Oil ratio

[Dave Strong]

Or use the metric system of measurement and it becomes idiot proof as well.

Just about the only thing the metric system has going for it, if you had to convert from normal. Still have trouble relating metric to standard sometimes.

Dave

[ozziffied]

Then, spend $4-5 on an oil-to-gas ratio bottle with all the different ratios printed out on the side, and voila!!!...Correct oil ratio becomes idiot proof.

I boat 3 or 4 times a week.... This works great for me!

[DanielC]

1 gallon is 128 fluid oz.
Divide 125 by 50, you get 2.56, so a little over 2 1/2 os of oil in a gallon = 50 to 1
128 by 40, 3.2 oz of oil, = 40 to 1
128 by 32, 4 oz of oil, = 32 to 1.

When i was running a premix boat, 1970 Merc 135 in line, I used a baby bottle.
I went with 3 oz per gallon, to kept the math simple. The ratio was 42.667 to one.

[Jay Smith]

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I use the bore size and stress levels to determine the oil ratio.
2.4 and 2.0 liters that are recreational turning less than 8000 I use 50:1 ( more than 8000 I use 40:1 )
ANY 3.500" bore ( 2.5 ) that turns less than 8000 Rpms I use 40:1 one that turns more than 8000 I mix at 32:1

Has worked great for me so far...

Jay

[Ron V]

Yamaha started putting reliable oil injection on 2 stroke motorcycles in 1964.

Yeah, and it was injected behind the carburetors, where it should be. Instant mixture change with throttle position. Could that be why my dad's 1965 YDS-3 has 50,000 miles on the original bore and pistons? But, sshhh....don't say the Japs did anything right or better. That would not be good to say that and is not allowable on this forum.

[Mark75H]

We had several YDS-3's. Used them for everything, never a lick of trouble.

[ChrisCarsonMarine]

Sam,they oil injected because they had to.The whole country got around on 30-50 cc scooters,at least those who could afford them.The little motors had to be capable of idling in traffic stops and then
Running full speed,over and over,without fouling the weak magneto fired sparkplug.The oil injection kept the motors lubed without fouling.Don't give em too much credit,what they've got came from us... They have two natural resources...salt and rock,chris

[Mark75H]

Oil injection on a 1964 motorcycle came from the US? Can you give an example?

[ChrisCarsonMarine]

Sam,I wasn't speaking of the oil injection specifically ,just a general observation.It looks to me most of their outboard tech was borrowed from Omc.I don't know where oil injection began,but my dad brought a little car from Germany that looked a little like a streamlined VW bug,a DKW, it had a 3 cyl 2 stroke motor,with a gas tank and an oil tank.l was just a kid when we moved and it was left behind,1963-4?I don't know for sure but I think the Italians and Germans had it long ago,chris

[Mark75H]

That likely is the source of oil injection ... but ...

what they've got came from us

I was pretty sure it wasn't "us" in the US ... I just wanted it clarified for other readers.


All the screaming 2 stroke bike technology was based on Walter Kaaden's work in East Germany's MZ motorcycle shop. A defector took it to Japan where they refined it.

What the Japanese lack in basic research, they make up for in refining other people's ideas. Its a cultural thing for them, they think its the right way.

[modvp]

I too have been adding 0.5 oz/gal for an estimated 1:42 ratio at max rpm. Adding 1 oz would give a ratio of ~1:36.

[Ron V]

Sam,they oil injected because they had to.The whole country got around on 30-50 cc scooters,at least those who could afford them.The little motors had to be capable of idling in traffic stops and then
Running full speed,over and over,without fouling the weak magneto fired sparkplug.The oil injection kept the motors lubed without fouling.Don't give em too much credit,what they've got came from us... They have two natural resources...salt and rock,chris

Well for starters, the YDS models that Sam and I were referring to weren't scooters. Unless you want to use the word "scooter" to describe 250cc sport bikes that put Yamaha on the map by winning races.

Secondly, they didn't have magnetos. They were battery ignition.

There was one fault of the Autolube system - it didn't work while the clutch was pulled in at a stoplight. So it is true that the injection helped prevent fouled plugs from idling . Truthfully, the residual oil was plenty to get through a stoplight change and you could always kick it into neutral and let go of the clutch.

You forgot to mention one other resource the Japs have: BRAINS. Something severely lacking in this country since rampant marijuana use, eyebrow rings, and baggy pants became widely accepted.

[ChrisCarsonMarine]

Ron,sad but so true...

[Madpoodle]

You forgot to mention one other resource the Japs have: BRAINS. Something severely lacking in this country since rampant marijuana use, eyebrow rings, and baggy pants became widely accepted.

Damn, I may have to change my sig line

[ScarabEpic22]

I will vouch for oil injection on my 87 2.4L Laser simply because I have a 60gal gas tank in the Scarab and trying to premix that with solid consistency after multiple refuels would get interesting. I could and would do it, but its officially my parents boat and if they happened to forget at some point, BOOM! There goes a brand new rebuilt powerhead. Not what I want, plus the hull is heavy and Ive never seen above 5800rpms, hopefully post-rebuilt I should be able to spin 6100-6200rpms if I want but will probably keep it around 6000. If I was trying to run race gas and really get the last drop of performance from the motor, first I wouldnt have it on the heavy Scarab hull (but sure makes rough water trips pleasant) and Id definitely remove oil injection and spin 7000+rpms.