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Honda B100 won't idle

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seedman76

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I'm the original owner of a 1984 (I think that's correct) B100L. The actual number on the identification plate is B100L-1600917. From my research I believe this is a 1984. Manual pull start. Little use overall and is in outstanding condition. It's been sitting for several years without use. Carb was not drained completely. I'm trying to get it running again and having issues. It started up on 4th pull but won't idle and won't start unless fully choked. It'll run in neutral with me feathering the throttle but as soon as I let it idle down it dies. Of course if I try to shift it into gear it dies b/c I have to idle it down before shifting it. I'll put it in gear but before I can rev it up it dies. Initially I had fuel spitting out of a port on top of the carb (see pic with yellow circle around port). No expert in this area but knew enough to know that wasn't normal. So I removed the carb and used carb cleaner to clean as much of the carb as I knew how. This is only the third carb I've cleaned so I really didn't know how far to take it apart. I cleaned every port I could see but didn't remove any needles, screws, etc. I was afraid I'd screw it up worse. I put it back on the motor and that solved my problem with fuel spilling out the top port. But it still won't idle and only starts at full choke. Any help on how to solve my issue would be greatly appreciated. It's hard working on this stuff when I'm a newbie but I do enjoy learning about it and there's no other way to learn than to just dig in. Thanks again.
 

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Hi,

MAN! That baby looks almost brand, spankin' NEW!
BEAUTIFUL!

First off, it doesn't sound too serious and, if you do end needing to take everything out to clean, I don't think you will hurt anything.

About the worst that could happen is if you lose something. Because, many parts are no longer available.

Although, you would need to be cautious about seating the mixture screw too tightly or stripping a screw thread. Other than that, not much to worry about.

Let's try something simple and easy and see what happens.

In your photo, just outside of the yellow circle you drew, bottom left, is a screw head. That is the cover screw for the carburetor's slow jet. See item 10 in the link below:


That screw is no longer available so don't lose it.

Remove that screw and spray a LIBERAL amount of carb cleaner in that jet hole. Re-install the screw.

Remove both spark plugs and pull the engine over a couple of times.

Smear a SMALL amount of dielectric (tune-up) grease inside each plug boot and Re-install plugs and wires.

See if it will start and idle OR if there seems to be some improvement in the symptoms.

My point is, if you can get it to a point that it will run well enough to put a decarbonize level dose of Sea Foam or other quality cleaner through it, you may get it cleared up without taking it apart.

One thing to keep in mind also, about an engine that's been stored a long time, is the possibility of critter nests in the crankcase breather system. See items 2, 3, 22 and 23 in the link below:


This engine will not idle well and will stall if the breather or hoses are plugged with "stuff".

Good luck and let us know what happens.
 
jgmo said:
Hi,

MAN! That baby looks almost brand, spankin' NEW!
BEAUTIFUL!

First off, it doesn't sound too serious and, if you do end needing to take everything out to clean, I don't think you will hurt anything.

About the worst that could happen is if you lose something. Because, many parts are no longer available.

Although, you would need to be cautious about seating the mixture screw too tightly or stripping a screw thread. Other than that, not much to worry about.

Let's try something simple and easy and see what happens.

In your photo, just outside of the yellow circle you drew, bottom left, is a screw head. That is the cover screw for the carburetor's slow jet. See item 10 in the link below:


That screw is no longer available so don't lose it.

Remove that screw and spray a LIBERAL amount of carb cleaner in that jet hole. Re-install the screw.

Remove both spark plugs and pull the engine over a couple of times.

Smear a SMALL amount of dielectric (tune-up) grease inside each plug boot and Re-install plugs and wires.

See if it will start and idle OR if there seems to be some improvement in the symptoms.

My point is, if you can get it to a point that it will run well enough to put a decarbonize level dose of Sea Foam or other quality cleaner through it, you may get it cleared up without taking it apart.

One thing to keep in mind also, about an engine that's been stored a long time, is the possibility of critter nests in the crankcase breather system. See items 2, 3, 22 and 23 in the link below:


This engine will not idle well and will stall if the breather or hoses are plugged with "stuff".

Good luck and let us know what happens.
Click to expand...

JGMO, I'll try those things this afternoon and post a reply. When I cleaned the carb yesterday I did remove the slow jet screw and liberally sprayed carb cleaner down there. I may have a couple new spark plugs and will just replace them if I do. Is there a good way to check for critter nests in 2, 3, 22, 23? I'll heed your advice and reply here asap. Glad you liked the motor. I need to post a couple more pics b/c it's in "like-new" condition. My dad purchased it new around 1990 but it was a 1984 motor. Somehow the dealer had gotten 7 of these motors from Honda and was selling them at a nice discount. All were brand spanking new. My dad didn't hesitate to buy one. It's always been used as a kicker motor on our 18ft boat. Other then a couple trips to Canada where it saw quite a bit of use it just hasn't been used much (hardly at all in the last 15+ yrs) hence how it's in such pristine condition. We love this motor...just got to get her revived and running top notch. Thank you.
Click to expand...
 
Yes, I would love to see a couple of pictures.

I don't think that I would disturb that breather unless absolutely necessary. Those parts and hoses aren't available and would just add to your current headache if you broke something checking them out.
I was just letting you know of the possibility.

Now that you say you've already sprayed the slow jet, I think that you will probably be needing to disassemble the carb and do the "Full Monty" cleaning.

But, first, you might try pulling the slow jet plug again AND remove the mixture screw. Item.6 in the first link I sent.

Count the turns as you back it out. Spray into that hole and then into the slow jet hole. Do that several times, alternating between holes each time.

Then replace the screws using the same amount of turns for the mixture screw.

Then try running again and see how that goes.

If it acts the same, I would pull the carb and clean.

You should pay particular attention to the Inlet valve and seat since you said that gas was coming from the carburetor vent hole. That indicates that the float was possibly sticking so there may be a buildup of shellac from the old fuel left in...and on... there.

Shake the float when you have it off and listen for fluid inside. If so, that would be bad because those are unavailable. But it's a rarity so hopefully it's ok.

Remove the main jet and emulsion tube making a note as to which end is up because some will fit either way.

Inspect all the holes in the emulsion tube and main jet for shellac buildup. You shouldn't need to do anything more than spray and maybe poke small pieces of cloth or thread into the holes to clean them. I don't recommend using jet files or anything hard as you could accidentally enlarge them.

Spray up into the main passage while the emulsion tube is out and open the throttle and watch for fluid to exit the orifices in the rear top of the carb throat. Hold your finger over the main/high speed air jet passage [see below) while doing this.


Looking at the front mount flange you will see two passages. One on the flange itself and the other slightly inside the carb throat.
Those are the air jets for low and high speed. Hose them out thoroughly with carb spray.

The recessed passage is for the slow air jet and the one on the flange is main/high speed air jet.


Pull the idle mixture screw, keeping count of the turns,. and spray in there while holding your finger over the low air jet passage. Watch for fluid to exit the one idle orifice at the top rear.of the carb throat.

Use the carb cleaner spray straw end to individually cover each delivery orifice at the top rear of the carb throat, including the single idle one.

Give each one at least one good blast. You may need to devise a way to prop the throttle wide open to do them all except for the idle which can be seen/accessed with the throttle closed.

Any questions, ask away.

Good luck.
 
Only question I have at this point is what is the emulsion tube? Is it part of the diagram, in the link you sent? I ordered 2 new spark plugs which will be in today and I'll install them and give it a try. If it still won't idle, I'll start on your instructions from the top and work my way down. It might not be spark plugs but worth a shot as it's an easy (& cheap) fix if it did indeed solve the problem. Thanks very much!!! I'll follow up again asap.
 
Hi,
Yes, sorry, it's #12 in the first diagram I sent. They changed terms from emulsion tube to main nozzle and I didn't catch that.

I was having you remove the plug to "safety clear" the cylinders to prevent liquid slugging after all the spraying of cleaner. If liquid cleaner gets in and pools up in the manifold, it could hydro-lock the engine. So don't neglect to pull it over a few times with the plugs removed after trying to clean the carb while it's still bolted on.
 
JGMO, first of all, thank you for all your help!!! Update after working on it tonight. I put 2 new spark plugs in with dielectric grease. Even though I'd taken the carb apart once I still went ahead and removed the slow idle screw (while carb was mounted back on) and sprayed more carb cleaner in there. I then tried starting it as you suggested. Initially I thought I was in business. It ran better for about 1 minute and even idled on it's own briefly (w/o me feathering the throttle). But it quickly died and wouldn't idle any more. It was just running like before...won't start unless I pull the choke out. Then fires up first pull, push choke back in and it purrs like a kitten as long as I feather the throttle. It just won't idle and therefore I can't shift it into gear (F or R) as it'll die before I can make the shift and get back on the throttle. It also seems to lag power just slightly (not getting enough fuel?) when I rev it up as much as I can while in neutral. But it was running good enough that I was able to spray about 1/3 a bottle of Sea Foam in the carb while it was running. I did this in short bursts over a 10-15 min period. Again I removed the slow idle screw as well as the slow jet plug (item 6) making note of how many turns it took to remove it so I could get it back in the same place. I sprayed a liberal amount of card cleaner in both those places. I then started it up and ran some more Sea Foam into it. It still runs the same as when I first started it up. Won't idle and seems to cut out a little when I rev it up in neutral. My next move is to remove the carb again and do a full cleaning just as you suggested I try if none of this other stuff works. At least the carb is easy to take off and I'm enjoying the process. :) I ran out of time tonight and it'll be next week before I can work on it again so I just wanted to give a quick update and will follow up next week after a good carb cleaning. Thanks again for your generous help!!!:)
 
Well, thank you for the progress report ....and that's what I think that you are making....progress.

I am also encouraged by your enthusiasm. It does help to have that when working through a problem like this.

Standing by and securing the cheering section bleachers ;) until you update next week.
 
It often takes 3 or 4 tries to get these simple carburetors clean.----Running fuel out after use keeps carburetors clean during storage.
 
Do you also have a high concentration of sea foam in the fuel tank? Gets to more places than spraying it it the throat if that’s what you are doing.
 
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