The boat is kept on the trailer, and I ALWAYS flush the the motor out with freshwater per Yamaha guidelines within 10 minutes of putting it back on the trailer. I also perform a 'Salt-Away' flush to the motor a minimum of every 3rd outing. The boat is stored outside, and kept under a boat cover and under a tent.
The recent 100 hour service included the following:
- Complete water pump kit and lower unit gear lube change.
New oil filter and crankcase oil change.
4 new spark plugs.
2 new Yamaha fuel filters
1 new Racor water separating fuel filter replacement
1 new zinc anode torque tab
1 new 'anode' (not sure of the location)
1 new thermostat, gasket, and cover. (I was shocked at how corroded the original thermostat was)
1 new Yamaha remote water pressure sensor (this is an optional Yamaha factory part that failed after only 250 hours) the part was $200.
Greased all zirc fittings
Lube propshaft
Spray corrosion guard to powerhead
The total cost for parts and service was $838.
I share this with the original poster, (or anyone else who may be considering a re-power with a Yamaha F70) so as to be prepared for what I consider some very expensive ownership costs. Yes, I understand that there was a $200 Yamaha water pressure sensor part included in the bill, but this was a cost I was not prepared for.
This does not change the way I feel about the motor itself, and in the future I will be performing as many of the services listed above as I am capable.
I will say however, had I known how much the service, and cost of ownership, would be on the Yamaha F70, and had our local Evinrude dealer not gone out of business, I would taken a much stronger look at the Evinrude E-Tec 60.
In doing some very crude math, and considering the nature of how things have worn, and or have corroded on the Yamaha F70, I have reached the following conclusion. If I continue to service and care for my Yamaha F70 reasonably close to Yamaha's recommended guidelines, (and the motor lasts for the hours I think it should), I will have spent approximately twice the cost of the original purchase price of the engine itself in service costs! This may not sound like much to some people, and this may be a standard cost of outboard motor ownership. However, I also own a 1986 Boston Whaler 18 Outrage with a 115 HP Evinrude E-TEC. The service costs on that motor are much less at the dealership, and they are only every 300 hours, versus Yamaha's recommended 100 hours for the F70 4-stroke, Yes, I know, there is the cost of two stroke oil. But my Evinrude 115 E-TEC is programed for XD-100 synthetic oil (which I use very little of), and I purchase it in bulk, so the operation and service costs are still MUCH less on the Evinrude ,and for a MUCH BIGGER engine !
I am not trying to discourage anyone from purchasing a Yamaha F70 outboard, I am extremely happy with how it runs, and also how it performs on my 1988 Boston Whaler 15. I would however recommend looking into cost of ownership, and also consider the frequency at which the Yamaha F70 needs to be serviced. You may also want to take note of the distance to your closest Yamaha dealer, as you may be going there more than anticipated.
In my opinion the Yamaha F70 is a great motor, but very expensive to own considering it is only 70 horsepower. It is also a very 'advanced' motor with many moving parts and a complex electrical system, all of which require good and proper maintenance.
Hope this helps.