2004 Yamaha 15hp 4 stroke possible lean condition and overheating

[Bangstick310]

I’m running hot, plugs show both lean condition and overheating condition if that makes sense, . I don’t know what’s causing it, I Rebuilt carb, new water pump, thermostat, new plugs, new oil,

I should note I didn’t touch the air/fuel mixture screw because there is what I believe a plug in front of it and I can’t remove. I’m guessing I should drill out? Try to pull and clean?

few questions can a bad oil pump cause overheating and result in showing a lean condition on spark plugs cause of high temps?

I thought maybe a water issue but pulled the heads and water system is clear. No obstruction.

Any help on where to start to diagnose I would appreciate .

[boscoe99]

Carbureted Yams are known to run lean. Thanks to the EPA.

Have you tried turning the idle mixture screw out a tad or two to try and make the fuel mixture a bit richer?

[99yam40]

well how do you know the motor is running hot?
you cannot clean a carb properly without taking it completely apart to clean all passages and jets.
yes the pilot screws need to come out

[Bangstick310]

Carbureted Yams are known to run lean. Thanks to the EPA.

Have you tried turning the idle mixture screw out a tad or two to try and make the fuel mixture a bit richer?

There was a plug in front and I was hesitant to try and get it out. Do I drill the plug out. ?

[Bangstick310]

well how do you know the motor is running hot?
you cannot clean a carb properly without taking it completely apart to clean all passages and jets.
yes the pilot screws need to come out

I did everything except pilot screw becuase of the plug in front. I’m assuming I have to drill it out to get access?

also I can send pics of plugs when I get home later tonight. Plus I put a temp gauge around the plug area when running and if I remember correctly it was in the low 200 degrees and climbing before I shut it off.

[99yam40]

yes, if the head is getting close to boiling temp, then you have a water circulation problem.
you just have to figure out where that problem is.
when does it overheat?
does it set an alarm or bring in RPM limitation?

[boscoe99]

The plug is drilled out. Taking care not to insert the drill bit too far and damage the screw. Then screw a screw into the just drilled hole. Yank the plug out by pulling on the screw with a pair of pliers.