1995 200hp Variable oil ratios.

[MakoJohn]

I have two 1995 200hp 76 degree V6s with carbs. The orginal precision blend oil system was removed by a previous owner and I have been putting oil in the fuel tank at a ratio of 50:1.

Problem is the engines smoke heavily at idle and a bit on the twenty minute 5kn cruise to get out of the canals and I would like to reduce the smoke.

I heard that the precision blend system varies the oil added from 150:1 at idle to 50:1 at WOT? Does anyone know what these ratios are?

If I don't take my engines over 4000rpm am I safe running an oil mix of say 100:1?

Thanks.

[bajakeith]

Omg !!

50 TO 1..... Only run at 50/1... Grrr !

[ausnoelm]

Get the oil system working, use quality oil, go boating and enjoy......

[MakoJohn]

Mate you must be an early riser. No chance of getting the oil system working here in Venezuela.

Get the oil system working, use quality oil, go boating and enjoy......

[MakoJohn]

The Yamaha precision blend system doesn't just run 50:1 so if I don't go past 4000rpm there must be other options.

50 TO 1..... Only run at 50/1... Grrr !

[boscoe99]

If smoke is the concern I would try something semi synthetic in a different brand.

[ausnoelm]

Don't try to convince yourself anything less than 50:1 will be OK, pre mix is 50:1 end of story, but it's your motor, mix what you like, you asked for help, you got help, but don't like the answers.

[MakoJohn]

Thanks will look into that, my choices maybe limited here in a rapidly self destructing Venezuela.

If smoke is the concern I would try something semi synthetic in a different brand.

[MakoJohn]

Mate keep your pants on, I appreciate all the answers I got.

Still would like to know what the Yamaha precision blend system ratios are though.

Don't try to convince yourself anything less than 50:1 will be OK, pre mix is 50:1 end of story, but it's your motor, mix what you like, you asked for help, you got help, but don't like the answers.

[rodbolt17]

the numbers your looking for are not published.

from observation it actually comes out to something like 130/1 down to 40/1 depending on throttle angle and engine speed.

man I wish I was in Rio Chico or El manteco .

just run it at 50/1 and pray maduro and crowd leave while anything is left.

[MakoJohn]

Thanks for the info.

Maduro won't leave without a fight, he has no where to go. I'm not Venezuelan but I do feel really sorry for the locals. Hope it all works out without blood being spilt. Interesting year ahead...

the numbers your looking for are not published.

from observation it actually comes out to something like 130/1 down to 40/1 depending on throttle angle and engine speed.

man I wish I was in Rio Chico or El manteco .

just run it at 50/1 and pray maduro and crowd leave while anything is left.

[zenoahphobic]

I thought the leanest oil mixture was about 100:1 and the richest 50:1 but as advised no official value but I guess individuals have measured it although I don't know how you would actually measure this; requiring laboratory setting.

The advice would be use the best quality oil, semi if you have to, if your criterion is to reduce the smoke at lower RPMs.

50:1 is arbitrary but I would not use less, unless I could actually limit the max RPM.

Ofcourse you could always fix or attach the original injection, that was primarily designed to enable the engine to use less oil or unnecessary oil.

[boscoe99]

Now that I think about it some more, the oil ratio is not a function of engine RPM, it is a function of throttle position opening.

The oil pump provides more or less oil as the throttle opens and closes. It cares not a wit about engine RPM.

Live with the smoke. It is what two stroke pre mix motors do. Or live with the new motors that will be purchased to replace the two old motors that will fail due to lack of oil.

[zenoahphobic]

I don't know if you have seen the Australian film "The Castle".
Where Kearigan whilst out in his boat not another sole in sight famously says: " love the serenity and the smell of two stroke!"

[MakoJohn]

Thanks Boscoe and Zano. I pick upped the part in Rodbolts response about throttle angle. I will stick to 50:1 but look into a different oil as Boscoe suggested. I've cut the smoke in half by running on one engine in and out of the canals and whilst *****ing.

2 engine at 1400 rpm gets 7kn
1 engine at 1700 rpm gets 7kn

So another question, do I need to raise the engine I'm not using at these slow speeds?

Thanks for all the responses.