1990 yamaha 200etxd 6 cylinder 2 stroke, lower port cylinder has oil buildup

[Alex60020]

I'm a bit stumped with this one, engine was running without any issues after it was started. Starting was a bit of a challenge, had to have another person pull the choke in and out on the motor while starting. After the motor was hot and running would start with no issues.
About 2 weeks ago the engine started acting up, when on the water running at about 2-3k rpm, after giving more throttle, it would stay at same rpm's then it would kick up the rpm's about 20 seconds later.
I pulled the plugs and lower port cylinder plug had oil build up all over it(all other 5 plugs looked good). I pulled the head and there was about 1/8" of oil buildup in that cylinder head.
This boat has 2 engines and this engine has been using about 30% more oil then the other.


Any ideas on what could be causing this?

Thanks in advance for any help
Alex

 

[robert graham]

I believe there was a thread regarding this that mentioned the oiling system having some type of fail-safe feature where the oil would pump maximum in case of a system malfunction....hopefully one of the other guys will recall this and chime in....