MacGregorSailors.com

Oh..
Awesome service manual post!

The plugged (covered) screw is an air/fuel mix adjuster. I've never had to touch it.

I used to get my rebuild kits from boats.net.

Most cases they are ok..
I had one carb bunged up...
AD

So, thanks to you guys, I took a bit of a deeper dive to figure out what the boat mechanic was talking about... I found the putty, and what part it's holding together. It's available from boats.net ... Well, let me show you guys what it looks like, and you tell me what you think:



I found the part that's puttied in, and it looks like it's a simply screw set. The putty is hard, like it's holding it in. I don't know what this particular screw does for the engine, nor does it make sense that it would cause a cylinder to fail... I suppose the $7 could be worth it to find out.

Identified as screw set #5 : https://peparts.honda.com/marine#/brows ... F50A5-SRJA

https://www.boats.net/product/honda/160 ... gJ__vD_BwE

To folks other than the original poster, Kingtoros, the best advice is from BeFree above. Never touch the mixture.

To Kingtoros: I did a websearch to add to the discussion. I found this link for you:

https://forums.iboats.com/threads/adjus ... el.355747/

You might as well figure on taking off the whole carb assembly and go through everything, since whoever did that goop mess on the jet screw may have bungled something else.
Let us know when you do and lots of us have advice on carbs for you.

opie wrote: ↑Thu Oct 28, 2021 3:26 am the best advice is from BeFree above.

It was late last night, and I didn't read back before posting the photos. Thank you for this reminder as I looked back, more than a couple of you guys correctly identified this as the pilot screw, or the possible issue.

I ordered one and will keep you posted how my carb troubleshooting goes.

Thank you, Thank you, Thank you

Wow..

Putty!?

Not sure why anyone would put putty?!
Anyways.. if the fuel mix is off.. it can easily be adjusted back... or cleaned.. its NO big deal to tune the fuel mix.
(all older carbs had this adjustable and jets replaceable) Locking/plugging it is for emissions.. so you do not alter the mixture and pollute..

Wondering if they stripped some threads on one of the jets..then puttied it up to hold it in place.
Thus a new carb (or old one that you use for parts off ebay) is in order. Usually the last (3rd) carb is a bit different.. make sure you get the correct one you need.

Not a huge $$ anyway.. maybe around $200 us..

But it appears that someone was messing around.. and did a hack repair.
(remove the putty.. see what happens.. does the jet fall out?)

kingtoros wrote: ↑Thu Oct 28, 2021 3:51 am

opie wrote: ↑Thu Oct 28, 2021 3:26 am the best advice is from BeFree above.

It was late last night, and I didn't read back before posting the photos. Thank you for this reminder as I looked back, more than a couple of you guys correctly identified this as the pilot screw, or the possible issue.

I ordered one and will keep you posted how my carb troubleshooting goes.

Thank you, Thank you, Thank you

Yep, that's the one that you really don't ever need to mess with. If I remember correctly the top of it actually breaks off when you remove the cap.

Man, I've taken apart, cleaned, reinstalled, synched and forgotten more about BF40/50 series carbs than I care to admit but the advice you've been given here has been tremendous. These things were so finicky that they have entire manuals on JUST cleaning the carbs. I'm pretty sure I have them in electronic format... give me a day or two and I'll see if I can't scrounge them up and either post them here or email them to you.

As for synching the carbs, here's a link to a video on a BF40 that shows you exactly what you need to do. https://youtu.be/bsHCMJnRY9A

edit: here's the pdf of the BF40/50 service manual. I'll have to dig deeper to find the carb specific manual but this is pretty comprehensive and you'll learn a lot about your engine. So long as you have good compression and enough time to tinker with the carbs from time to time, these motors will run forever.

Ahhh.. Danger Marine..
Good channel.
EXACTALLY what you need to do after a carb job.

I can't tell you how many times I watched Danger Marine's video on carb tuning... It starts off with "Oh My Gawd what did I get myself into, I'm never going to be able to do this" and by the end, the guy's got me convinced it's going to be A-Ok.

Well, I have an UPDATE!

Special thanks to NiceAft and taylormade, your books and excerpts were the ticket.

Pilot screw on the #2 carb was set at exactly 2 1/8 turns out, before being slightly tuned per Danger's guidance.

Then got the exact kit on Amazon I found posted here in another thread about carb balancing. The dry dock trials yielded hugely positive results. Hopefully be able to put her in the water in a few weeks for sea trials. I debated putting the cap on it, but my buddy suggested it might benefit from it for stability, and at $8 for a pilot screw placement, it's not a bad sacrifice.

Here's it installed and a comparison of the two screws:

Yes, syncing the carbs will make a HUGE difference.
One trick.. determine what RPM you normally cruise at.
(ie: 2000rpm is your usually speed/rpm when motoring)

Connect your meter... to the vacuum ports.. rev up to 2000rpm (make sure engine is fully warmed up)
(Best if you do this in gear under load.. but may not be 100% practical)
And sync the vacuum there at that rpm.. Using the idle screws.. leave the bottom one.. adjust the 2nd and 3rd to match..
When all synced.. check if your at correct Idle RPMS.. if not adjust bottom one.. check/repeat

This way it will run BEST at your ideal cruise speed.. and you will bet best fuel burn as well.

The "PRO WAY" is to put the motor in a tank.. with a special prop.. and run it in gear .. but yeah.. NOT very easily done.

Myself.. I set it to idle.. as we often go up a local river, .. and its a no wake zone for miles... so I just idle alot..

At this point, I can pull/rebuild/clean/reinstall/sync my 4 pack of carbs in a good afternoon.. (in my slip in the water even)


AD

Another quick update here. The drydock trials were good, but as adudinsk alluded to, I set my idle rpm too low.

Two more things I'm going to try is to get a new (larger if it's not already the larger variety) fuel line from the moeller 6 gallon tank it comes from now and replace the fuel filter.

Oh, and a new prop...

Hoping to have all this done this month, and a final update on this crazy engine this year. Yamaha 70 HP is the same weight at $10k... Too bad my numbers didn't hit the Megaball