So I've been fouling spark plugs, my oil smells like gas and I cant figure out the issue... I noticed cylinder 4 5 6 run way richer than 1 2 3 and I turn the fuel down a bit (both run rich) fouling all 6 after about 20 mins of idle I sand blast the plugs and repeat 2 more times and decide to change the oil and no good. I know the carbs are a bit old so I was on my other su carbs that are I'm a lot better shape and now its flipped cylinder 1 2 3 are running super rich and 4 5 6 super lean so I turn down the fuel on the one carb and repeat multiple times but no matter what within minutes they foul it's like the fuel isn't going down at all when I use the fuel adjuster nut... any ideas? 

Also sorry I've never really worked on su carbs only done what I've read online, so if this sounds kind of dumb my apologies.

I bought a motor that had half fuel half oil too. The head was nice and shiney under the valve cover.

Had to rebuild the carbs. Did your's just start doing this? Something is out of adjustment. If not consider rebuilding.

Just thought about something to check. Make sure your nozzles are moving up and down with the choke lever. They could be stuck in the down position. Your choke wires could be loose or out of whack. The flat linkage bar could be bent. The small hoses could be wrong and hardened preventing them from movement. A lot of "could be" on those SUs. 

Edited August 26, 20195 yr by siteunseen

Disconnect choke cables and push Nozzle (7) in figure below, up from the bottom. They are probably stuck down.

The outside of the brass nozzle's tube usually gets gummy and dirty over time and binds in the Nozzle Sleeve(1)

 

You can remove the Nozzle and clean with carb cleaner and a scotchbrite pad but watch out for the screw and washers holding it to the lift arm (shown below):

w

 

Edited August 26, 20195 yr by 240260280

I agree with Site and Blue. You can reach under the carbs and push up on the nozzle. You’ll feel it snap back.  If it is hanging up, it’ll cause very erratic idle and will blacken your plugs on those three cylinders. You’ll have to do this every time you choke the engine. Those nozzles are famous for binding when linkages aren’t aligned perfectly.

 

5 hours ago, siteunseen said:

I bought a motor that had half fuel half oil too. The head was nice and shiney under the valve cover.

Had to rebuild the carbs. Did your's just start doing this? Something is out of adjustment. If not consider rebuilding.

Just thought about something to check. Make sure your nozzles are moving up and down with the choke lever. They could be stuck in the down position. Your choke wires could be loose or out of whack. The flat linkage bar could be bent. The small hoses could be wrong and hardened preventing them from movement. A lot of "could be" on those SUs. 

 

2 hours ago, 240260280 said:

Disconnect choke cables and push Nozzle (7) in figure below, up from the bottom. They are probably stuck down.

The outside of the brass nozzle's tube usually gets gummy and dirty over time and binds in the Nozzle Sleeve(1)

 

You can remove the Nozzle and clean with carb cleaner and a scotchbrite pad but watch out for the screw and washers holding it to the lift arm (not shown below):

w

 

 

1 hour ago, Diseazd said:

I agree with Site and Blue. You can reach under the carbs and push up on the nozzle. You’ll feel it snap back.  If it is hanging up, it’ll cause very erratic idle and will blacken your plugs on those three cylinders. You’ll have to do this every time you choke the engine. Those nozzles are famous for binding when linkages aren’t aligned perfectly.

 

Alright I'll try 240260 suggestions first and if that doesnt work I'll probably just look into a rebuild kit, I just recently picked up this 240 but it didnt happen until after I took it for a drive, after that all hell broke loose lol! After work I'll get on it, thanks guys!

BTW....You don’t have to disconnect the choke cables to pop up the nozzle......literally a 3 minute fix if that’s the problem and it sounds like it is. Just stick your hand under each carb and push up the nozzle....you’ll feel it pop up if that’s the problem.

I'm going to change my username to Tree Shaker. 

4 hours ago, Diseazd said:

BTW....You don’t have to disconnect the choke cables to pop up the nozzle......literally a 3 minute fix if that’s the problem and it sounds like it is. Just stick your hand under each carb and push up the nozzle....you’ll feel it pop up if that’s the problem.

 Perfect I'll get back to you guys in awhile letting you know what's up! (Like 6 hours from now) thanks again everyone!

9 hours ago, Diseazd said:

BTW....You don’t have to disconnect the choke cables to pop up the nozzle......literally a 3 minute fix if that’s the problem and it sounds like it is. Just stick your hand under each carb and push up the nozzle....you’ll feel it pop up if that’s the problem.

The front carb has a pop to it and the rear carb doesnt, but the front 3 cylinders are the ones running super lean? I pulled the nozzles and will post a pic of them, I noticed the rear carb needle sits a but lower than the front needle?