Overheat (poppit valve)

[seasick]

The plugs only have about 5 minutes on them this season in the picture, not sure of that makes a difference or if they would have burned clean already (fogged and sea foamed end of the season). Plugs were replaced last season and gapped (will recheck when I pull them after putting some hours on it Sunday).
It is a 1996 s150txru. I felt she was smoking more at the end of last season but think it was just the cold and humid mornings (but did she tend to blow a little smoke on startup which lends to your running rich theory) but At the dock the other day she didnt smoke really all. Running Ngk plugs (same kind as inside the cowling says and same as previous owner used). I did check the oil linkage and all looked fine, decided not to mess with it as rich is safe.

If motor was fogged last season and the plugs were replaced BEFORE the motor was started this year, the plugs may get fouled. I always start and run the motor on the old plugs in the spring and then change the plugs. Regardless, take a look at the oil pump linkage adjustment.
That motor will smoke more in cold weather and humid weather. The smoke would be white. If blue, it mat have too much oil in the mix and if black, the gas mixture may be too rich.
My 150 is a 2000 and at times it does smoke a lot ( forget about first firing after the winter, I don't even count that!).
The original plus are NKG but the actual part number is what you need to confirm. My motor calls for BR7HS-10 but I think that the new plugs available today have a different number. I am still working on existing stock

 

[imjus4u2nv]

If motor was fogged last season and the plugs were replaced BEFORE the motor was started this year, the plugs may get fouled. I always start and run the motor on the old plugs in the spring and then change the plugs. Regardless, take a look at the oil pump linkage adjustment.
That motor will smoke more in cold weather and humid weather. The smoke would be white. If blue, it mat have too much oil in the mix and if black, the gas mixture may be too rich.
My 150 is a 2000 and at times it does smoke a lot ( forget about first firing after the winter, I don't even count that!).
The original plus are NKG but the actual part number is what you need to confirm. My motor calls for BR7HS-10 but I think that the new plugs available today have a different number. I am still working on existing stock

I am running the same plugs br7hs 10, they haven't been changed this year (I used to swap out ever year in my old boat but seemed like a waste. Pretty sure i have an extra set I will swap them out after I run on Sunday if any issues). Willl observe for smoke also.

 

[Bloodweiser]

might want to run it in a tub with some vinegar to work out salt deposits. you'd be amazed how much is in the motor. agree on the tstats. I change em every 3 years. never had an issue.

what is the ratio of vinegar to water for this to be effective? and how long do you have to run the motor.

 

[seasick]

I am running the same plugs br7hs 10, they haven't been changed this year (I used to swap out ever year in my old boat but seemed like a waste. Pretty sure i have an extra set I will swap them out after I run on Sunday if any issues). Willl observe for smoke also.

That's the correct plug. I find that my plugs can last 3 seasons. I don't run a lot of hours though. That said, if the old plugs are getting fouled and/or sooted up, so will the new ones (assuming the old ones are firing. I think you would know if they weren't) Run the old for a while or all season and then have a look but.....check that oil linkage
If you keep pretty accurate records of how much gas and oil you add, over time you can get an estimate of the oil ratio. If you put a lot of hours and therefore use more gas and oil, at the end of the season (or in between) you can see what your average ratio is. That motor runs about 100 to 1 at low throttle and up to about 40 to 1 at high revs. The ratio is totally a function of throttle opening and not load, ecu, sensors etc.
There is a really accurate method to measure the oil output rate but it is a pain in the neck to do and it requires a portable tank with premixed gas and oil)
I do take a look at the end of a season to see if something seems way off.
Unfortunately, it's a lot more obvious when too much oil is being used than it is to detect not enough (other than the KABOOM case)

 

[leeccoll]

what is the ratio of vinegar to water for this to be effective? and how long do you have to run the motor.

I put in 10 gallons in a 100 gallon trough. add a squirt of dishwashing liquid soap.
Run the engine for 45 minutes in neutral. The deposits I had dissolved in the tub after about 20-25 minutes.
I also varied the engine rpms at times up to 2500 max.

 

[Bloodweiser]

Thanks Lee

 

[imjus4u2nv]

Thanks guys - boat ran mint.

 

[leeccoll]

That's good news.

 

[Boxster964]

Its crazy but I just dealt with the same over heat condition on my Yamahas. Mine are 2 stroke 250 OX66 with maybe 150hrs and they were over heating at idle with brand new water pumps. I found the pop it valve was sticking however there is a new style pop it valve. The new poop valve has a rounded head and not Cross area on one end so it will not stick in the block. Real cheap fix for a change. Sorry I did not take pictures but the difference is easy to see. Also do not forget these I believe all Yamahas have enging water jacket anodes. That was 1 season of wear. 2 in each engine

 

[imjus4u2nv]

Its crazy but I just dealt with the same over heat condition on my Yamahas. Mine are 2 stroke 250 OX66 with maybe 150hrs and they were over heating at idle with brand new water pumps. I found the pop it valve was sticking however there is a new style pop it valve. The new poop valve has a rounded head and not Cross area on one end so it will not stick in the block. Real cheap fix for a change. Sorry I did not take pictures but the difference is easy to see. Also do not forget these I believe all Yamahas have enging water jacket anodes. That was 1 season of wear. 2 in each engine

Thanks for the info - had no clue there were anodes like that. Having a hard time finding on my s150txru, where are they located?
I found two small anodes but not sure how to get to these.