Pre-mix oil

[Chris1882]

I just bought a 1989 150 hp Yamaha pro V that was a oil injected motor but the oil pump and injectors have been removed and they been using a pre-mix. What is the recommended pre-mix for this boat motor ?
Online it says it with the original equipment pump went from 50-1 to 100-1

[boscoe99]

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[boscoe99]

You got to pre-mix for the worst case situation. 50/1 would be it.

The motor will run at idle on 50/1. It might not run so well at WOT at 100/1.

By the way, what you read on the inner web needs to be considered carefully. Yamaha has never published data showing the various oiling ratios at varying throttle openings and engine RPM's.

Might go to a 100% synthetic oil to reduce the smoke level and any carbon build up you may get on the plugs.

[ausnoelm]

Why was the oil injection removed? If some "mechanic" told you to do so, then don't take the boat back to him, find another one that knows what he is doing.

[rodbolt17]

most likely it was removed cause the old kien pump is long long gone and the mikuni conversion kit costs a bit more than a happy meal.

the kien pumps did have some check valve failures and if they failed the common thing was to buy the mikuni kit.

there is a cheaper fix.

[zenoahphobic]

You don't premix oil. You premix the fuel with oil remember 50:1 actually means that 50 litres of mixed fuel is really 49.02 litres gasoline and 980 millilitres of oil.

Sorry I am being a smart arse.

[rodbolt17]

here in the states we call it 100 gallons of gasoline to 2 gallons of oil.

[zenoahphobic]

here in the states we call it 100 gallons of gasoline to 2 gallons of oil.

Yep, US gallons at that. But that still can create a problem if your tank can only exactly hold 100 gallons, what do you actually mix to fill this tank?