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Yamaha 70hp twp stroke

guardrail22

guardrail22

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Mayo Lake, near Roxboro NC
my 207L has a 70hp two stroke Yamaha on it, which seem to be using a bit more oil in its injections system this year. Like a quart or so every 10-15 gallons of gas. Don't recall it being this much last season.


So all you 2 cycle experts whats the norm and what needs to be checked out?
 
That's pretty strange.  Have you noticed any smoking other than on startup or have you seen any signs of oil on top of the water?

You've got a big external oil tank (in the boat) and a small oil tank mounted on the power head.  Both tanks have floats in them--one in the big tank to signal you if the oil level gets too low and the float on the power head oil tank to signal the big oil tank when to pump oil to it.  The float in the small tank also signals the pump on the big tank when to quit--when it's full. 

If there is a float problem, the pump often continues to pump oil until the small tank overflows into a tube which injects the oil beneath the carb base for burning in the engine.  That's when you see a bunch of smoke behind your boat.

Otherwise, the Yamaha 2 stroke oil injection (excluding the tanks and floats) is mechanical, and it's pretty much bulletproof and trouble free.  There may be some rubber membranes in the system that are easily changed--I forget.

Sometimes buying an engine manual is a good $25 spent.  The good ones have troubleshooting guides on subjects like oil injection.  I ran a 115 hp Yammie 2 stroke and had an oil injection problem which was fixed by replacing the electronic module receiving the signals from the floats--$241.  That was my only repair in 28 years usage.
 
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Get a 4 stroke.
 
Guardrail

Sounds like you are running around 50/1. Seems about right to me.
 
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yeah that could be, we've had a lot of tubing going on this year.


We'll be playing around until xmas so I'll just keep track of gas can fills and keep oil on hand.


Will check further when we pull it out in Dec.
 
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