Yamaha 250 OX66, Smokey!!

[BOATINO1]

Hey Guys,

New to this forum but have posted some info on The Hull Truth and someone recommended here so here I am. I have twin 2000, 250 HP Yamaha Ox66 on my boat. This year they seem to be smoking a bit more than before. They smoke continuously at idle. They do not hesitate and run up to 5600 rpm at full throttle. They have about 950 hrs. on them. I have recently decarbed both motors, tried full synthetic Penzoil, and recently replaced the Oxygen Sensors. I have used ring free religiously, but this is the first year I tried the penzoil full synthetic over Yamalube 2m. It did not help at all. Any other suggestions as I don't really trust the yamaha dealers in my area very much. They seem to only want to work on 4 strokes. I'll try to attach a short video I took of them running at the dock.

https://www.youtube.com/watch?v=Nw6qJP3Iurk


Thanks in advance for the help.

John.

[nickmo12]

There's a rod that goes from the throttle plate to the oil pump. At the oil pump it is fastened with a plastic connector. They quite often break or strip out. While you are at that rod, adjust as per the manual.

[nickmo12]

Watched your video after the last post. The connectors look good, but they still may need adjustment.

[BOATINO1]

I had looked at the oil rods again when I did the oxygen sensors. I think the manual called out .040" and it seems like it's right. The video doesn't show it that well. I do about 50 hours of slow salmon *****ing with these motors 700-1000 rpms per season. Is there anything else I can do before I get the dealer involved. Anything else that would cause that smoking? Both motors smoke at about the same rate, that's why I thought it would be odd that the oil arms would be out of spec. Low pressure fuel pumps were changed out 2 years ago, spark plugs are 25 hours old, vst filter changed 2 years ago. I'm running out of ideas.

John

[rodbolt17]

my guess would be a combination of stuff.
also most the 3.1L motors had to have about 5 treads cut off the oil link rod to PROPERLY adjust the lever arm to stopper clearance.
you MUST either unclip the bottom two throttle shutters OR do the correct link and sync procedures.
but it CANNOT be done by just setting it to the idle position.

[TexasSkeeter]

I have an OX66 that smoked crazy. Replaced the rubber Oring between the oil pump and the block and it solved it. You might try that

[TexasSkeeter]

Check out items 2 and 19 here:

2001 VX225TLRZ Yamaha Outboard OIL PUMP Diagram and Parts