How much 2-stroke, and why?

[3beejay3]

Originally Posted by motopsycho87

Because the silly old school measuring system we used to and the yank still do use. Though most bike manufacturers accept this is a good compromise ratio with regards to all round use / emissions etc...

32:1 = 4oz oil to 1 gallon fuel

50:1 = 2%

33:1 = 3%

25:1 = 4%


http://www.howtomotorcyclerepair.com...-2007-2008.pdf - Kawasaki recommend 32:1 in their kx125 and kx250

RM125 recommends 30:1 even with the good stuff!! even though motul recommends themselves 50:1

What makes us think our engines are any different? I can understand if you literally poodle in the woods and never open it up, but I'd hate to have the fear of seizure every time I whack my throttle open!!

It's not the engines being any different, it's how they're set up and actually used.
As I mentioned in the other thread, for fast mx and desert racers(expert & pro level) that can keep a bike WOT almost all the time, 32:1 is a good idea.
Notice the recos you referred to are for mx bikes & the factories always assume those bikes will be on the pipe all the time which is why they also have accelerated service intervals listed in their manuals.

Most woods riders and other plonkers can easily get away with 50:1 as the bikes are only on the pipe a limited amount. Even with 50:1, you can still do lots of WOT runs without fear of damage, or premature wear, provided the bike is jetted properly, or a tad rich.

Currently at 110 hrs on stock top end on my '12 250, which is still in excellent condition. I'm a mid pack Vet B rider.
I have no intention to do a top end til at least 150-200 hrs. I run 60:1 full syn. Bike is jetted rich.

PS I also do extended service oil changes in my vehicles with full synthetic. Got 16,000km out of my last one. (Full size GM pickup 5.3l V8). I'd go a lot more if I had a bypass 1 micron filter system on it.
Used to do 30-40,000 Km between changes (full synthetic, filter changes every 10,000km) on my Diesel VW & it had well over 400,000km on it when I sold it, still running like a top.

Modern oils are better & can do a lot more than most people give them credit for.

[rosco]

I run around 60:1 when woods riding and about 50:1 when racing. I have been using Maxima formula K2. Seems to burn pretty clean and doesn't get carbon buildup on the ex. valve and ex. port.

[noobi]

Originally Posted by motopsycho87

Because the silly old school measuring system we used to and the yank still do use. Though most bike manufacturers accept this is a good compromise ratio with regards to all round use / emissions etc...

32:1 = 4oz oil to 1 gallon fuel

50:1 = 2%

33:1 = 3%

25:1 = 4%


http://www.howtomotorcyclerepair.com...-2007-2008.pdf - Kawasaki recommend 32:1 in their kx125 and kx250

RM125 recommends 30:1 even with the good stuff!! even though motul recommends themselves 50:1

What makes us think our engines are any different? I can understand if you literally poodle in the woods and never open it up, but I'd hate to have the fear of seizure every time I whack my throttle open!!

As others have pointed out also, it depends on the use of the engine as to whether it needs more or less oil. I think my engines are used differently in that, they are almost never revved as far out as they will go, and never for extended periods of time.

I liked the final article you listed, the maximausa oil mitigation test, http://www.maximausa.com/tech-tips/oil-migration.php

The conclusions at the end essentially sum up my feelings on the topic, the table they use at the end is a practical application of how they think oil residence time in the engine relates to how much oil should be there.
As an enduro rider of a 250cc motorcycle, 40:1 falls within their recommendations.

[Pepperami]

40-1 and I have no idea why!

[Mattnzl]

Originally Posted by noobi

Why does 32:1 even exist as a ratio? Is it to do with that wonky other measurement system?.

For metric manufactures, it's the only ratio where people can't stuff it up.
32:1 IS 32ml per litre.

If they specify 40:1, some fools will take that as 40ml oil per litre (thereby actually making a mix of 25:1).

That's my theory anyway!

[bowhunter007]

Originally Posted by Pepperami

40-1 and I have no idea why!

I like it I truly think most fall into the "I don't know why" catagory, including me. I'd prolly be fine running 50:1 in everything...using today's modern synthetics. I'm just too chicken to run leaner. It's not like I don't have any spare engines to blow experimenting

[gasser]

Enduro 2strokes engines are very much like 2stroke trials engines in design. I can see no common sense reason one would "need" 2-3 times as much oil as the other - if both were stressed (rpm and temp) the same. My point I'm trying to make here is stress dictates the oil needs of any given engine even more than the engine design does. While it is true that more oil means better ring sealing and more power not everyone of us are racers. Does it matter to me if my ec250 produces 40hp rather than 39.5? Of course not. Does it matter that the top end will go 400 hours rather than 300 between freshening? Of course not - I choose to do it every 200 hours for my own peace of mind. Choose what works for you in the long run.

[gasser]

Originally Posted by Mattnzl

For metric manufactures, it's the only ratio where people can't stuff it up.
32:1 IS 32ml per litre.

If they specify 40:1, some fools will take that as 40ml oil per litre (thereby actually making a mix of 25:1).

That's my theory anyway!

Matt you have a good point. Here in the U.S. where we haven't fully converted to the metric system for fluids we use ounces, quarts, and gallons. A U.S. gallon has 128 ounces.
8 ounces/gallon = 16/1
4 ounces/gallon = 32/1
3 ounces/gallon = 43/1
2 ounces/gallon = 64/1
1.5 /gallon = 85/1

[Bandit9]

Originally Posted by Coop

Have you actually read your Gas Gas owner's manual? Mine says 50:1 synthetic, 32:1 non-synthetic.

You mean you actually got a manual with your bike?

[coopernicus]

Here are my thoughts as I've always wondered about oil ratios but never had the means or time to test myself. When I bought my first premix bike I was told by the dealer (lots of MX and Off road racing experience) to use a 12 ounce bottle of Golden Spectro for 4 gallons of gas (roughly 43:1) as that had been working for him and his shop for many years. It worked for me then and it does now using either Klotz R-50 or Spectro. I've always had a good bit of spooge and each time I disassemble for a rebuild there is a film of oil on everything. Also, no seizures or bearing failures in doing this for almost 35 years of racing and trail riding both air cooled and water cooled bikes. When I first asked about the "annoying spooge and film" he called me an idiot and said that is what protected the bike during and after operation. I couldn't argue with that and this ratio using both Spectro and Klotz R-50 is what I tell everyone I use (I do not recommend oil and ratios, I just tell people what I have been successful using since the late '70s). As always, your results may vary because you are not me, you don't have the same bike setup as I do, you don't get gasoline from the same place that I do, and your riding conditions are not the same as ride.
I have read all of the articles posted in the first message of this thread and believe those that have done actual tests are excellent for their purpose. However, some of their "purposes" do not match mine. I don't ride my bike like an RC Plane or an Ultralight. I don't ride it like a vintage air cooled road racer, either. Someone asked "what is different with newer motors" (summarizing) and there are many: 1970's air cooled motors were very sloppy in the tolerances, they had very inconsistent cooling patterns on the cylinder walls based upon fin size and exhaust port layout, and their metallurgy was often suspect at best (especially a late '70s Suzuki PE-250). Back then a lot of oil was needed for ring sealing because of the reverse "hour glass" wear pattern in the cylinder that wore in quicker due to air/fuel mixture, cooling pattern, and air filtration issues. Back then, as is today, you should fear improper jetting and poor air filtration far more than the oil ratios discussed on this forum. I am glad I read all of the noted articles as they are interesting and educational for their time and purpose. I believe the best thing to do is pick an oil and ratio you feel comfortable with based upon these articles, recommendations from friends and dealers, and what your manual says (please remember, though, lawyers typically direct content like this in manufacturer manuals). Then, as you service your bike over time, note the wear and deposits so you can decide for yourself what you feel is best for your purpose. In sum, whatever ratio you use "own it" because you chose it using inputs from others where you can't get the experience/tests yourself in a reasonable time and at a reasonable cost. If you want to make your choice off of one of the articles cited above, I believe the most in the Maxima article. I've never used their oil but their test looks more recent and, being a manufacturer, they could make more money by telling me to run at 20:1 but they did not...Hmmm, don't they want some more of my money?

Eric