Need some help/rough idle

[Newbie@boats]

This is on my 2000 Yamaha 50HP 4-stroke

Last time I had the boat out it ran excellent besides one hiccup(misfire/running rough for about a minute)

This time took it out and it was hard to start but ran like a clock above 1500 RPM but at low idle it'd be rough and die.

Realized the gas tank wasn't venting air and released it and boat seemed to be better but problem still presented itself.

Got home and realized the choke when you push the key in wasn't doing anything no clicks or anything disconnected it and applied 12V and it clicks so I don't think it's a bad solenoid. Where should I go from here? Would that cause an issue even if the engine is warm from going to fishing spot to fishing spot?

Idle would be at like 600/700RPM before I go and start trying to raise the idle what do you guys think? Thanks!

[99yam40]

clean the carbs. jacking with adjustments does not do anything to fix the problem the motor has

[Newbie@boats]

According to the PO the carbs were just done how true it is who knows.

Would I need carb kits?

I've cleaned the carbs on my old merc 150 and on many many other machines these look like one of the more difficult ones to clean.

Should I try to adjust the air/fuel screws ?

I screwed in one to see how many it was out and it was only about a turn out.

From what I read they should be 1 7/8 turn out?

[99yam40]

I am thinking the 4 strokes need a multi channel manometer to set them properly.
who did the carbs and did they follow the proper procedures for adjusting after they put them back on

even if it ran well after the carbs were done, if trash hits the carbs after they are put back on, they will need to be cleaned again

[Newbie@boats]

Got all the carbs apart and soaking in carb cleaner. Will let them soak for a couple of days and see what happens.

Does anyone know what the air/fuel screws need to be set at?

They were all in different positions.

[99yam40]

I would recommend get a Yamaha service manual for your motor.
it will have all of the specs and tell you what equipment you need to do things properly

maybe someone with a manual for your motor will see your post and help.

sounds like the carbs may not have been done properly last time

[Newbie@boats]

Heres what the carbs looked like taken apart.

[Newbie@boats]

Once I get the carbs cleaned and gone thru I will order this

https://www.amazon.com/ABN-Carbureto.../dp/B00T80OR52

And sync up the carbs and see if it runs any bette

[panasonic]

Once I get the carbs cleaned and gone thru I will order this

https://www.amazon.com/ABN-Carbureto.../dp/B00T80OR52

And sync up the carbs and see if it runs any bette

Had a set similar to that for synchronizing carbs on motorcycles. They are usable but the gages bounced around a lot. Replaced the gages with liquid filled ones and they worked much better.

The old mercury filled tube types worked great but you had to be careful not to Rev the engine to much and suck mercury into the engine...lol

[Newbie@boats]

Got the carbs all cleaned out today and reinstalled on the boat.

Not going to run them until I can 100% dial them in

I figured out how to set the air/fuel screws.

Just waiting on the carb sync kit to arrive hopefully be back on the water this weekend!

[Newbie@boats]

Quick question guys......

I got the tool today and will sync them tonight.....

I have heard conflicting stories here....

I assume the lowest carb will be the carb I want to sync the top 3 to

From what I gathered is start boat let warm up....hook up sync gauge and set idle to 950/1000 RPM using the screw on the lowest carb since that one will adjust all carbs, then sync them all together using the screw on each carb for the butterfly valve then I set air/fuel screw properly.....I am sure I am over thinking this but anyone think im on the right track? Thanks!

[TownsendsFJR1300]

*Looking at the parts fisch: http://www.boats.net/parts/search/Ya...TOR/parts.html
it appears the lowest carb has the main idle adjustment STOP screw, so I'd agree with your assessment.

W/O having the service manual, I start closer to normal idle, it shouldn't be hard to get them very close and fine tune for vacuum and get the idle to normal spec's.

Syncing most carbs, your basically setting ALL the butterflys so their all pulling the same vacuum at idle. You can also rev it some (and hold steady RPM's), to a point. Once the butterflys open quite a bit, it's not nearly as critical...

If you know the base idle air screw adjustment #, I'd set all at that # to start with.


Did you PULL the main and idle jets on each carb and inspect?

IE, See light thru each?


.testetetet

[Newbie@boats]

Yes I actually downloaded a repair manual for $10.00 and it has all the info right in it. Shouldn't really be to bad to do at all. It tells me the base spec and pretty much match them up to that. It wants it to be done with the engine idle at 1000rpm then sync them then adjust pilot screws and according to the manual they were WAY off from the specs. About 1 turn out when the manual says 2.5/2.75

Yes I throughly checked the carb jets and cleaned them with a massive amount of care to ensure I was only doing this once.

[TownsendsFJR1300]

Sounds like your good to go!

Good luck.. And those air screws being off so much can cause idle issues...

[panasonic]

The sync kit you got, did the needles on the gages jump around alot.?

I lent mine out a few years ago and never got it back, and cannot remember who I gave to....grrr