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honda powerhead adaptuiion

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wetsailor

New member
I "rescued" an 8 hp Honda outboard, pre 97. It had been submerged in salt water and left laying on the beach for who knows how long. I got it started and it overheated instantly. I turned it off immediately and tore into it. This covered that the salt and clogged all of the cooling passages. When I attempted to disassemble the power had the nuts and bolts were so hard to remove that I ended up breaking the head. I checked out the rest of the frame and was able to get all the cooling passages clear. I bought a 10 horsepower power head. I installed it and bought all new electronics due to the fact that it was a point ignition system. The eight horsepower power head with a CDI ignition system. The only thing that was not new on the 10 horsepower was the flywheel. I checked all the wiring, all other specifications, we timed it to factory specifications. It would not run. I set up a manifold to test the plugs outside of the head and I got sparks. I reinstalled the plugs into the engine and it still would not run. I removed the plugs and introduced a few drops of gasoline into the cylinders then reinstalled the plugs and I would not start I remove the plugs sprayed starting fluid into each cylinder, reinstall the plugs and it still would not start. I checked the magnets in the flywheel to be sure that they still had magnetic fields. They did. I then checked online to try to find out if I required eight different flywheel for a point ignition system. I read across many sellers that indicated they have a flywheel for a 7,8 or 10 horsepower Honda. I noticed black flywheels were for the.ignition system I noticed bread flywheels that indicated they were for the CDI ignition system. The flywheel that that was with the eight horsepower frame was black. I have checked and rechecked all the wiring checked and rechecked all the specifications for the different parts that are on the power head. Does anybody have any information for me at all? Any good guess's? The number on the power head is B 100 -1000 -820, the Honda frame number is BACL 1000542 mfg (1987), and is commonly known as a BF8A. I have found that the only difference between and seven and eight or 10 horsepower is the cam.
Thanks in advance for any help that anyone can get me I am at my wit's end.
 
It sounds to me as if you're overlooking something basic.
I mean if it has fuel, air and spark, it should BARK!

Does it sputter or TRY at all?
Remember...5 things for RUNNING:
AIR
FUEL
SPARK
And then the two things many of us tend to overlook sometimes:
COMPRESSION
TIMING....
Let's take the last one, timing.
Not only do the valves need to be properly timed...which you said you addressed....but make dang sure you didn't get it wrong. I saw no mention of valve lash being checked on the replacement engine and would do that if not done already.

The SPARK has to occur at the designed instant as well. While I had a bit of trouble completely understanding all that you wrote above (bread flywheels?) I saw no mention of the SPARK TIMING ADVANCE mechanism under the cam drive gear cover. The breaker points system uses a centrifugal weight advance while the CDI uses the PULSAR COIL instead. You don't have those things mixed up do you?
I'm not sure what the results would be if you did.

Depending on the ambient temperature that you're working in, putting gas or spraying starting fluid into a cylinder and THEN installing the plugs and plugging in the coils might not work as a valid fuel delivery test. Either one of those fuels would likely flash away before you pulled the string.
Testing with gasoline is "iffy" and can be pretty dangerous. I absolutely LOATHE the use of starting fluid (ether) unless it's a life or death emergency. I call that stuff the number one engine killer chemical available to the public. But...if you insist on using it....spritzing it into the intake immediately prior to pulling the chord is the way to do it.

I will always implore anyone working on gasoline engines to use PROPANE GAS when doing fuel delivery troubleshooting. It is EASY...SAFE...and will not harm the engine. It's STOICOMETRIC as it immediately mixes with ambient air. Meaning it runs gas engines beautifully without being explosive or needing to vaporize.
A simple plumber's torch will usually get the job done and, in convoluted intakes, it can be modified with flexible tubing to administer the fuel.

Ok, I will dismount the soapbox now and give you an opportunity to check out a few things...like compression...and get back to us.

Good luck.
 
Jgmo,
Thanks very much for your response. I will try what you have suggested and report back.
I missed the "edit" option on the post page, so here is a corrected post:
I "rescued" an 8 hp Honda outboard, pre 97. It had been submerged in salt water and left laying on the beach for who knows how long.
I got it started and it overheated instantly. I turned it off immediately and tore into it.
I Discovered that salt had clogged all of the cooling passages. When I attempted to disassemble the power had the nuts and bolts were so hard to remove that I ended up breaking the head.
I checked out the rest of the frame and was able to get all the cooling passages clear.
I bought a 10 horsepower power head. I installed it and bought all new "electronics" due to the fact that it was a point ignition system.
The eight horsepower power head had a CDI ignition system.
The only thing that was not new on the 10 horsepower was the flywheel.
I checked all the wiring, all other specifications, timed it to factory specifications. It would not run. I set up a manifold to test the plugs outside of the head and I got sparks. I reinstalled the plugs into the engine and it still would not run.
I removed the plugs and introduced a few drops of gasoline into the cylinders then reinstalled the plugs and it would not start. I removed the plugs, sprayed starting fluid into each cylinder, reinstalled the plugs and it still would not start.
I checked the magnets in the flywheel to be sure that they still had magnetic fields. They did. I then checked online to try to find out if I required a different flywheel for a point ignition system. I read from many sellers that indicated they have a flywheel for a 7,8 or 10 horsepower Honda. I noticed according to Honda, black flywheels were for the point ignition system, and red flywheels were for the CDI ignition system.
The flywheel that was with the eight horsepower frame was black. IOW, if I buy a flywheel for the 10 hp point ignition, I would get a "black", which I already have.
I have checked and rechecked all the wiring, checked and rechecked all the specifications for the different parts that are on the power head.
Does anybody have any information for me at all? Any good guess's?
The number on the power head is B 100 -1000 -820, the Honda frame number is BACL 1000542 (mfg 1987), and is commonly known as a BF8A.
I have found that the only difference between and seven and eight or 10 horsepower is the cam and possibly the flywheel.
Thanks in advance for any help that anyone can get me, I am at my wit's end.
 
You can't really go by the color of the flywheel on these old girls because many of them have been repainted over the years and your black 8 hp flywheel may have begun life painted red.
Have you tried the 8 flywheel on the 10hp to see if that works?
Other than that, I'm not sure why you're not getting any fire in the hole.
That's why I suggested what I did. You say you have spark....are you sure about that?...
If so. I'm thinking it's happening at the wrong time.
Keep up the fight and you'll figure it out.
 
ok. I did not get flywheel with the replacement powerhead, so I am using the 8 flywheel. I did think of the magnet placement, and went online to buy a 10 flywheel, but all the used ones listed were for 7.5, 8, and 10 hp motors inclusive, so I contacted Honda and they were no help at all, they wanted the serial number of the outboard, but I did not have the serial number for the outboard that the 10 hp powerhead came from.
I know that spark can be generated since I held the plugs outside of the head, grounded the threads to the head and spark was evident. I have checked and rechecked the timing according to the "Honda 7.5, 8 and 10 hp manual" and it is exactly correct. Thanks again for the reply, I still need to check a couple of other things you suggested and will report back later.
 
Look for your engine serial number on the 10hp stamped on the engine block. It's typically in the front but not always. It should be on the engine unless someone has filed or ground it off to cover a theft.

The red flywheel doesn't seem to be available anymore but there are two black ones that are still available. And, I believe they are BOTH used for CDI ignition systems so the red for CDI and black for breaker points "story" isn't absolutely true.

That's the trouble with this old stuff....I don't know what is true half the time because I got in on these late.
 
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