Feeling Stupid, Where's the Lean Screw?

[Dutch602]

Hi All,

New poster here, this seems to be a great forum. I have done plenty of reading, parts lookup, etc. and I'm struggling to find the lean screw on my carbs. Seems like it should be straight forward. Engine is an '87 Evinrude 150 - V6 with 3 carbs. I have a lean sneeze and lose a cylinder or two getting up to speed. I cleaned the carbs last year which didn't help, but I didn't adjust anything either.

Anyways, I think it should be #3 in the parts diagram, but when I look in the hole there's no head to turn. I don't think there's a screw in there, it's just a blind hole. Not a through hole though, I just see flat metal that abuts it a few inches down. This is the case for all 3 of my carbs.

Parts diagram and pics of my carb attached, any ideas are much appreciated!

Dutch

 

[racerone]

There is no mixture adjusting screw on those carburetors.----Post your compression numbers.-----Likely this is not a carburetor issue.

 

[oldboat1]

Och ja, Dutch. Are the air bleeds in place, properly sized and undamaged? I think I see a broken one back there -- size 30, which would be undersized anyway. Not sure.

 

[Dutch602]

Thanks for the replies, I'm pretty sure this isn't a compression issue. I have a cylinder or two drop off between half and wide open. before half throttle I always have "full" or regular power. If I can get to full speed at wide open then I have full power, it's in between cruising at 3/4 throttle that I have power issues. Been chasing this for a year now and thought I would give carb adjustment a try.

 

[oldboat1]

A year? Patient guy.

Enlarge the second photo and look for a brass piece with "30" on it. Maybe I'm seeing things.

An old fashioned but effective drop test is to hook up a timing gun so you can see it, or get a helper. At the rpm range giving you problems, see if the flashing stops (no spark).

 

[racerone]

Perhaps a set of " rebuilt " carburetors off E-bay will fix it.

 

[Dutch602]

Just to follow up: I had cracked loose and reseated the screws in each carb just to see how they looked. Went out yesterday and it ran perfectly all day. I'm not positive that it's related or that my issue is fixed but I'm hopeful.

What does the "30" mean?

 

[oldboat1]

Orifice Size 0.030 inches - 8/32 thread size.