2 Stroke Oil Mix

[Cheechako]

Originally Posted by tangara

You are taking of Yamaha engine the older models were 50 to 1 and the new models are 100 to 1 i don't believe these change were made whit-out intensive test. Excess of oil create carbon build up on piston seal ring.

IIRC my '94 Yam 15 was 100:1

[gonesail]

2 strokes always run a bit messy and the plugs will look like that. Use the best oil you can buy and mix to specs. mine runs with 50:1.

[rbk]

Other thing to consider is the original owner said 50:1 but I know a lot of guys who think they’re mixing 50:1 by eyeballing ‘about right’ and not doing the math, and they’re mixing richer, then unsure of their mix add a bit more for good measure. I bet if you mix a proper 50:1 change the plugs and run it good you’ll find it’s just fine.

[a64pilot]

We bought a 2010 Prius new, when we bought it the oil change interval was 5,000 miles, a couple of years later after much pressure from environmental groups it was changed to 10,000 miles, reason given was the car was built as a low impact to the environment car and a 10,000 mile oil change interval would reduce that impact.

Now does anyone really think the car won’t have a shorter lifespan with half as many oil changes?

It’s the same I believe with 100 to 1 oil, of course it will work, it will certainly last until after the warranty period is over, but will it last as long as it would with 50 to 1 oil?
I don’t think so, but then I’m also sold on four strokes, particularly fuel injected ones.

[LAGO]

Your photo of the spark plug hole looks a little bit oily. Was the plug thread and insulator also a bit oily? 'Cos if the insulator is dirty/oily it can cause a weak spark. Even fingerprint oil. Maybe the plug was not in tight enough? But it only needs hand tight and a quarter turn. Or maybe the plug gasket has been over compressed. But the plug doesn't look too oily to me - for a 2 stroke!

[UFO]

Originally Posted by Pete7

Just before the engine was shut down for the last time before the plugs came out, was it being run slowly or idling for any length of time which might have caused it to oil up?

Pete

Yes - A large % of time it has been run at low revs - Mainly around a local Marina where we are stuck or to and from an anchorage when we are out on a local island (short distance)

[UFO]

Originally Posted by Vasco

When the old 2 strokes were allowed in Canada Yamaha would call for a 100:1 mix in Canada. Buy the same engine in the Bahamas and it called for a 50:1 mix. I heard that the only reason they went to 100:1 was because of EPA rules. To the OP, are you running the right plugs? I always use NGK BR7HS-10. As to 2 stroke oil I always use TC-W3. And I always run them with 50:1 mix.

It has the 8H-9's (from Memory) I have though already purchased the BR7HS-10s - Hopefully this will help.

[ggray]

I use Amsoil 100:1 oil mixed about 80:1, or little thinner.

WRT VRO and oil mix required at slow speeds, an outboard mechanic I had a great deal of respect for stated that the lubricating quality of straight gasoline was nearly sufficient by itself for a two stroke motor at idle. Most of the oil in excess of that just fouls the plugs, etc.

[CF32907]

CaptVR here,
First, you should have an owners / service manual for your engine, but putting that aside why would you guess, or ask on a forum. A simple matter to call your Yami, dealer. Give him your model and S/N, and he will tell you exactly what you should be using / mixing. No guessing involved.
Capt. Vince Rakstis, Ret. MS
If you don't have a model / S/N plate on the engine, it probably was stolen along the line somewhere....

[Vasco]

Originally Posted by CF32907

CaptVR here,
First, you should have an owners / service manual for your engine, but putting that aside why would you guess, or ask on a forum. A simple matter to call your Yami, dealer. Give him your model and S/N, and he will tell you exactly what you should be using / mixing. No guessing involved.
Capt. Vince Rakstis, Ret. MS
If you don't have a model / S/N plate on the engine, it probably was stolen along the line somewhere....

See post#12. Can't rely on the dealer. Yamaha will tell you 2 different things depending on what country you're in. For example in US and Canada 100:1 in Bahamas and many other countries 50:1. Same engine, different mix recommendations.

[Calaban-Alleria]

My experience from 2-stroke motorcycles from "days gone bye" would suggest you stick with 50:1 with the best quality oil. Oil and plugs are much cheaper than engine rebuilds. If you tend to run your outboard mostly at low revs then investigate going to a hotter plug. From the picture it does not look too bad. Note: to do a proper plug reading you need to hold the motor at a constant speed-load for a period of time then kill the ignition, pull the plug to check colour. If you close the throttle you wont get a accurate picture.

[topcar]

I have a heap of experience using high performance two-stroke engines in racing karts and motorcycles. I mix at 40:1. have a maxim..."Oil is cheap— pistons are expensive. Choose one!" I use NGK BP6HS plugs. These have a projected nose which burns cleaner and are one range hotter than the standard #7. My plugs have the nice chocolate colour... no sign of running too hot. These are water-cooled engines after all, so extreme high temperatures should not be an issue. Use 95 octane unleaded fuel... it seems to have additives that burn cleaner. Stay well clear of ethanol fuels. A trick from the racing days... carefully file/grind off a couple of mm from the end of the earth electrode so that it only covers half of the centre electrode... helps to avoid fouling. Gap it at 25thou. Use a good quality modern synthetic two-stroke oil. Good luck.

[Davo1404]

Do not run it at 100 to 1. Risk of seizing. My 2019 Tohatsu 9.8 states 50 to 1.Your plugs Wil look like this if you were idling for a while. I would check the hand book for the plug type. Maybe they are to cold?

[BugzyCan]

I have to agree with RBK and his suggestion about mixing it wrong from the start. You know you have too much oil in it when you start it and an oil slick appears behind the boat.

Figuring out 50/1 is really simple using liters. It goes like this

50 liters of gas you add 1 liter of oil. The easy way to figure it out, is to take the amount of gas used to fill the tank, double it, and add a zero.

So if you buy 13 liters of gas, it equals 26 and add a zero you get 260 ml of oil to add. You can prove this is correct by taking 50 liters of gas, doubling it to 100 and adding a zero, this then is 1000 ml, or 1 liter. Simple.

Not sure how that all works with US gallons.