Surething
03-07-2005, 10:01 AM
I have a 21 ft open boat and it has a 200 yamaha 066 with a pump. what do you all think I should get for fuel econ. and how much oil should it use. I traveled about 25 miles the other day and it used about 25 gal of gas and about 1 gal of oil.
Your MPG really depends on your RPM's.
I have Yamaha twin 200's with props on my boat. Running with both engines at 4100 RPM I get about 1 mpg TOTAL (or maybe a little better). Obviously you sacrifice economy with a pump, but most tally's I see show your engine getting about 3.5-3.9 mpg with a prop. If you're not getting 2 mpg something is odd.
For 25 miles, on both engines I would only expect to consume about 1/2 to 2/3 of a gallon of oil TOTAL.
Now, if I crank the boat up to 5200 RPM's, I'm not sure what my mpg goes to (I will shortly as I am just finishing up getting my flowmeter in), but I know my oil usage goes WAY up. At that level I would burn between 1-11/2 gallons of oil TOTAL.
1 gallon of oil is a lot for your usage. 50:1 is standard if you mix it with your gas, and that would put you at 1/2 gallon oil for 25 gallons fuel. With Yamaha oil injection, the oil usage typically goes way down since it is a mix on demand situation. The fuel-oil ratio ranges between 200:1 at idle up to 50:1 at WOT. If you are getting too much oil, this will also hurt your fuel economy.
So, what RPM's do you typically run at?
goodkarma
03-07-2005, 04:11 PM
I have that same set up with the jet and get terrible mileage. I've never really kept track but I bet it's close to what you outlined.