Oil ratio debate for 2-strokes


21 replies to this topic
  • Pro_Marinero

Posted January 21, 2005 - 04:21 AM

#1

I posted this on a CR500 forum I visit:

Here's a question sure to spark debate. I've always run synthetic Red Line at 40:1. My dad has been working on air-cooled 2-strokes since before I was born. I was tearing down my '97 500 and he asked me what ratio I ran my oil at. We started talking about ratios for different stuff and I brought up the Amsoil 100:1 stuff out now. I mentioned that I would be pretty skeered about running something like that. He mentioned that he has sold an Oregon 100:1 mix for quite awhile for chainsaws and has never had a problem with them. He contrasted a liquid-cooled modern mx motor in fairly optimum conditions temp-wise that isn't wfo all day versus an air-cooled saw that has the throttle mashed down, the motor loading up big time, and the fins packed all full of sawdust and dirt. I figured he had a point and the Red Line Oil I use states it can be mixed up to 100:1, but that's a step I'm not willing to take. I was wondering what's the highest ratio in here people have heard of going to for bikes?

  • PumkinFest

Posted January 21, 2005 - 04:34 AM

#2

I used to run 50:1 in my RM125, is that not pritty high for a race bike? It was never raced though. My boat runs at 100:1 does that count?

  • st3ve

Posted January 21, 2005 - 06:17 AM

#3

i run 32:1 and keep it jetted right, it may not always be the fastest but i rather have a bike thats slightly slower then on the verge of melt down. ive heard of boats running 100:1, and i think 50:1 would be acceptable in a 500 or any big bore. they dont rev..so whats the point of having all that oil?

  • SC_Spode

Posted January 21, 2005 - 06:19 AM

#4

I posted this on a CR500 forum I visit:

Here's a question sure to spark debate. I've always run synthetic Red Line at 40:1. My dad has been working on air-cooled 2-strokes since before I was born. I was tearing down my '97 500 and he asked me what ratio I ran my oil at. We started talking about ratios for different stuff and I brought up the Amsoil 100:1 stuff out now. I mentioned that I would be pretty skeered about running something like that. He mentioned that he has sold an Oregon 100:1 mix for quite awhile for chainsaws and has never had a problem with them. He contrasted a liquid-cooled modern mx motor in fairly optimum conditions temp-wise that isn't wfo all day versus an air-cooled saw that has the throttle mashed down, the motor loading up big time, and the fins packed all full of sawdust and dirt. I figured he had a point and the Red Line Oil I use states it can be mixed up to 100:1, but that's a step I'm not willing to take. I was wondering what's the highest ratio in here people have heard of going to for bikes?


You're right, it will get people worked up, but facts are facts.

There was a post on here recently by someone who worked on outboard engine development and tested the effects of oil/fuel ratios on power and durability of engine components.
It revealed that mixtures with greater amounts of oil provide more power and engine protection than those with lower amounts. Meaning a 16:1 mix performed better than a 100:1 mix.
This isn't the first time I've seen this concluded from testing and I believe you'll find that people like Rich Rohrich that do research on these subjects will confirm this, also.

There is a lot of agreement that a 32:1 ratio (4 oz/gal) provides satisfactory protection and performance. A number of manufacturers have also recommended this ratio for their bikes.

I've been mixing 32:1 for over 25 years, jet accordingly and have never had an oil related failure. I also get incredible life out of my 2-stroke engines, so my experiences would back up the 32:1 recommendation.

:cry:

  • Silver Surfer

Posted January 21, 2005 - 07:02 AM

#5

i used to run 24:1 with yamalube for trail riding in a yz125. sure there's a lot of smoke, but my top ends last forever. the bike is a 91 and i rebuilt the bottom for the first time this fall. it didn't need it, but i did it anyway.

aftter hearing that yamalube was a trashy oil (and the gunk in the power valve assembly was proof), i switched to golden spectro and run it an 40:1. so far no problems.

i would be nervous about running any ratio past 50:1 as well. i think chainsaw and boat motor manufactures recommend these high ratios, but bike manufactures do not. its probly for a reason.

  • beezer

Posted January 21, 2005 - 07:09 AM

#6

32 to 1 is what I always ran in my smokers with good results.

100 to 1 is asking for a melted motor.

I have a few 2 stroke street bikes and run them on Klotz oil with zero problems.

  • therapture

Posted January 21, 2005 - 07:11 AM

#7

32:1 is the premium ratio :cry: I run my lawnmower, weedeater, etc., all on the same oil and ratio...used to do the same with my 2-smoke dirt bikes too...never, ever, had an issue.

  • cruise

Posted January 21, 2005 - 07:29 AM

#8

I use motul at 50:1 in my 125 and the plug is a good color. I tried 32:1 and it blew a lot of smoke. Should i play with the jetting ? if so should i go leaner or richer. My alt is 60 ft and the temp is 80 to 100 any sugestions would be aprieciated. It's a 2002 yz125 it has a fresh top end.

  • vmaxcbr900wr426

Posted January 21, 2005 - 07:31 AM

#9

I'm running 40:1 Amsoil right now in my 04' 300 EXC. The bike was nearly brand new when I bought it and that's what the guy was running and the jetting is spot on.

I ran Duralube at 50:1 for years with no problems at all both the air cooled version and the Water Pumper version. Pull the head and every bike was clean inside.

When I ran Golden Spectro at the same ratio, nothing but splooge out the pipe and tons of build up inside the cylinder. I'd never use that stuff again, even in my Stihl blower and weedeater.

  • SC_Spode

Posted January 21, 2005 - 10:43 AM

#10

I use motul at 50:1 in my 125 and the plug is a good color. I tried 32:1 and it blew a lot of smoke. Should i play with the jetting ? if so should i go leaner or richer. My alt is 60 ft and the temp is 80 to 100 any sugestions would be aprieciated. It's a 2002 yz125 it has a fresh top end.


cruise,

I'll try to explain this clearly since a lot of people seem to get confused with this subject.

If you go from 50:1 to 32:1 you are going to a richer gas/oil mixture.

This makes the mixture thicker, therefore it does not flow as easily as before.
(Which leans out your fuel/air mixture.)

You will need to richen your jetting if you make this change. This is a richer fuel/air mixture.

If it helps, think of the extremes: If you had straight premix oil in there it would be very thick (heavy) and if you had straight gas in there it would be very thin (light).
The gas would flow much easier than the oil.
Therefore, the oil-only scenario would require richer jetting (bigger holes) than the gas-only situation to allow it to flow at the proper fuel/air ratio.

The brand of oil will also influence the amount of smoke you see. Some burn cleaner than others.

My last CR500 was run at 32:1 and was jetted so crisply that the plug was dry and tan and there was no gunk in the silencer. And it ran forever on the stock bore; never wore it out before I sold it.

:cry:

  • MajorDanage

Posted January 21, 2005 - 11:54 AM

#11

I run the 100:1 Amsoil Premix but I run it at 80:1 in my 02 YZ250. I've can't say for sure if it was because of the oil but I had to replace my crack at the end of this year. I think it had more to do with the amount of dirt that got sucked through the filter after I didn't clean it for a month. Oops. The bike runs great now and I couldn't be happier. Its really easy to mix too. Although I like just driving up to the pumps on my wr250f, filling up, and going. It even easier.

  • canadaler

Posted January 21, 2005 - 01:39 PM

#12

IMO people really get paranoid about going "past" about 32:1.

I used AMSOIL synthetic for three years in my 200EXC KTM @ 80:1, no problems...none. It was torn down each year and I replaced one piston. I'm sure that would have still had to be done even running at lower oil ratios. There was always plenty of lubrication present in the bearings and surfaces each time I inspected. This was on a bike which did weekly Hare Scrambles and Enduro racing...it had high hours on it at high RPM.

What ratio you run is (again IMO) highly dependant on what oil you run...use a quality synthetic you CAN go 80, (or even 100:1 for less severe non racing applications.) Use an "old fashion" (like castor) oil and you better stick to 32:1, or less.

Lots of people say "I only run 32:1 and have no problems." That doesn't prove that higher ratios (with the right oil) are not OK.

Somebody out there who has run 80/90/100:1 and had problems that are documented from being caused by lack of lubrication? ....speak up.

  • SC_Spode

Posted January 21, 2005 - 02:17 PM

#13

Somebody out there who has run 80/90/100:1 and had problems that are documented from being caused by lack of lubrication? ....speak up.


See, I told you this gets people worked up! :cry:

canadaler,

I've seen plenty of bikes run fine on the leaner oil/fuel mixtures. However, I've also read the reports (and seen some of the data) that shows that an engine produces more power and experiences less wear with richer oil/fuel mixtures.
These are measured, documented facts, not opinions.
Doesn't mean that you can't be happy with a leaner mixture, just that a richer one offers more power and protection.

I haven't been able to find the reports I'm thinking about but if someone else reading this thread can steer everyone else to some of these, I'm sure it would be appreciated.

:cry:

  • Hokie

Posted January 21, 2005 - 02:26 PM

#14

I've can't say for sure if it was because of the oil but I had to replace my crack at the end of this year.


Too Much Information!

:cry:


PS - I use 32:1 in both my 300 and 200, Castrol TTS.

  • SC_Spode

Posted January 21, 2005 - 02:48 PM

#15

I copied this from another forum to provide more info:


I was involved in an oil ratio test for Mercury Marine. We tested various oil ratios on a few different outboard engines that were commonly used in racing. We did not test every engine, as many engines were similar designs with different rated outputs (a common trick in outboards). We partly based our testing on some industry information by a chain saw and go kart engine company (Mcculloch).

In any case (for the most part) the oil used was Factory outboard oil. We did try other oils without much HP difference.

Oil ratio's covered the extreme range.

The bottom line is that more oil made more power. The standard 50 to 1 ratio was sufficient to provide lubrication without operational problems such as smoke and plug fouling. 32 to 1 made more power and 16 to 1 made even more power. We even tried ultra rich ratio's like 8 to 1 or 5 to 1 and power did improve to a point even at the extreme end of the test. 100 to 1 did show a significant loss of power. This was not designed to be an oil test to end all tests, just a way to determine how to make more power for certain racing classes,

While the test was not designed to indicate wear, I did draw some basic conclusions. In racing applications more oil reduced wear slightly. This is as you might expect. What we saw is that any normal oil ratio protects the engine well. Lean oil ratios seemed to work well until the temperature and stress got out of hand. That is where a lean ratio would not be enough for full protection.

I have since read that oil ratio's around 32 to 1 provide nearly all the protection that is available for most performance engines. My experience backs that up. Yes, there would seem to be some extreme examples of engines that need 16 to 1. I am not sure I can draw a conclusion as to which engines need this level of lubrication, but I would guess it would be well out of the norm, especially for dirt bike applications.

Another note on 2 stroke lubrication, upon teardown, any reasonable ratio will leave a significant amount of oil on internal engine parts. While many people think the oil just races through a 2 stroke engine, this really is not the case. It does separate from the gas and lubricate the bearings, con rod, and piston skirt in full force.


I think to get a definitive answer as to what ratio works best for a specific oil, you would need to do some testing of your own (this is due to different formulations and the goals of each manufacturer).
I would hope the manufacturer has done this prior to marketing it and arrived at an optimum ratio for their oil, in which case I would go with their recommendation. If they have none, I use 32:1.

So, if you and your bike are happy with your current mixture, leave it alone! :cry:

BTW, does anyone know where I can get Blue Marble oil? I haven't seen it around here.

:cry:

  • RichBaker

Posted January 21, 2005 - 03:04 PM

#16

More oil seals the rings better, resulting in better compression and more horsepower.....I always run 24:1 in my YZ250, the current top-end is 10 years old and I notice a slight power loss on high-altitude hill climbs. She starts 2nd kick cold, 1st kick hot.......get lots of spooge from the exhaust in slow sections, but I don't care.
For power and longevity run more oil!

  • hill5150

Posted January 21, 2005 - 03:11 PM

#17

:cry: I've ran Maxima castor and reg blue my entire 20 years of riding skis and bikes at 3 oz to the gallon, never seized and have ALWAYS had good results. Better to run a bit :cry: rich and have a full wallet than run lean with no wallet.Good luck.......... :cry:

  • trx310r

Posted January 21, 2005 - 03:24 PM

#18

Good oil 80-125cc 32-36:1 250 and up 40:1 Worked for me.

  • sageone

Posted January 21, 2005 - 05:49 PM

#19

Golden Spectro Semi-synthetic 52:1, that's what the label says. Usually, the oil manufacturer will know best. Good Luck :cry:

  • Ride

Posted January 21, 2005 - 06:44 PM

#20

cruise,

I'll try to explain this clearly since a lot of people seem to get confused with this subject.

If you go from 50:1 to 32:1 you are going to a richer gas/oil mixture.

This makes the mixture thicker, therefore it does not flow as easily as before.
(Which leans out your fuel/air mixture.)

You will need to richen your jetting if you make this change. This is a richer fuel/air mixture.

If it helps, think of the extremes: If you had straight premix oil in there it would be very thick (heavy) and if you had straight gas in there it would be very thin (light).
The gas would flow much easier than the oil.
Therefore, the oil-only scenario would require richer jetting (bigger holes) than the gas-only situation to allow it to flow at the proper fuel/air ratio.

The brand of oil will also influence the amount of smoke you see. Some burn cleaner than others.

My last CR500 was run at 32:1 and was jetted so crisply that the plug was dry and tan and there was no gunk in the silencer. And it ran forever on the stock bore; never wore it out before I sold it.

:cry:


Spode...

I think your almost right here. A bike does run RICHER with less oil but it is because of the fuel/oil ratio not the "thickness" of the oil mixture. Rich or lean is a ratio of air to fuel (which is the mix of gas and oil). When you jet leaner you are going smaller on a jet that makes less fuel available for the same amount of air. Mix more oil with the gas there is less gas to that same amount of air because now a bigger portion of the fuel mixture is oil NOT gas.

Now I'm not surprised that more oil produces more power. I would think it would have to make the engine run longer as well. The oil is there to lubricate, the more there is the more the engine is lubricated so it spins more free and hence makes more power and lasts longer.

A buddy of mine always bitches about the spooge on his two stroke, I always tell him there is nothing wrong with that as long as your bike carburates right and makes good power.

As far as the original chain saw WFO with saw dust in the fins I think the power to weight ratio is way different.

A high end chain saw - Husqvarna Model 385XP/XPG Chainsaw, 85 cc, 6.3 HP"

YZ85 - 21.3 kW (29.0 HP) @ 12000 rpm

So for the same displacement the YZ makes 4.6 times the HP. Additionally I think the chain saw rev about a third as high.

I like posts that make me think. :cry:

:cry:





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