70HP 2 Stroke - Smoking Issues

[Tantalus]

Hi, we have a 1999 70hp injected 2 stroke. She runs absolutely fine under power and starts well. When cold and at idle she excessively smokes and eventually goes away and smokes like a typical 2 stroke. If we shut down for around 1/2 hour and start up again, excessive smoke again. Where am I best to start diagnosing?
We have just bought it and am unaware of the oil type previous owner was running, so planning to drain oil and start with Yamalube, is this the best to use?
I have read that there are two 'O' rings at the back of the oil pump which could be the issue also, so that could be next. How easy is it to get to these?
What are the most common problem areas that I should look at? Any suggestions would be greatly appreciated.
Thanks.

[robert graham]

I understand that if the auto-lube pump has a problem then the oiling system will " default" to a wide open setting.....I don't know first hand about this since my C90 is a premix motor, but your problem sounds sorta like a wide open oiling pump/system....just an idea...

[Jason2tpa]

Bearing in mind “excessive” smoke is subjective, smoking after cold starting an older 2 stroke is expected. After warm up it should dramatically decrease. The oil pump is mechanical, so there isn’t an adjustment to be made that can increase/decrease oil output. But the rod connecting the pump to carbs needs to be adjusted to spec.

[Tantalus]

Thank you, where can I find that exact spec? It makes a lot of sense. Yesterday I found the plastic joint link broken which the end of the rod screws into and the nut adjusts accordingly. I have ordered a new one. What is the spec when connecting it up again? I am presuming it has been wide open as Robert suggests also.

[panasonic]

Can you post the engine model and serial number on the data plate on the transom bracket. I or someone else may have the service manual for your engine...look it up for you.

[Tantalus]

Looks like the model number has been slightly peeled off. All I can read is ‘70BETO’ and can also read ‘L’ and 4946. Hope that helps.

[panasonic]

Here is what I see. Manual is for 50,60,70,90hp

Look at page 4 for your model and you will find oil pump tests and rigging in section 3. I would suggest you do the oil pump operational test to see if it puts out the proper amount of oil.

As you can not supply the exact engine identification, use this manual at your own risk. Pretty sure it is the proper manual for your engine though.

Good luck

https://www.manualslib.com/manual/10...0g.html#manual