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Re: Honda 50 hp carburetor synchronization

Posted: Sat Jun 14, 2025 1:09 pm
by opie
AD and BeFree and others,

Thanks for your sympathy. Let’s make this post today start with a riddle:

When are 6 teeth worth $5000 to $10,000?

Drum roll….

When the teeth are set incorrectly for a Honda BF50A engine timing belt. 6 teeth “off.”

Short story: I fixed my Honda outboard today by readjusting the timing belt to spec.

Long story: (read if you don’t have drying paint to watch….)
1. Didn’t run last year but 2 or 3 times.
2. Put up without winterizing
3. Had cheap gas
4. Recently ran boat but it was obvious carbs needed cleaning. I have done it 10 times in 20 years.
5. Cleaned carbs but resused old parts that actually had a varnish on them. Still didn’t run right. I trusted my carb skills (mistake) and started throwing parts on the wall. Even though they checked out ohm-wise, I replaced the pulser, exciter and charge coils because they looked old. I bought new carb jet nozzles and main nozzles.
6. Engine ran worse.
7. Checked carb sync and only got 7” on each intake. Bad. Then I checked compression and got 40/30/10 psi.
8. Gave up.
9. Got four quotes on engines both 25 and 50 hp.
10. Wanted to pull trigger last week on Suzuki DF25.
11. Admiral said whoa! Go back and see exactly what’s wrong
12. I tell her that I wear pants (too…) and the local mechanic says my rings are rusted out by my description. I should have winterized I tell her.
13. Admiral says “no!” to new engine. I haven’t tried hard enough she nags (oops.. suggests)
14. Today I rethought things and especially the fact that I removed the flywheel and maybe moved the belt?
15. Went to boat. Yep. (After fixing timing belt the compression was 130/130/120, with a bit of sprayed WD40)
16. Came home and gave the Admiral the good news that the engine is fine and I gave her the praise she deserved.

Re: Honda 50 hp carburetor synchronization

Posted: Sat Jun 14, 2025 1:11 pm
by opie
I will reuse my new synch tool Monday and report back here on my adjustments.

Re: Honda 50 hp carburetor synchronization

Posted: Sat Jun 14, 2025 5:19 pm
by kmclemore
Well done!

I did the belt on my 2004 Toyota Sienna... it was a ROYAL PITA, given that there's only about 3" to work in with that big transverse V6 in there. Anyway, after installing the belt it seems I got it off by a tooth... the engine ran, but ran like crap, with a lack of power. Went back and checked the belts and, sure enough, I had screwed the pooch. Fortunately, it's not an interference engine, so no valves slammed any pistons. I reset the belt and the power returned (whew). Added about 2 hours and 3 more cuts in my hands, but job done and still good today, at 258,000 miles.

Re: Honda 50 hp carburetor synchronization

Posted: Mon Jun 16, 2025 6:22 am
by adudinsk
Great News..
Time to promote the Admiral..

I would be curious how "off" your carb sync was. And if it smoothed out the OB.

Also if you get a bit of Sputtering at higher RPM that could be the float in the carb(s) not properly set.
(mine had that)

I did repower anyway... wife.. err... cabin girl.. gave me the OK.
(had to buy her new bedroom set/appliances/hardwood floor upstairs /carpet in basement.. so she got the better of the deal.. .LOL)

Did a prop test with no ballast on Wednesday.. Dialed in a 11 1/2" x 13 pitch. Pushed to about 5500rpm (checked on tack/and computer)
Not sure how fast we were going.. but were up on plane.
(need to install/mount my Raymarine Axiom 9+ soon)

The guys from the shop were fantastic.. came out.. went for a ride..
I was told that after the 20h break in period... I may even get 2-300 rpm more out of the DF60A I installed.

Yeah.. it cost.. but I have no worries now, and will be burning MUCH less fuel than my old carb'ed engine.


AD

Re: Honda 50 hp carburetor synchronization

Posted: Mon Jun 16, 2025 7:08 pm
by Be Free
Opie,
I am very happy that you don't have to go to the trouble and expense of replacing your engine.

I wonder if you realize how lucky you were! Unlike Kevin's Toyota, your BF50A IS an interference engine. You could have put one or more valves through the top of one or more of your pistons the first time you cranked it!

Question for all:
Should Opie go out and buy a lottery ticket since he's obviously a very lucky guy or did he use up all of his luck on the engine? I've never heard a persuasive argument for either position. :|

Re: Honda 50 hp carburetor synchronization

Posted: Tue Jun 17, 2025 4:53 am
by adudinsk
Yes.. time to buy a Lotto Max...

Re: Honda 50 hp carburetor synchronization

Posted: Fri Aug 08, 2025 5:46 pm
by opie
It has been 2 months since I planned to do the carb sync. Life got in the way and today was my first chance to see the boat at the storage yard. Here is the video. All good. Sea test soon.

https://youtube.com/shorts/9GlEbJEN5V8 ... KoWTQIlgiu

Re: Honda 50 hp carburetor synchronization

Posted: Wed Aug 13, 2025 4:53 pm
by opie
I can close out my thoughts now in this thread after my sea test today. I ran all speeds and up to WOT. All good. A few days ago the synch tool showed a slight sag in the middle cylinder. I followed the directions and they are now all even. I’m at 8” Hg vacuum. But the boat seems as strong as ever. Common web talk seems to say I need 12 to 15” Hg vacuum. But I am satisfied with the pudding and will not mess with anything.

Re: Honda 50 hp carburetor synchronization

Posted: Wed Aug 13, 2025 5:50 pm
by Russ
Wow. Good work!

All that sounds complicated. Glad you got good results.

Re: Honda 50 hp carburetor synchronization

Posted: Wed Aug 13, 2025 7:23 pm
by Be Free
Glad to hear it all worked out. Thanks for the follow up.