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Honda 25hp outboard four-stroke 2007 running ruff.

Dean0

Member
It sat two months started it running ruff soaked carburetors no change pulled plug wires off while running bottom cylinder no change replaced coils no change replaced cdi no change plugs no change. Can it be the coil power under the flywheel. Oh all cylinders are getting spark that's why I went the way of a fuel problem oh did put a new fuel pump. I'm completely lost on what's next. Oh did a compression test top cylinder 125 middle 145 and bottom 145. The bottom cylinder is the one given the problem. Thanks for any suggestions or information.
 
I will agree with racerone. If that cylinder has good spark and compression then it's likely that there is an issue with the bottom carb.

These carbs can be difficult to clean and they have critical components and orings that need to be carefully inspected and replaced when necessary. It's usually not sufficient just to "soak" them. Whatever that means.

If you really want to get it right the FIRST time, buy and read the Honda Marine Carburetion Manual available at the link below under "support materials":


:https://publications.powerequipment.honda.com/marine

Good luck.
 
Agree with above .... I have a fleet of bf25 s .... idle circuit very difficult to clean properly without an ultrasonic.... also carb balance.
 
I will agree with racerone. If that cylinder has good spark and compression then it's likely that there is an issue with the bottom carb.

These carbs can be difficult to clean and they have critical components and orings that need to be carefully inspected and replaced when necessary. It's usually not sufficient just to "soak" them. Whatever that means.

If you really want to get it right the FIRST time, buy and read the Honda Marine Carburetion Manual available at the link below under "support materials":


:https://publications.powerequipment.honda.com/marine

Good luck.
Thanks.
 
Agree with above .... I have a fleet of bf25 s .... idle circuit very difficult to clean properly without an ultrasonic.... also carb balance.
Thanks. Do you know if the idle tube that runs down the middle of the carburetors is Hollow down the center all the way through I can run a cleaning tool from top almost all the way thru but stops just before coming out the bottom just curious it's it's blocked? All three are that way it leads me to think there not supposed to be hollow but not sure. Thanks
 
If you're referring to the slow jet emulsion tube or "jet set"....item 25 in the link below:


YES! The tube is supposed to be "open" all the way down. BUT....DO NOT TRY TO FORCE A CLEANER FILE THROUGH IT.!

Because, what you're encountering is the actual reduced diameter of the jet itself.
Any attempt at "gouging" out the jet with a tool or wire usually only results in damage to the jet.

If you can't clear that orifice with carb spray. I highly recommend that you replace the tube with a new one.

That tube and it's little oring have a major role in how the carburetors function. If you can't get it totally clear with carb spray but try to reuse it, you will likely find that you'll soon be pulling the carbs off again real soon.

I KNOW....not what you want to hear but that tube has bitten most of us that have worked on these.

I used to do these carbs weekly and used an optiscope with 40× lens to clean that tube because the jet is so hard to look through. BUT...I finally realized that they just weren't worth the trouble. I decided to just stock new ones and swap em out to make my life easier and the work go quicker. Your choice though.

In addition to the jet and all holes needing to be perfectly clear, that tube also has a tendency to crack and split up the side. So watch out for that too.
 
I will agree with racerone. If that cylinder has good spark and compression then it's likely that there is an issue with the bottom carb.

These carbs can be difficult to clean and they have critical components and orings that need to be carefully inspected and replaced when necessary. It's usually not sufficient just to "soak" them. Whatever that means.

If you really want to get it right the FIRST time, buy and read the Honda Marine Carburetion Manual available at the link below under "support materials":


:https://publications.powerequipment.honda.com/marine

Good luck.

If you're referring to the slow jet emulsion tube or "jet set"....item 25 in the link below:


YES! The tube is supposed to be "open" all the way down. BUT....DO NOT TRY TO FORCE A CLEANER FILE THROUGH IT.!

Because, what you're encountering is the actual reduced diameter of the jet itself.
Any attempt at "gouging" out the jet with a tool or wire usually only results in damage to the jet.

If you can't clear that orifice with carb spray. I highly recommend that you replace the tube with a new one.

That tube and it's little oring have a major role in how the carburetors function. If you can't get it totally clear with carb spray but try to reuse it, you will likely find that you'll soon be pulling the carbs off again real soon.

I KNOW....not what you want to hear but that tube has bitten most of us that have worked on these.

I used to do these carbs weekly and used an optiscope with 40× lens to clean that tube because the jet is so hard to look through. BUT...I finally realized that they just weren't worth the trouble. I decided to just stock new ones and swap em out to make my life easier and the work go quicker. Your choice though.

In addition to the jet and all holes needing to be perfectly clear, that tube also has a tendency to crack and split up the side. So watch out for that too.
Omg thanks I appreciate 💯% that reply I thought they were supposed to be open I'm gonna go through them again I will let you know what happens. Big thanks again. I did replace the orings on them when I went through them just the other day. I'll probably just end up getting new ones. I'll let you know.
 
If you decide to clean them .... the orifice is very small at the opposite end from o-ring..... about .010 inches if I recall.... what I use to clean is a single strand off a bicycle brake cable.
 
The orifice size is stamped on the upper end of the tube. It should be 40 in this case which is 0.40mm

Translated to thousandths of an inch that's 0.015".

These carbs are "cascade flow". Meaning that, to provide maximum fuel at full throttle, all circuits... ie: idle, transition and high speed supply fuel at WOT.

It's important that the main air jet and slow air jet are clear. Cleaning those is often overlooked. Those jets are deep inside the main body and are cleaned via the two drilled passages on the front mount flange.

I also recommend "backflushing" each circuit orifice above the throttle blade individually then "foreflushing" through the main and idle supply while observing for flow from each orifice. Flushing more than once, or more, back and forth, is best for a very dirty unit.

Make certain that the bystarter feed channel at the bottom of the #1 (top) carb float chamber is clear. That is often packed with dirt.

I'll say....ONE MO TIME...that...
The Marine Carburetion Manual is worth every penny. AND....it's the same price it's been for 3 years or more. But I bet it's going up in the very near future.

Good luck.
 
The orifice size is stamped on the upper end of the tube. It should be 40 in this case which is 0.40mm

Translated to thousandths of an inch that's 0.015".

These carbs are "cascade flow". Meaning that, to provide maximum fuel at full throttle, all circuits... ie: idle, transition and high speed supply fuel at WOT.

It's important that the main air jet and slow air jet are clear. Cleaning those is often overlooked. Those jets are deep inside the main body and are cleaned via the two drilled passages on the front mount flange.

I also recommend "backflushing" each circuit orifice above the throttle blade individually then "foreflushing" through the main and idle supply while observing for flow from each orifice. Flushing more than once, or more, back and forth, is best for a very dirty unit.

Make certain that the bystarter feed channel at the bottom of the #1 (top) carb float chamber is clear. That is often packed with dirt.

I'll say....ONE MO TIME...that...
The Marine Carburetion Manual is worth every penny. AND....it's the same price it's been for 3 years or more. But I bet it's going up in the very near future.

Good luck.
Thanks lots of great information here. I did take the bystarter out and spray it. I'll completely check it again. Very good information I appreciate that 👍.
 
If you decide to clean them .... the orifice is very small at the opposite end from o-ring..... about .010 inches if I recall.... what I use to clean is a single strand off a bicycle brake cable.
Ok I did notice that none of my cleaning tools would go through the end none are small enough thanks.
 
I was referring to the little bystarter FEEDER channel in the bottom of the float chamber bowl. If that little passage is plugged or partially plugged, you will have cold start problems.
 
I was referring to the little bystarter FEEDER channel in the bottom of the float chamber bowl. If that little passage is plugged or partially plugged, you will have cold start problems.
I will look for it it was given me trouble cold starting after It warmed up started just a click of the starter. I appreciate this information very helpful for sure 👌
 
I will look for it it was given me trouble cold starting after It warmed up started just a click of the starter. I appreciate this information very helpful for sure 👌
Hi just wanted to give you a update I pulled all the jet sets two are flowing good the bottom one is cracked at the bottom where the main jet is. I'm going to go see about getting one now I'll keep you posted thanks again for the great information oh the bystarter passages are clear sprayed carburetor cleaner everything is flowing thanks
 
Sorry to bother you again how do I know what one I need or does it matter? My motor is a 2007 25hp Honda four-stroke. Both of these are #40. Confused again lol. Can definitely see the crack on this one.
 

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I will agree with racerone. If that cylinder has good spark and compression then it's likely that there is an issue with the bottom carb.

These carbs can be difficult to clean and they have critical components and orings that need to be carefully inspected and replaced when necessary. It's usually not sufficient just to "soak" them. Whatever that means.

If you really want to get it right the FIRST time, buy and read the Honda Marine Carburetion Manual available at the link below under "support materials":


:https://publications.powerequipment.honda.com/marine

Good luck.
Hi Jgmo just wanted to check in with you and thank you for the great information it was the jet set it was cracked at the bottom just put a new one this morning and it's back to perfect just need to fine tune the carburetors it's got a hesitation when reving fast. Thanks again. 👍👍
 
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