70 hp yamaha wont idle correctly, no power off idle when load tested, etc...

[Carmstrong]

1989 70 hp yamaha wont idle correctly, no power off idle when load tested, etc...
Just bought used that's been sitting in storage for a couple of years

Compression seems to be ok 120
took the carbs off and cleaned along with clean fuel & additives
the jets in the carbs were contaminated to the point where I needed to probe a wire through to get them to open up
plus the middle carb had some black looking substance in it
took the fuel pump off and apart it looks to be ok
balance & load tested at the ramp
It does idle but doesn't seem correct when I try to adjust the mixture screws
plus off idle, & under a load the top cylinder is the only one that really seems responsive

Was researching some of the other forums for tips
that suggested that the inlet side of the carbs, jets, etc... can get to the point of not being able to restore with typical means?
Do I need to replace the jets
or carbs
Didn't do a cylinder leak down or vacuum test yet
any tips, suggestions, specific technical info would greatly be apperiated

Thanks for the help

 

[bloodylongair]

Re: 70 hp yamaha wont idle correctly, no power off idle when load tested, etc...

Did u have fuel leaking from the carbs as well? Did u end up replacing the jets? My 2stroke 70hp yamaha leaks badly and looks like I'll have to pull it all apart and c where the leak is.