I own a Yamaha 150 HP 4-stroke. By mistake, I added a gallon of Yamalube when filling my tank (1:55 mix) (something I do for my older 2-stroke engine). Is this a problem?

SOURCE: do i have to mix 2 stroke oil on the gas for the 4

DO NOT mix oil in the gas on your four stroke engine. You will foul the spark plug(s), build up deposits on the valves and head, and make a smokey, smelly mess. A two stroke engine uses the fuel/oil mix to lubricate the engine before being used as fuel. A four stroke engine has a separate lubrication system and does not normally burn any oil. As the name implies, a two stroke engine works in two strokes. The first stroke is downward, where the fuel/oil mix and air are drawn into the cylinder. The momentum from the crankshaft counterbalance or force from the other cylinder(s) drive the piston back up compressing the mix, and the spark plug sparks at or slightly before the top of the stroke. The rapid combustion of the fuel/oil/air mix drives the piston down, which is the power stroke, and then the cycle starts all over again. A four stroke engine has an intake stroke down taking in the fuel/air mix, a compression stroke up, a power stroke down as the fuel/air mix is ignited at or before the top of the stroke, and a exhaust stroke up before starting all over again. A four stroke is much cleaner and more reliable than a two stroke, but it is heavier and has less torque. A two stroke engine is much lighter and has more torque, but takes more maintenance.

SOURCE: smoking outboard

Sounds like your running a bit rich. Try leaning down your air/fuel ratio.

SOURCE: yamaha outboard 150 4 stroke bad vibration at 700

is you propeller bent? a dent the size of a quarter will cause a shake. If not that means your engine is misfiring. here are the troubleshooting test and tool list you need to find out. Tools(1) A compression gauge (2) a spark gap tester.(3) A Clymer service manual for your engine. (you can purchase from your local outboard dealer. I know all these are expensive but if your going to be a outboard tech you will always need them. Troubleshooting (1) check compression. without the year model I'm giving you a average numbers. Look at your Clymer manual. all cylinders need to be over 100 lbs and equal each other within 5 lbs.(2) check spark. use a spark gap tester all cylinders should jump a half inch gap. if you have good compression and good spark, fuel is the problem nine times out of ten.Ethanol gas is proven to stay stable in fuel systems for 30 days in 90 + degree heat. Drain gas tank,clean fuel lines replace primer bulb and replace all fuel filters. Yamaha has a gravity filter under engine coul clean it. Finally replace spark plugs, I know spark plugs probably don't look bad but this is a outboard. Fresh spark plugs means less resistance for the ignition system. The ignition system is week compared to automotive. Test drive boat, if the problem is still there then there is further steps to take. Again I don't know the year model so I guessing its fuel injected. Pull out your clymer manual. what is great about the Clymer Manual for Novice techs is it gives detailed info on your outboard. Troubleshooting tips and teaches you how your outboard works.

SOURCE: ktm 50cc 2 stroke selfmixer can i jus mix oil gas

Yes. If you look around, you might be able to get a kit to eliminate the oil injection pump.

Testimonial: "cheers m8"

SOURCE: i'm wondering if my 2003 yamaha TTR 125 is a 2

Hi and welcome to FixYa,

It uses a 4-stroke engine.

Good luck and thank you for asking FixYa.