Replacing the needles in a carbureted USA model 50HP Honda

[MattFL]

Can anyone tell me where to find the actual serial number on a 50HP Honda? I've got he frame number and model number, but I can't find the "serial number" anywhere. Here's the motor info:

And I'm trying to buy a part that is different depending on the engine serial number, but I can't find the numbers they mention anywhere:

 

[ahicks]

I've never seen any number (or maybe paid attention to) using that format on a Honda. The only other number of any consequence is on the block, located near the bottom of the starter - impossible to read without removing the starter.

I just went out to look at a 98' 50 hp, another BAZL something or another, that I happen to have here. This motor runs perfectly, and uses the screws you're after. In fact, the outfit I use for parts shows the new type in use, with those same 2 choices,clear back to the '95's, which uses the screw I have in my 50. That would be the original screws with no cap. Those are part# 16016-ZV3-000

which are the ones I would order if I were working on your motor.

Best of luck getting your question answered. -Al

 

[durban]

Your frame no: falls within the year 1999 BF50AX models.

 

[MattFL]

Yes I've never seen those numbers either and I have no idea what they're referring to? In any event, I wonder if the screw head is the only difference between then one you're using and the one that is listed for my motor:

For mine:
https://www.**********/product/honda/...a4124e03d45b7b

Yours:
https://www.**********/product/honda/16016-ZV3-000

I think I'll take the gamble that the needle taper is the same or close enough and order 3 of the one you're using and give them a shot. Thank you for the part number, and wish me luck!

I'm not sure if those links will be clickable here, so here are some pictures just in case. You can see the little tab is definitely a press-on part.

 

[ahicks]

From a performance perspective, one needle vs. the other, there's very little to concern yourself about. If you can get them to adjust correctly allowing a good idle, they're good to go (I start at about 2.5 turns, will end up anywhere from there to 3t as a rule).

Anything over an idle, and you're on the low speed jets, with these screws pretty much right out of the picture.

 

[MattFL]

This thread should probably be renamed to something about replacing the needles in a carbureted USA model 50HP Honda.

But it worked! Thank you very much for the needle part numbers. I tried pulling the caps off of the screws but that did not work at all. So I put the end of a pair of needle nose on the side of the screw cap and bumped it with my hand, and the ends of the screws broke right off, surprisingly easily. Then I used an easy out to remove them. 2 of the 3 came out so easy that the drill part took them out, I didn't even have to switch to the screw extractor side. Initially I was concerned that there wasn't much metal there for the easy out to bite into, but after getting them out you can see that there is actually a lot of metal there. I put the new screws in and at 2.5 turns out the idle appears to be more stable than I ever remember it, and the exhaust is a much different, crisper sound. The linkage that connects all 3 carburetors together seems to be worn (probably a couple thousand hours on this motor) so I'm going to get a new one of those and try to balance the carburetors, and maybe just maybe this thing will have a good idle for once in its life!

 

[GA_Boater]

replacing the needles in a carbureted usa model 50hp honda

You got it.

 

[ahicks]

Balancing the carbs on one of these isn't required very often, but if you can't get it to settle down nicely, the time and trouble to do that carefully can leave you with an engine that will REALLY idle - like only a 3 cylinder can.

The throttle return springs are holding the throttles against their stops on idle, so a sloppy linkage, as long as it's not binding, shouldn't affect your idle settings. What happens from there on up to full throttle is where a really sloppy linkage might come into play if it were not opening the carbs by equal amounts

Glad it worked out for you! -Al

 

[MattFL]

The idle changes significantly (100-200 rpm) if I rotate the linkage from side to side, so it appears the linkage and/or the balls on the carburetors are no longer round. So as the engine runs and vibrates, the linkage rotates back and forth, and after a run you never know if the idle will be high or low. I'm crossing my fingers that the new linkage helps with this. I somewhat balanced the carbs in the past by backing the idle all the way out to fully close the bottom carb, then adjusted the screws on the top 2 carbs until they were just starting to move, then turned the idle back up. It wasn't perfect, but was good enough. I'll try that again and if it doesn't work then I'll have to acquire some gauges and do it the right way.

We had it out this past weekend and it definitely runs a lot smoother down low with the new fuel screws! I was able to keep a steady 1000-1200 rpm for slow trolling, previously this was much more difficult. And bonus, it needs a lot less choke when cold. I'm not sure what the original screws were set at, but it was most definitely too lean.

 

[ahicks]

When warm and set correctly, these things will run stupid slow reliably. Under 1000 rpm and your getting there. 6-700 (in gear) and you're all the way home.

I just use the cheap vacuum gauges. I think I got my last set at Amazon for like 35 or so. (set of 4 in a case, with hoses and carb adapters).

The way you describe is a good starting point for sure. -Al

 

[MattFL]

Success I think! Not perfect, but very good. I had it out twice now, with long runs and lots of idling, and it idles without stalling around 700rpm in gear, not a single stall! Spec is 900 in gear I believe, so it should probably be turned up a bit. Maybe it could be smoother if I used gauges, but it's consistent and hasn't stalled yet so I'm calling it good for now. The method above wasn't all that great, it got the top two carbs close but the bottom one was way out. It's obvious by ear when one or more carbs are not matched, but it takes some fiddling to determine which are out of whack, and which way to adjust to bring them back. 1/8 of a turn on the screws makes a big difference. At about the 30 minute mark I hit the tipping point between gains and frustration and called it good. If I happen by some gauges I'll use them, but for now it's not worth buying them.