start
Adjusted stop to minimium
pinched SE pipes to see if it was leaking little or no change
removed plugs
no 1 reduced rpm no stall this time
no 2 little or no reduction
no3. Reduced rpm
seems like I still have a problem any ideas on whats going on
cheers Andy
 
When you cold start it, does the rpm go higher than 1100 then drop down to 1100? If it stays at the same rpm, your se valve may not be getting constant voltage or may not be closing down.

Also, check the throttle stop to be sure that it did not get bent, thus preventing you from adjusting the idle all the way down.

And, of course, may sure all of your gaskets are properly in place.

Mike
 
I'm with Mike. First check SE that valve is getting power and that needle extends a minuteute or so. If that checks good then it sounds as if you may have "uncontrolled air".....a vacuum leak......causing the high rpm.. You can use carb spray or propane to find any leaks.

Besides the bent linkage Mike speaks of, you need to find ANYTHING that might not be allowing the throttle plates to fully close if that is indeed what is happening.

The rule of thumb is that, on a properly jetted carb, unwanted air will increase idle. But...more fuel...more rpm...so if your jets are too large, that could make getting the idle down difficult too.

What did the weak cylinder's plug look like? Lean? Rich? That could be a clue.
 
Last edited:
Hi Mike
it seemed to stay at the same rpm indicating that it was my SE valve , however I clamped all three pipes closed at the same time and it made little or no difference.( no rpm drop) .
Logic would say that this is the problem so I took it out and tested it via a12 volt supply and it works ok IE extends when hot and like I said the needle seems fine.
Unfortunately due to our time difference it is now 20.00hrs and around 3 celcius outside so I have given up for the day. Now I wish I had a heated garage.!!!!!
I didnt strip the carbs only jetted and blew out the Idle etc as described above . I replaced the carb insulator gaskets and the manifold gasket . Seems like I will have to remove the air silencer and try attaching a tube to the SE fuel line and see if it closes under voltage. If that is ok , Well???????
cheers
Andy
 
Jgmo
Hi our posts crossed so I didnt read yours until a few minutes ago. My gaskets should be good but I will check tomorrow with some " go go juice" in an around the joints. I will also check my wiring for the SE unit it was warm when it was running but just to be on the safe side I will recheck that it has a permanent supply .
I made some enquiries about the latching relay that Mike suggested but it does not show on the Honda system overhere yet . I will have to make something when I sort this out ,however at the moment its wired into an auto switch.2 toggle switches for on and off and a push button to start. This seems to be ok,but there are lots of color codes on the harness so I will just have to recheck My understanding is that I should be able to take a feed from the
"White and black" and connect to the original choke "Brown" connection and it should be fed with 12 volts
I will let you know tomorrow.
Andy
 
Hi again . Finally managed to check out the carbs ,sprayed some juice around the manifold joints but no change in Rpm . I stripped the manifold off and removed the air silencer and set a piece of tubing into the SE air inlet passage, powered it up using a seperate 12 volt battery ,kept puffing thro the tube and eventually it closed down . I then replaced the manifold with the Mounted SE tube back on the engine and started it (after it had cooled down)started it up and away it went. It ran faster for a couple of minutes then slowed as the SE unit operated ,I verified that valve was closed by trying to puff thro the tube . The slowest RPM I can get is around 1100 . I guess I have a carb problem but Im not sure which bit.
The problem I am finding is that the more you play with these things the worse it becomes. Unfortunately spares on this side of the pond are quite expensive and if you import them from the US they can slap you with 25 %duty.I am thinking my best route forward would be to replace all the O rings ,as It must be the emulsion tubes that are leaking at that Rpm . I have checked the mixture needles and the tubes but they seem to be ok ,no scratches etc. I would appreciate any input that is going . One of my problems is these units are used so I dont know their history . Mike could you let me know what year these models were introduced ,that would give me some possible indication of use.
Andy
 
Before you pull too many things apart, take the throttle linkage off that connects the three carburetors. It will through the carbs out of sync, but should allow all of them to close completely. See what happens.

The SE valve 50 was introduced in the US in 2005. Bf50A5 models.

Mike
 
Cheers for the information about the date, gives me a starting point Mike ,will remove the throttle link tomorrow to see whats happening . I guess if it reduces speed then it shows that there is some kind of misalignent but I would think they have to be a tad open to run at all?
 
Hi all. The saga continues. This morning I started up the engine, let it warm up and then removed the throttle link from the carbs as "Mike" suggested . The rpm dropped from about 1100 to approx 700 ,but did not stall. I then made sure that all the plates were fully closed still no shut down ! Next I began clamping off the SE tubes to see it that made a difference . The top and no 2 tubes no difference but I did notice a slight change in the idle ,a little smoother!!
I clamped no 3 tube and finally the engine stopped. Success I thought I have an air leak at no 3 SE tube .
I replaced the tube with some new pipe and did the same again , hoping that the engine would stall when I removed the throttle link but no , not until I clamped no 3 again did it stop..
My thoughts are now back to the SE unit . In the Honda carb manual it says when the valve is closed a " gentle puff of air should not pass" I can verify this on the running machine , but what is a Gentle Puff !!!!! .
I also replaced the no 2 SE tube but it made no difference .
So my investigations lead me to believe I have an air leak in or around no2 carb . I have checked the throttle and the roller is sitting on the cam but is not touching the opener so I believe it is closed. I will continue with my investigations but any ideas suggestions would be more than welcome .
Andy
 
Just been rereading my Carb manual . Honda says the "SE system is a complete starting system on its own "
stating that the " Throttle Valve must be completely closed " for it to work correctly , can anybody confirm .
That being the case I assume that there is still a small % of air passing from the SE valve allowing for good atomisation at idle and therefore the leakage I am trying to find does not exist!!!!!!. Ok so what does that mean !!!
If the best Rpm I can get is 1050 when synchronised, does that mean that my engine needs to be overhauled as I am opening up the throttles on number 2 & 3 carbs to compensate ?
Andy
 
Last edited:
A very GOOD engine mechanic once told me that the one of the BEST tests to see if you are working with a SOUND engine is if it starts easily and idles smoothly. It sounds as if yours does. I mean...if it will idle at 700....I doubt it needs overhauling.

As far as the throttle plates needing to be completely closed.....if that's the case, WHY then did they provide a screw to open them with to set a higher idle when needed?? I think they are just pointing out that you shouldn't hold the throttle open upon COLD start so the SE can "do it's thing".

I think your idea about the orings is probably much closer to the mark. If you have been taking the jet sets out....or even if you haven't.....and not used new seals up there.....that COULD be a problem. That seal (tiny oring) is very critical. Although...when it is leaking it usually causes poor starting and low performance....not high idle. But I don't think I would EVER want to open one of these carbs up without having new seals handy.

Not knowing who or WHAT has been farting around with those carbs could also be part of the problem. If someone has put in over sized orifices or, worse, been over sizing by accident by putting drills and the like to them....who knows?

Did you try "juicing" around the throttle plate shafts? That's another place that will develop unmetered air if too badly worn.

Just throwing out ideas to see if anything might stick.
 
Thanks jgmo
Like your good mechanic I too believe that I have a basically sound unit. I did have the carbs apart but not down to the bare bones , so I guess it is time to replace all the O Rings . This morning before reading your post I ordered the carb kits.
The problem with Marine Spares is they seem to get an "instant Mark Up " even though they could be standard items.
Regarding the SE design, to me it makes sence to allow a fixed air ratio when dealing with emmision control on the carburator ,the fact that you can fine tune the throttle units would in my mind make up for any wear in the mixture screws without drastically effecting the emmisions?
Over the years I have found outboards and boats, infact ,anything Marine just end up as a Bottomless Pits that I seem to throw money into. Now that I am retired its not so easy to justify new this!and change that!.

Having been active on this forum for the past couple of months ,has given me a great pastime and lots of invaluable help . I have been involved in marine engineering for over 50 years and as time goes by, the decisions that were once Black and White,now seem to take on a slight grayish effect. Its good to know that I can turn to the forum and find a great array of knowledge and ideas to confirm my thoughts.
My next step will be to build the test tank before spring so I will keep you posted.
Many thanks ,merry xmas to all those who read and contribute to this forum
Andy
 
Just going back to basics before you take everything apart.....

When you balanced the carburetors....did you use #3 carburetor as the reference? If not, and you used #1, you may have the sync screws all out of wack.

What would happen if you backed the screws off until all the carburetor plates are closed or near closed when the linkage is reconnected? Then rebalance....using #3 as the reference.

Just a thought

Mike
 
Cheers Mike .
I did sync the carbs using no 3 as reference ( the lower unit) but its an interesting idea so I will give it a bash. I will post my findings ,however it may be in a couple of days before I can get round to it
Andy
 
I think going into those carbs and VERIFYING proper jets, passage cleanliness and good, fresh seals gives you an excellent starting point for getting idle and sync where you need/want them.

AND.....

MERRY CHRISTMAS RIGHT BACK ATCHYA!!
 
Hi Mike . Just thought id update you .
Backed off all the throttle screws on the carbs and removed the throttle linkage , the engine still,ran around 700 rpm but again as soon as I clamped no 3 SE pipe it stalled . I then replaced the throttle linkage and synched them using number 3 as the reference . Unfortunately by this time all 3 carbs had fuel overflow ,I guess from sticking floats or other areas from my messing around. I still was unable to set idle at 950-1000 so its a definate strip down and change O Rings plus, 10 mins or so in my ultra sonic bath to try and remove any small particles that seem to be giving me problems. I have had the carbs overflowing before but a bit of throttle seemed to stop it. But now im sure there is still some debris in the system . Probably been my problem all along. My fuel and filter are new so it must be in the carbs .
 
Chubbsdad said:
Hi Mike . Just thought id update you .
Backed off all the throttle screws on the carbs and removed the throttle linkage , the engine still,ran around 700 rpm but again as soon as I clamped no 3 SE pipe it stalled . I then replaced the throttle linkage and synched them using number 3 as the reference . Unfortunately by this time all 3 carbs had fuel overflow ,I guess from sticking floats or other areas from my messing around. I still was unable to set idle at 950-1000 so its a definate strip down and change O Rings plus, 10 mins or so in my ultra sonic bath to try and remove any small particles that seem to be giving me problems. I have had the carbs overflowing before but a bit of throttle seemed to stop it. But now im sure there is still some debris in the system . Probably been my problem all along. My fuel and filter are new so it must be in the carbs .
Click to expand...

Chubsdad:
 
Interesting problem. I spent some time trying to get my BF50 to cold start . Mike (HondaDude recommended I purchase the Honda carb manual. I would encourage you to do the same. I found that I needed move throttle to aprox 50% to get reliable starts. Cleaning all 3 carbs was required to start
 
Back
Top