1995 225 V6 76degree Rebuild

[brittanydog]

I'm about finish rebuilding this motor. The orginal problem was #1 piston scored the walls. Appears to be lack of oil, before I start-up this rebuilt motor I want to try and determine the cause of the orginal failure.
My questions are:
1) There are oil injection check valve in each oil line leading to the carbs. I have the Yamaha service manual but it doesnt explain how to ensure the valve is functional. Is there a method to clean and test these check valves?
2) Or is it better to just remove these valves and run the oil line direct from the oil pump to the carb fitting with a service loop to avoid all the oil draining back to the pump? This will ensure oil in the lines for inital start-up.
3) Do oil pumps fail for just one clyinder? Is it possible to get parts to rebuild a oil pump?
4) Does Yamaha sell a oil pump block off kit? or any other type of alternative oil injection? I can pre-mix 100% of the time to ensure proper oil to the motor.

Thank You!

[boats.net]

You seldom see a oil pump failure on Yamaha motors. In most cases scored cylinders are from detonation and is fuel related problem.
The checks allow oil to flow in one direction only.
Do not remove check valves.
Yamaha has some block off plates on the "C" model engines but no others.

[brittanydog]

Oil Line Check Valves

Is there a way to clean and test oil line check valves?

[boats.net]

You can spray through them with can of carb cleaner to see flows one way only.