OX66 ticking

[Masonmobilemarine]

Not very familiar with these motors as they are a little bit weird with their O2's and all. Just haven't touched many honestly.

Working on twins today, 2000 150's. Noticed the port motor had kind of a tick to it. Wasn't a knocking sound, but more of a tick to it. It was periodic (some times sounded consistent 4 or 5 times in a row, then go away for a few seconds, come back, etc). I throttled up to about 1k RPM to see if it followed, and it did.

I listened closely and narrowed it down to cylinder #1. I unplugged the spark plug wire and dropped that cylinder and ran it again....The tick went away. Clearly it seems like theres something to that cylinder. Any ideas what I may be looking at?

I didn't do a compression check or anything like that as I was only going to be doing electrical work today, and didn't bring all my tools. Just seems odd to be that its this "tick." It sounds like a valvetrain tick, but...2 stroke.

[TownsendsFJR1300]

Wrist pin?

Not much else moving about in that one cylinder.. And it's happening ONLY when producing power..

Lower rod bearing would be more of a knock and not come and go...

[99yam40]

what about the O2 dog bone tube?
I have read they can mak some ticking noise if they do not fit tightly

[Masonmobilemarine]

Wrist pin?

Not much else moving about in that one cylinder.. And it's happening ONLY when producing power..

Lower rod bearing would be more of a knock and not come and go...

Full floating pins I'm assuming, would make sense.

[Masonmobilemarine]

what about the O2 dog bone tube?
I have read they can mak some ticking noise if they do not fit tightly

Thats what I'm thinking.

[99yam40]

I have read about fuel pumps ticking if air gets into the supply also.
make it suck only liquid fuel and it goes away

[walleye1]

O2 sensor works off of #1 cyld. Clean the tube.

[TownsendsFJR1300]

And please post back what the issue was (if found)…

Can you post the exact model #?


Just want to look up the parts Fisch and see where the o2 sensor and "dog bone" is...

[Masonmobilemarine]

O2 sensor works off of #1 cyld. Clean the tube.

That makes perfect sense then.

Won't be able to tell you results, customer didn't want to do anything...just worry when it "becomes an issue."

I advised against it, sense if O2 is reading wrong/not working properly...it could run lean. Not sure if that means no oil, but just figured it wasn't wise. Wish I knew these motors better.

It was an Sx150txry.

[Jeff_H]

My servicing dealer told me ticking is usually a sign of the O2 sensor not functioning properly. My 2000 150HP OX66 has had that ticking sound on and off for the past number of years. Late last summer I noticed it was running rough, and took it in for service this past March (Minnesota, short boating season). The dealer called the next day to confirm it was indeed running rough. He said the O2 sensor was shot. As this was the first time it had been serviced or replaced, I thought 19 years of service was pretty good. He said the main reason it lasted 19 years was due to the additives I use religiously - Starbrite Startron and Yamaha Ring Free Plus.

I'll tell you I've never heard it run smoother that it did out of storage this spring. And, no more ticking. My servicing dealer suggested I have the O2 sensor pulled and cleaned every other year.