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Offline JohnN

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Re: Oil and ratios
« Reply #15 on: January 23, 2010, 03:17:25 AM »
admin, i'm just kidding. every oil thread i've ever seen on the internet turns personal. i hope this place is different because honestly someone could run canolla oil for all i care.

Admiral, I knew that you were joking.... just having some fun!

What about popcorn scented oil?? Mmmmm Yummmy!  ;D ;D
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Offline admiral

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Re: Oil and ratios
« Reply #16 on: January 23, 2010, 06:59:39 AM »
hot dog! an oil thread. where's the personal attacks?

Since you asked,I'll start.I wouldn't give a mouldy hotdog for your your oil theories admiral-hee,hee.Hows that.Anyhoo,years ago MacCulloch,of chainsaw fame at the time,did extensive testing and found to best power/performance to be had at a ratio of 12:1.Mind you,oils today are obviously different but I always thought that was interesting.
oh yeah? :P well just to horrify the oil zealots, i will tell you that i almost always run a "witch's brew" of 2T oil. i routinely blend different brands together. a few years ago when the distributor Motorcycle Stuff was in it's final year of operation, i was given a sample 12L case of Repsol moto2T oil. they had just started carring the oil line. the stuff was clear like baby oil. you couldn't tell at a glance whether you had a gallon of premix or a gallon of straight gas. so i got a clean 5 gal. bucket and emptied the Repsol bottles into it then scoured the shop for half used bottles of any 2T oils i could find. i mixed in some Klotz R-50, Honda HP-2, Motul 800, Mobil 2T,and Redline. those oils were red and blue so they made purple and dyed the clear Repsol purple. i have ran that stuff through my mx bikes, both my outboard motors, chain saws, and weed wackers. i'm still using it up.

Offline Chokey

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Re: Oil and ratios
« Reply #17 on: January 24, 2010, 07:20:35 PM »
Hello everyone. I'm new here, and just thought I would start with a bang! This is my personal take on mix ratios.

Pre-Mix 101

Looks like it's time for a little pre-mix 101. I don't usually get into ratio discussions, because mix ratios are like religions to most people, and they tend to be closed-minded and hard-headed on the subject, but I'll put in my $.02 here anyway.

Anyone that believes that spooge and plug fouling are caused by too much oil in the mix is flat out wrong. If you know how to jet, you can run any amount of oil you choose, and have absolutely zero spooge.

There is a prevailing myth that less oil is better. This simply isn't the case. While there isn't a magic "one-size-fits-all" mix ratio, and it is possible to use too much oil for your conditions, generally speaking, more oil is better, within certain limitations.

When an engine is jetted too rich, the excess fuel leeches heat from the combustion process, causing the combustion chamber temperatures to be too low to effectively burn the oil, or even completely burn all of the fuel. The result is spooge and deposits. The spooge is nothing more than unburned fuel and oil passing out the exhaust.

If you have a spooge problem, you have a jetting problem. You don't get rid of the spooge by reducing the oil, you get rid of it by fixing the jetting. Correct jetting will produce an air/fuel ratio of about 14:1, which will produce combustion temperatures in the 6000F range and exhaust temperatures in the 1200F range. This will provide sufficient heat to consume the premix oil.

The same goes for plug fouling. Rich jetting does two things. First, it promotes incomplete combustion of the fuel and the oil due to reduced combustion temperatures. The incomplete combustion of the fuel and oil promotes deposit formation inside the engine. Second, rich jetting reduces the combustion temperatures, which in turn reduces the engines ability to burn off deposits. Combine increased deposit formation with reduced ability to burn off those deposits, and what do you get? Spooge and plug fouling.

You don't choose a mix ratio based on "spooge" or plug fouling, you choose the ratio based on the amount of oil your engine needs to provide sufficient protection and adequate ring seal. The common misconception is that mix ratios are "one-size-fits-all", when in fact nothing could be farther from the truth.The amount of oil that is correct for one rider on his bike may not be enough oil for another rider/bike, or it may be too much oil. It all depends on engine displacement, riding style, and how hard you push the engine. A trail rider on a 500 that never reams the bike out is probably fine on a diet of 50:1, where a super-fast up-and-coming young future pro that screams an 85 'till the dogs howl the entire time he's on the track might not get a full day of racing out of an engine on less than 30:1. Your engine's oil needs are determined by displacement, rev range, and the loads you put on your engine.

When you shut your engine down and let it sit, much of the oil drains down into the crankcase and forms a puddle in the bottom. The depth of this puddle is your indicator of whether you are running the correct amount of oil for your engine's needs. Ideally, you want this puddle to be between 1/8 and 1/4 inch. If it's less, you need more oil in your mix. If it's more, you are running more oil than you need for your conditions.

With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 32:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.

When I was much younger and a lot faster, 32:1 wasn't enough oil for my conditions. I needed 26:1 to have enough oil. And I have run as much as 18:1 with no spooge or plug fouling issues.

To understand why the mix ratio is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine. The oil mist is distributed throughout the engine by the spinning crankshaft and the moving air currents to coat all the internal surfaces.

People believe that the oil just rushes right through a two-stroke along with the fuel, but that just isn't so. It can take 90 minutes or more for the oil migration through a two-stroke to result in a complete oil exchange on a slow trail ride, and even as much as 5 minutes for a full-throttle 20 minute moto.

The oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1 in a small-bore engine, you simply can't jet very lean without risking a seized engine due to oil starvation.

One small point. No one ever broke an engine by using too much oil.

Now we come to the issue of ring seal. Simply put, the rings alone can not effectively seal the cylinder. They also need oil to provide a complete seal against the bore surface. And up to a point, more oil will provide a better seal.

I have run Dyno tests on this subject, as a school project in Tech School. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially calibrated jets to ensure the fuel flow was identical with each different ratio, and warmed the engine at 3000 rpm for 3 minutes before each run. Our tests were performed in the rpm range of 2500 to 9000 rpm, with the power peak of our test bike (an '86 YZ 250) occuring at 8750 rpm. We tested at 76 degrees F, at 65% relative humidity. We started at 10:1, and went to 100:1. Our results showed that a two-stroke engine makes its best power at 18:1. Any more oil than that, and the engine ran poorly, because we didn't have any jets rich enough to compensate for that much oil in the fuel. The power loss from 18:1 to 32:1 was approximately 2 percent. The loss from 18:1 to 50:1 was nearly 9 percent. On a modern 250, that can be as much as 4 horsepower. The loss from 18:1 to 100:1 was nearly 18 percent. The reason for the difference in output is simple. More oil provides a better seal between the ring and the cylinder wall.

Now, I realize that 18:1 is impractical unless you ride your engine all-out, keeping it pinned at all times. But running reasonable ratios no less than 32:1 will produce more power, and give your engine better protection, thus making it perform better for longer.

The bottom line? Choose a mix ratio that is adequate for your needs, and jet accordingly. You don't fix plug fouling and spooge by adjusting your mix ratio.[/color

This is an interesting read that also supports my "more oil is better" claim.

http://www.bridgestonemotorcycle.com...oilpremix6.pdf

And this is a good article as well:

http://www.maximausa.com/technical/l...summer2001.pdf

Offline TotalNZ

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Re: Oil and ratios
« Reply #18 on: January 24, 2010, 07:42:26 PM »
Hello everyone. I'm new here, and just thought I would start with a bang! This is my personal take on mix ratios.

Pre-Mix 101

Looks like it's time for a little pre-mix 101. I don't usually get into ratio discussions, because mix ratios are like religions to most people, and they tend to be closed-minded and hard-headed on the subject, but I'll put in my $.02 here anyway.

Anyone that believes that spooge and plug fouling are caused by too much oil in the mix is flat out wrong. If you know how to jet, you can run any amount of oil you choose, and have absolutely zero spooge.

There is a prevailing myth that less oil is better. This simply isn't the case. While there isn't a magic "one-size-fits-all" mix ratio, and it is possible to use too much oil for your conditions, generally speaking, more oil is better, within certain limitations.

When an engine is jetted too rich, the excess fuel leeches heat from the combustion process, causing the combustion chamber temperatures to be too low to effectively burn the oil, or even completely burn all of the fuel. The result is spooge and deposits. The spooge is nothing more than unburned fuel and oil passing out the exhaust.

If you have a spooge problem, you have a jetting problem. You don't get rid of the spooge by reducing the oil, you get rid of it by fixing the jetting. Correct jetting will produce an air/fuel ratio of about 14:1, which will produce combustion temperatures in the 6000F range and exhaust temperatures in the 1200F range. This will provide sufficient heat to consume the premix oil.

The same goes for plug fouling. Rich jetting does two things. First, it promotes incomplete combustion of the fuel and the oil due to reduced combustion temperatures. The incomplete combustion of the fuel and oil promotes deposit formation inside the engine. Second, rich jetting reduces the combustion temperatures, which in turn reduces the engines ability to burn off deposits. Combine increased deposit formation with reduced ability to burn off those deposits, and what do you get? Spooge and plug fouling.

You don't choose a mix ratio based on "spooge" or plug fouling, you choose the ratio based on the amount of oil your engine needs to provide sufficient protection and adequate ring seal. The common misconception is that mix ratios are "one-size-fits-all", when in fact nothing could be farther from the truth.The amount of oil that is correct for one rider on his bike may not be enough oil for another rider/bike, or it may be too much oil. It all depends on engine displacement, riding style, and how hard you push the engine. A trail rider on a 500 that never reams the bike out is probably fine on a diet of 50:1, where a super-fast up-and-coming young future pro that screams an 85 'till the dogs howl the entire time he's on the track might not get a full day of racing out of an engine on less than 30:1. Your engine's oil needs are determined by displacement, rev range, and the loads you put on your engine.

When you shut your engine down and let it sit, much of the oil drains down into the crankcase and forms a puddle in the bottom. The depth of this puddle is your indicator of whether you are running the correct amount of oil for your engine's needs. Ideally, you want this puddle to be between 1/8 and 1/4 inch. If it's less, you need more oil in your mix. If it's more, you are running more oil than you need for your conditions.

With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 32:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.

When I was much younger and a lot faster, 32:1 wasn't enough oil for my conditions. I needed 26:1 to have enough oil. And I have run as much as 18:1 with no spooge or plug fouling issues.

To understand why the mix ratio is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine. The oil mist is distributed throughout the engine by the spinning crankshaft and the moving air currents to coat all the internal surfaces.

People believe that the oil just rushes right through a two-stroke along with the fuel, but that just isn't so. It can take 90 minutes or more for the oil migration through a two-stroke to result in a complete oil exchange on a slow trail ride, and even as much as 5 minutes for a full-throttle 20 minute moto.

The oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1 in a small-bore engine, you simply can't jet very lean without risking a seized engine due to oil starvation.

One small point. No one ever broke an engine by using too much oil.

Now we come to the issue of ring seal. Simply put, the rings alone can not effectively seal the cylinder. They also need oil to provide a complete seal against the bore surface. And up to a point, more oil will provide a better seal.

I have run Dyno tests on this subject, as a school project in Tech School. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially calibrated jets to ensure the fuel flow was identical with each different ratio, and warmed the engine at 3000 rpm for 3 minutes before each run. Our tests were performed in the rpm range of 2500 to 9000 rpm, with the power peak of our test bike (an '86 YZ 250) occuring at 8750 rpm. We tested at 76 degrees F, at 65% relative humidity. We started at 10:1, and went to 100:1. Our results showed that a two-stroke engine makes its best power at 18:1. Any more oil than that, and the engine ran poorly, because we didn't have any jets rich enough to compensate for that much oil in the fuel. The power loss from 18:1 to 32:1 was approximately 2 percent. The loss from 18:1 to 50:1 was nearly 9 percent. On a modern 250, that can be as much as 4 horsepower. The loss from 18:1 to 100:1 was nearly 18 percent. The reason for the difference in output is simple. More oil provides a better seal between the ring and the cylinder wall.

Now, I realize that 18:1 is impractical unless you ride your engine all-out, keeping it pinned at all times. But running reasonable ratios no less than 32:1 will produce more power, and give your engine better protection, thus making it perform better for longer.

The bottom line? Choose a mix ratio that is adequate for your needs, and jet accordingly. You don't fix plug fouling and spooge by adjusting your mix ratio.[/color

This is an interesting read that also supports my "more oil is better" claim.

http://www.bridgestonemotorcycle.com...oilpremix6.pdf

And this is a good article as well:

http://www.maximausa.com/technical/l...summer2001.pdf

WORD!

Offline JohnN

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Re: Oil and ratios
« Reply #19 on: January 25, 2010, 04:18:41 AM »
I thought your other post was good!! Damn, this is the best explanation of oil mix ratios that I have ever read.

Thank you.
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Offline Helmut Clasen

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Re: Oil and ratios
« Reply #20 on: January 25, 2010, 07:22:10 AM »
Like I said before,,
It is just like religion.You never come to a 100 % conclusion.

Fact for me is:
Since the early 70s when MY oil came to Canada,I have used it in all my Vintage and Modern bikes at a mix rate of 100-1 in MX in HS in Enduros in ISDTs(and that is 6 days brutal on the engine) and never ever had a failure.Never a piston sizer,nothing.
That MORE OIL  (look what Hydraulic is doing) show more power on a DYNO is well known.But DYNO and real life is a lot of difference.
Piston-Pistonring and modern cylinder material(plating etcetera)have reached a quality which gives factorys (like KTM) which are very carefull what they suggesting) a recommendet oil ratio from(always depend what oil) from up to 80 to 1.
I always tought my customers to mix what the bottle says.And have the carb jetted accordingly.After that,stick to the same brand of OIL and even Gasoline  .
Otherwise,...whatever makes you happy. ;D ;)


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Offline Chokey

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Re: Oil and ratios
« Reply #21 on: January 25, 2010, 06:42:03 PM »
Like I said before,,
It is just like religion.You never come to a 100 % conclusion.

Fact for me is:
Since the early 70s when MY oil came to Canada,I have used it in all my Vintage and Modern bikes at a mix rate of 100-1 in MX in HS in Enduros in ISDTs(and that is 6 days brutal on the engine) and never ever had a failure.Never a piston sizer,nothing.
That MORE OIL  (look what Hydraulic is doing) show more power on a DYNO is well known.But DYNO and real life is a lot of difference.
Piston-Pistonring and modern cylinder material(plating etcetera)have reached a quality which gives factorys (like KTM) which are very carefull what they suggesting) a recommendet oil ratio from(always depend what oil) from up to 80 to 1.
I always tought my customers to mix what the bottle says.And have the carb jetted accordingly.After that,stick to the same brand of OIL and even Gasoline  .
Otherwise,...whatever makes you happy. ;D ;)
Starting lines and trail heads all over the country are filled with bikes running anything from 20:1 to 100:1, with anything from 10W-40 engine oil to Weedeater oil, and most of them live to play another day. That doesn't neccessarily mean it's the best thing for your engine, it just means that modern engine design and metalurgy has gotten so good that the engines are more tolerant than ever to "less-than-optimal" owner practices. But you're right, it's like a religion, and most people will run what they believe to be best. And I'm good with that! If it works for you, that's great.

Offline 2T Institute

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Re: Oil and ratios
« Reply #22 on: January 27, 2010, 03:28:02 AM »
Chokey something very similar to Pre-mix 101 was originaly posted by a fellow called 'Spanky' ??

Have always will always use a castor/synthetic blend at 18-20:1, oils have not realy changed nor have crankpins and needle rollers.Nothing provides the same protection as castor, that begins to work when sythetic /mineral cries enough.
Yes 'spooge' is a indication of incorrect jetting and ignition. GP125's blow a whiff of smoke when the light goes green, that's it in 45mins of racing.

Offline Chokey

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Re: Oil and ratios
« Reply #23 on: January 27, 2010, 04:43:16 PM »
Chokey something very similar to Pre-mix 101 was originaly posted by a fellow called 'Spanky' ??


And that would be me. I also go by Spanky on some forums, although none of them are very active anymore.

Offline mxaniac

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Re: Oil and ratios
« Reply #24 on: February 19, 2010, 04:17:26 PM »
I for the most part agree with all of this.  Spooge can be hard to avoid when you have large temperature swings unless you are willing to constantly reject and with the aluminum framed bikes that can be a real PITA.

I've noticed that spark arrestors will spooge more than silencers.  While it is possible that is just a jetting issue I suspect that the arrestor lowers the exit temp of the exhaust gas and causes the spooge to drop out of suspension.

My experience has been that lower rod end bearings fail first from a lack of 2T oil.


Hello everyone. I'm new here, and just thought I would start with a bang! This is my personal take on mix ratios.

Pre-Mix 101

Looks like it's time for a little pre-mix 101. I don't usually get into ratio discussions, because mix ratios are like religions to most people, and they tend to be closed-minded and hard-headed on the subject, but I'll put in my $.02 here anyway.

Anyone that believes that spooge and plug fouling are caused by too much oil in the mix is flat out wrong. If you know how to jet, you can run any amount of oil you choose, and have absolutely zero spooge.

There is a prevailing myth that less oil is better. This simply isn't the case. While there isn't a magic "one-size-fits-all" mix ratio, and it is possible to use too much oil for your conditions, generally speaking, more oil is better, within certain limitations.

When an engine is jetted too rich, the excess fuel leeches heat from the combustion process, causing the combustion chamber temperatures to be too low to effectively burn the oil, or even completely burn all of the fuel. The result is spooge and deposits. The spooge is nothing more than unburned fuel and oil passing out the exhaust.

If you have a spooge problem, you have a jetting problem. You don't get rid of the spooge by reducing the oil, you get rid of it by fixing the jetting. Correct jetting will produce an air/fuel ratio of about 14:1, which will produce combustion temperatures in the 6000F range and exhaust temperatures in the 1200F range. This will provide sufficient heat to consume the premix oil.

The same goes for plug fouling. Rich jetting does two things. First, it promotes incomplete combustion of the fuel and the oil due to reduced combustion temperatures. The incomplete combustion of the fuel and oil promotes deposit formation inside the engine. Second, rich jetting reduces the combustion temperatures, which in turn reduces the engines ability to burn off deposits. Combine increased deposit formation with reduced ability to burn off those deposits, and what do you get? Spooge and plug fouling.

You don't choose a mix ratio based on "spooge" or plug fouling, you choose the ratio based on the amount of oil your engine needs to provide sufficient protection and adequate ring seal. The common misconception is that mix ratios are "one-size-fits-all", when in fact nothing could be farther from the truth.The amount of oil that is correct for one rider on his bike may not be enough oil for another rider/bike, or it may be too much oil. It all depends on engine displacement, riding style, and how hard you push the engine. A trail rider on a 500 that never reams the bike out is probably fine on a diet of 50:1, where a super-fast up-and-coming young future pro that screams an 85 'till the dogs howl the entire time he's on the track might not get a full day of racing out of an engine on less than 30:1. Your engine's oil needs are determined by displacement, rev range, and the loads you put on your engine.

When you shut your engine down and let it sit, much of the oil drains down into the crankcase and forms a puddle in the bottom. The depth of this puddle is your indicator of whether you are running the correct amount of oil for your engine's needs. Ideally, you want this puddle to be between 1/8 and 1/4 inch. If it's less, you need more oil in your mix. If it's more, you are running more oil than you need for your conditions.

With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 32:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.

When I was much younger and a lot faster, 32:1 wasn't enough oil for my conditions. I needed 26:1 to have enough oil. And I have run as much as 18:1 with no spooge or plug fouling issues.

To understand why the mix ratio is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine. The oil mist is distributed throughout the engine by the spinning crankshaft and the moving air currents to coat all the internal surfaces.

People believe that the oil just rushes right through a two-stroke along with the fuel, but that just isn't so. It can take 90 minutes or more for the oil migration through a two-stroke to result in a complete oil exchange on a slow trail ride, and even as much as 5 minutes for a full-throttle 20 minute moto.

The oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1 in a small-bore engine, you simply can't jet very lean without risking a seized engine due to oil starvation.

One small point. No one ever broke an engine by using too much oil.

Now we come to the issue of ring seal. Simply put, the rings alone can not effectively seal the cylinder. They also need oil to provide a complete seal against the bore surface. And up to a point, more oil will provide a better seal.

I have run Dyno tests on this subject, as a school project in Tech School. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially calibrated jets to ensure the fuel flow was identical with each different ratio, and warmed the engine at 3000 rpm for 3 minutes before each run. Our tests were performed in the rpm range of 2500 to 9000 rpm, with the power peak of our test bike (an '86 YZ 250) occuring at 8750 rpm. We tested at 76 degrees F, at 65% relative humidity. We started at 10:1, and went to 100:1. Our results showed that a two-stroke engine makes its best power at 18:1. Any more oil than that, and the engine ran poorly, because we didn't have any jets rich enough to compensate for that much oil in the fuel. The power loss from 18:1 to 32:1 was approximately 2 percent. The loss from 18:1 to 50:1 was nearly 9 percent. On a modern 250, that can be as much as 4 horsepower. The loss from 18:1 to 100:1 was nearly 18 percent. The reason for the difference in output is simple. More oil provides a better seal between the ring and the cylinder wall.

Now, I realize that 18:1 is impractical unless you ride your engine all-out, keeping it pinned at all times. But running reasonable ratios no less than 32:1 will produce more power, and give your engine better protection, thus making it perform better for longer.

The bottom line? Choose a mix ratio that is adequate for your needs, and jet accordingly. You don't fix plug fouling and spooge by adjusting your mix ratio.[/color

This is an interesting read that also supports my "more oil is better" claim.

http://www.bridgestonemotorcycle.com...oilpremix6.pdf

And this is a good article as well:

http://www.maximausa.com/technical/l...summer2001.pdf


Offline ford832

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Re: Oil and ratios
« Reply #25 on: February 20, 2010, 05:48:22 AM »
I

My experience has been that lower rod end bearings fail first from a lack of 2T oil.



[/b]
[/quote]


Exactly so.In my case though,I'm 40:1 for tight slow woods races/rides and between 25/30:1 for track use or more wide open running.
I'd rather a full bottle in front of me than a full frontal lobotomy.

Offline xxzertox

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Re: Oil and ratios
« Reply #26 on: May 22, 2011, 02:13:10 PM »
Thank you very much.