O2 Sensor Question

[MYRX]

I took my O2 Sensor out this was weekend to clean it, (following instructions posted on this link). My motor is a 1999 OX66 225. When I removed the barbell piece, there was no O-ring or metal O ring as described in the "how to fix it link" on this site. Also, when looking at the parts diagram from SIMYamaha, these two items are not listed either. I bought new gaskets, cleaned everything and I am ready to re-assemble. I just wanted someone to confirm that these two O-rings are not used on this year motor and HP. If they are supposed to be there, someone please give me the part numbers so I can order them.

I might add, I had very little carbon build up and my motor was last tuned up 2.5 years ago. At that time the mechanic told me I had a lot of carbon build-up. 2.5 years ago I changed plugs to an 8 from a 9 and changed oil from Yamalube. I now use Pen. Seems like it made a difference. For the record, I use the boat at least 38 weekends a year.

[RL552]

I've got a 01 ox66 225 and there's no O-rings on mine. Some have them and some don't, I'm curious if they saw a need and what was it, for the O-rings that were added to the ones that have them.

[yam911]

I've got a 01 ox66 225 and there's no O-rings on mine. Some have them and some don't, I'm curious if they saw a need and what was it, for the O-rings that were added to the ones that have them.

Yamaha must have seen a need or would not have made the change. Unfortunately, the engineers in Japan often don't tell the world why they do what they do.

My best guess what that Yam felt there was a need for improved sealing between the O2 sensor holder and the block. Just a guess however.

[MYRX]

Many thanks, picture shows exactly how my 1999 looks. Already back together and running fine.