115 4 stroke Yamaha, please reply

[Scallop]

I may have asked a former un-ansawered question inproperly, if any one operating a 115 4 stroke yamaha for a while can tell me about the engine performance I would be thankful? I read about making oil and don't like the sounds of a new engine doing odd things like that?

[robert graham]

Do a thread search for "making oil" for a good bit of information regarding this subject. Some of the 4 stroke motors have a blow-by issue that puts gas into the crankcase area creating an over-full situation. Having the correct prop to allow for maximum RPM's at WOT and running motor some at full throttle at least some of the time are important for this. Good Luck!

[Scallop]

Why is it that 4 stroke cars engines do not have this problem of making oil, they are never run wide open and have a transmision that keeps rpm down, maybe the transmisions keep the proper load om the engine, unlike a prop, unless it is a variable prop?

[robert graham]

I don't know why, other than in an automobile engines the pistons travel in a more or less vertical direction and most of the outboard pistons run in a horizontal direction, but maybe some other reason? My VW rail buggy has a "boxer" engine and it doesn't make oil. It's a good question for some of the experts on here.

[Aleutianwest]

making oil

If the thermostats get glogged open the motor will not get up to temp and not burn fuel correctly
and earlier models had a bad seal design in oil pumps and had water get in the oil basin hope that helps

[Scallop]

yes this does help, certainly this is a big difference from a car where we tend to know at all times if the car is driving at normal engine temps. When replacing thermostats in other outboards I have often wondered if they had been stuck open, just by the way they look.