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Author: Subject: Honda Carb jet question: UPDATE
Santiago
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question.gif posted on 1-15-2017 at 10:45 AM
Honda Carb jet question: UPDATE


Earlier this year I bought a used Honda 15 hp motor which I think is a 2005/2006. The reason I say 'think' is that when I enter the serial number into Honda's website it returns an invalid number. Motor runs fine other than dying when idling, especial if in gear and trolling at the slowest speed. The motor had sat for a year or two, fuel not drained, so I'm assuming the idle jet was gummed up. Every thing I can find on the google machine has a carb that does not look like mine. The first photo is the top of the carb.

A few days ago I walk into the local Honda repair center and ask to buy a new idle jet, the guy is fumbling around in the parts department for 10 minutes and comes back to the counter as says the book shows three different ones and I will have to bring the old one in to match. I show him this picture and we both agree that the idle jet is the silver slotted piece at the top left of the photo.

I put a slotted screwdriver and start to put pressure in the 'lefty-loosey' direction and it shears off. The silver head is plastic and the back of it is brass, I assume. Inside the hole is what you would expect, a round brass disc with a sheared-off stud coming out of it.

I take the small piece back to the dealer and everybody becomes super stoopid. No one knows anything and they bring a mechanic from the back and he says that is not the idle jet. He points to the round brass piece with the blue ink on it that is flush with the body and says that's it.

"How do I get it out?"....dead silence. Finally the mechanic says he has heard of people using a puller to remove them. A puller. I pick up my piece and walk out.

So before I try another shop, can someone explain to me what I have done, where the heck is the idle jet and how do you get it out to clean it? I have been advised that sometimes it's better to buy a brand new carb, bolt it on and be done with it. I'm about there.



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[Edited on 1-28-2017 by Santiago]
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rts551
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[*] posted on 1-15-2017 at 10:54 AM


what is the model number of the motor?
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Santiago
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[*] posted on 1-15-2017 at 11:23 AM


Quote: Originally posted by rts551  
what is the model number of the motor?

Well, once again that is something of a question depending on which website you are on. The sticker says: "BF15D,BFP15D". When I try to find the correct part, they make a distinction between these two models ('P' or not 'P').
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Russ
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[*] posted on 1-15-2017 at 12:07 PM


I too have a Honda 15. My local mechanic just took off the carb and took it home and cleaned it this time. Before I just took a fine copper wire and cleaned all the jets. There were 3 that I remember and was extremely careful to run the wire thru the jets and used a lot of carb cleaner and gas and used compressed air to blow them out. I also had a lot of problems trying to get on line with the serial number to find parts. I wrote the wrong number down. I missed the last or first number because it wasn't written as clearly as the rest. Check the number again. Good luck. By the way, after we got it running again the impeller was bad also and that took more time to get one down here. So you may want to buy another also. I have a spare now in case I need it later.
edit:
Here's my SN, B A L J 1302034 yours should have the same amount of letters and numbers.

[Edited on 1-15-2017 by Russ]




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[*] posted on 1-15-2017 at 01:41 PM


Jim
I don't have one of those motors but the part you broke looks a lot more like an idle jet than the brass plug with the green ink on it does. If it was me and I had any more problems finding parts I think I would just get a new carb. You also might just try running it like it is and just raise the idle speed a little so it doesn't die so easy. Good luck with it. When are you coming down next?
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[*] posted on 1-15-2017 at 01:56 PM


I have never worked on an outboard but do have lots of experience working on motorcycles, so with that in mind....

I suspect the screw you tried to remove is the idle circuit mixture needle valve. It controls either the amount of fuel, or alternately amount of air being introduced into the idle circuit and as a result adjusts the air/fuel ratio of the idle mixture. If is very common for the tiny passages to become clogged, even a thin layer of fuel varnish deposit can have an impact. And don't even get me started on what they are calling "gasoline" nowadays, I just refer to it as fuel.....

If the adjustable needle valve is before (air intake side/away from the engine) the throttle valve (plate, slide, butterfly) the idle mix is adjusting the amount of air, the fuel being fixed. If the needle valve is after the throttle (nearer the engine) it is adjusting the amount of fuel mixed with a set/fixed amount of air.

Why is this important? Because the difference affects what you are adjusting, air or fuel. If air, adjusting CCW = more air (leaner), CW = less (richer). On the other hand if fuel, CCW = more fuel (richer), CW = less fuel (leaner).

In the MC world (and I don't know why), 2 cycles use a needle valve that adjusts the amount of air, and 4 cycles use a needle that adjusts the amount of fuel. Also very common for the adjuster to have a range limiting cap (as you found) pressed onto the needle valve. This is intended to limit the adjustment range, mostly for emission reasons.

It looks to me like the brass needle is seized to the aluminum or pot metal of the carb body, which is something of a problem.

If I had to guess and I do, the brass with the blue marker is likely the air inlet to the idle mix circuit and looks ment to be fixed because it appears to be pressed in and has no markings as to size. I suspect there is a serviceable idle jet inside the carb. On an MC it would be in an area where fuel flow/level is maintained called the float bowl. I don't know if outboards use a float bowl type carb or not.

Russ is 100% correct, for cleaning I like an aerosol can of Seafoam and a soft strand of copper/brass wire (a strand from a power wire or a brass wire brush). Better yet is installing new jets or cleaning old in an ultrasonic cleaner.

Unfortunately I think you have yet to get to the problem area (inside the carb) and have found the idle needle jet is seized (and now broken). IMO it's well past time for someone who knows how these work to look at it. Sure doesn't sound to me like you have found anyone yet who does.

You could order a new carb but in my experience anything that is fuel or emissions related is ghastly expensive. If you could source a used carb, it would likely benefit/require a thorough cleaning as well. It is possible that with a good cleaning /overhaul your carb would be OK, but the idle mixture adjustment is no longer ajustable do to the seized needle valve. I have heard of folks being able to remove seized/damaged bits from carb bodies but most fail, the result being a junk carb.

Best of luck, hope you find a fix.
Bruce
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[*] posted on 1-15-2017 at 02:42 PM


reality is...

you tried to fix it ...you broke it...

you won't get someone to rebuild it for less than $200 so you should probably just get another and bolt it on...$200

you really don't want your motor to stop running when you are "out to sea"...its not a good day when that happens

it's a LONG row home




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[*] posted on 1-15-2017 at 04:00 PM


I had an older Johnson two stroke that had a similar problem, troll fast or die! In my case the problem turned out to be the coil, not the carb.



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[*] posted on 1-15-2017 at 04:02 PM


I had a sailboat with a 90's(?) Honda BF10. It had a similar problem, and after cleaning the carb thoroughly a couple times, I could never get it to idle right, as it would stall when trying to dock, or right when putting it in gear. A total nightmare getting out of the slip.

Ended up getting a dinghy with the same motor, and put the carb from it on the sailboat motor, problem solved. You may get people to take your money trying to fix it, but you should just get a new carb, or try another used one. I tried adjusting the air screw, but could never get the problem resolved. The damn thing ran fine under power, just would never idle, and raising the idle speed was good in a pinch, but hard on the final drive getting in gear. I don't recall it having a replaceable idle/pilot jet.

I've rebuilt dozens of carbs, and that one stumped me. Those little engines can be really finicky to get idling correctly.

Santiago, try a small left hand drill bit to get it out.

[Edited on 1-16-2017 by BajaBreak]
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[*] posted on 1-15-2017 at 04:07 PM


My short version is... it likely just needed a thorough cleaning but now also has a broken idle needle valve. If the needle design is like others I have seen, there is an "O" ring still sealing the shaft so may still function OK, just no longer adjustable.

If a replacement carb is not feasible (OEM motorcycle carbs are hundreds of $) I would get someone with the knowledge to disassemble and thoroughly clean. While apart, note if idle jet is replaceable, it's style and the size stamped on it.

Try the motor after cleaning, if is OK you are done......and if not order a new idle jet one size richer and install.....probably run better than ever due to stock being emissions lean.

Bruce
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[*] posted on 1-15-2017 at 04:13 PM


captkw where are you? :?:
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Santiago
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[*] posted on 1-28-2017 at 01:13 PM


Ordered new carb and installed today, first pull fired up and idled perfectly. Ended up buying the shop manual for security but really didn't need it. I'll break down the old carb to see if I can discover the problema.
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[*] posted on 1-28-2017 at 01:28 PM


It's good to hear you'll be able got go play on the water.



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[*] posted on 1-28-2017 at 02:00 PM


now just put an in-line filter from the tank to the engine and probably wont happen for awhile...
lots of dirt goes in the tank during filling

just put the old carb in a plastic bag and throw it in the tool box for later




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