Hi Patrick,

I have a Honda BF9.9AXSA outboard motor, model year 2000.  I use it on my Walker Bay RIB.  If you have a compression tester, you can quickly determine the status of your piston rings and valves.  The factory compression spec is 156 +/- 14 psi when the engine is cold.  If your compression meets spec in both cylinders; then, your piston rings and valves are OK.  If the compression values are low; then, squirt some engine oil into the spark plug hole on each cylinder and retest the compression.  If the compression improves; then, you have worn/stuck piston rings.  If the compression does not improve; then, you have valve leakage issues.   The only way to fix valve leakage is with a cylinder head rebuild.  However, since your engine still runs, if your problem is stuck piston rings; then, you may be able to free them up.  Drain out about ½ the crankcase oil and refill with a product like Slick 50 Synthetic Oil Treatment.  Squirt some Slick 50 into each spark plug hole, gently crank it over a few revs, and then let it sit overnight.  The next day, start the engine, and let it run at idle for 15-20 minutes.  Then, shut it down and change the oil.  Hopefully, this will free up the piston rings.  I don't have much faith in any fuel additive's ability to free up stuck piston rings.

My M/Y 2000 engine has a crankcase vent that dumps directly to the atmosphere via a rubber hose on the port side.  The crankcase breather cover sits just in front of the timing belt sprocket on the top of the engine.  I've never had my breather cover off because I've never needed to get in there.  However, given that it vents to the atmosphere, I doubt there is any sort of PCV valve that might get stuck or clogged.  However, I suppose it's possible the vent port itself &/or the hose might be clogged.  So, it might be worth a look underneath the breather cover just to verify that the plumbing is free and clear.

Try these suggestions and let's see what happens.  Good Luck!

Roger Pihlaja
S/V Dynamic Equilibrium
1978  Sanford, MI

________________________________
From: Rhodes22-list <rhodes22-list-bounces at rhodes22.org> on behalf of Michael D. Weisner <mweisner at ebsmed.com>
Sent: Tuesday, April 2, 2024 2:12 PM
To: 'The Rhodes 22 Email List' <rhodes22-list at rhodes22.org>
Subject: Re: [Rhodes22-list] Honda BF9.9 Oil from carb

Patrick,

I think that if you have a problem with "stuck" piston rings, you would know it. I would suspect that there would be a loud noise and the engine probably would not run at low speeds as it seized up.

My guess is more a problem with the crankcase ventilation system. Usually there is a PCV style one-way valve that sucks oil fumes out of the crankcase, burning them by introducing into the air intake. Check the air filter which is usually part of the recirculation circuit as it can become saturated with oil.

Is the engine consuming oil? Have you checked the oil level using the dipstick? The smoke and excess oil can be the result of worn (not stuck) piston rings or valves that are allowing the oil to pass into the combustion path.

Mike
s/v Wind Lass ('91)
Nissequogue River, NY
I’d rather be sailing :~)

-----Original Message-----
From: Rhodes22-list <rhodes22-list-bounces at rhodes22.org> On Behalf Of PBR
Sent: Tuesday, April 2, 2024 1:52 PM
To: rhodes22-list at rhodes22.org
Subject: [Rhodes22-list] Honda BF9.9 Oil from carb

Hello all.

I have a Honda 9.9 2 cyl.  that has been mostly sitting for a few years.
It sat on the boat in Kitty Hawk (humid environment) for one winter untouched (2018).  Since then I have not used it on the water but always expecting that I might anytime soon I did not winterize but dutifully started it every couple of months throughout the winters and ran it a bit with the water hose.  Always started easy and ran good.  Some smoke at first but not enough to concern me.  This time as I was about to put the thing in to use I put a bucket (trash can ) around it and ran it again.
Started easy , runs good, again some smoking, enough to get me curious but not constant at all speeds.

Looking under the cowling I see oil dripping from the carb intake (clean golden oil).  Still running fine.I am hoping there may be a *vent clog* or something rather than just frozen rings.  Any thoughts?  *Stuck valve?* ( but runs pretty good)

This 1999 motor has VERY VERY low miles and looks brand new so I hate to scrap it but given the date of manufacture the value is probably less than a marine repair will charge me to take a look.  Hoping for a miracle solution.  Twice I have removed mud dauber bee nests from under the cowling so maybe I can find something suspicous.

The trash can I ran it in did have some residual oil clinging to the sides but I don't know how much might be normal.

My plan next trip in a couple of weeks is to look for clogs and try running again maybe with a high dose of sea foam or something.  Not sure of any miracle sauce that might help stuck rings.

Patrick