fuel/oil ratios

[jaguar57]

After ruining a steel cylinder using a supposed synthetic oil mixed at 25:1 I decided to fully read up on the subject to be better informed on this subject. Here is my page with what I found out: http://www.dragonfly75.com/motorbike/oil.html

[adam728]

Want to go further down the rabbit hole? Start researching ISO-EGD, JASO-FD, API-TC, etc.

[CDNSXV]

25:1 is way too much oil, which caused air-fuel mixture to lean out, which is likely what damaged your engine.  40-50:1 is what most bikes would run.

[SDet]

1 hour ago, CDNSXV said:

25:1 is way too much oil, which caused air-fuel mixture to lean out, which is likely what damaged your engine.  40-50:1 is what most bikes would run.

You could play with jetting to run 10:1 if you wanted to. And honestly, you're going from 98% fuel to 94%. So if you were at 14:1, you'd be at 14.3:1. Not a huge change, and with a carb, you'd likely only have one lean spot in the whole rev range. 

 

If you don't want to play with jetting, run what the factory says. That said, I question some of that web page, but I'm not well researched enough to dig into it. 

[mlatour]

If you prematurely wore a cylinder using 25:1 of any quality brand premix,

I'd suspect many other things before the oil or premix ratio.

Metallurgy, machining/assembly error, out-of-spec/alignment issues etc. etc.

 

With the wrong jetting, bad fuel or an air leak,

no doubt an engine could seize with using any oil or ratio, moreso if it's used in a racing context.

 

That being said, at 25:1 more oil means less fuel per volume so richer jetting is required.

Oil lubes the bearings but fuel cools engine internals and prevents the piston from expanding into the bore.

Edited July 17, 2017 by mlatour

[ossagp]

On 7/14/2017 at 11:05 AM, jaguar57 said:

After ruining a steel cylinder using a supposed synthetic oil mixed at 25:1 I decided to fully read up on the subject to be better informed on this subject. Here is my page with what I found out: http://www.dragonfly75.com/motorbike/oil.html

How long did you run your rig to "ruin" the cylinder?   

[ossagp]

On 7/16/2017 at 8:21 PM, mlatour said:

If you prematurely wore a cylinder using 25:1 of any quality brand premix,

I'd suspect many other things before the oil or premix ratio.

Metallurgy, machining/assembly error, out-of-spec/alignment issues etc. etc.

 

With the wrong jetting, bad fuel or an air leak,

no doubt an engine could seize with using any oil or ratio, moreso if it's used in a racing context.

 

That being said, at 25:1 more oil means less fuel per volume so richer jetting is required.

Oil lubes the bearings but fuel cools engine internals and prevents the piston from expanding into the bore.

Maybe in my next 50 years of playing with these critters I will find an engine that actually seized because  the operator was running too much oil.  

[jaguar57]

CDNSXV, you are thinking of ratios for high quality fully synthetic oils. SynPlus, the one from Amalie that I used, I now believe has very little synthetic oil in it as it smokes considerably, just a little less than regular oil.

SDet, its jetting was very slightly on the lean side, enough to cause a little blackness on the underside of the piston. So that is a factor. But something else happened that I didn’t tell yet. The crank bearings are now making a metallic noise. The bike is only 3 years old. So the oil was insufficient at lubricating the bearings as well as the cylinder.

mlatour, what I believe is that SynPlus is a very low quality oil. I used it because down here I couldn’t find any better oil and I thought I couldn’t import any from the States. I now know that the mail forwarding service I use allows shipping one bottle of oil at a time so I have just ordered Motul 800 synthetic oil as well as the low end bearings and seals.

ossagp, this is my daily street ride. When it gets up to high revs it usually isn’t for a long time.

 

HERE'S snippets of info on the net I gathered the other day, mostly about synthetic oils:

Three Different "Types" of Oil

There are basically three different types of oil available. We have straight mineral based oils, straight synthetic oils, and then we have something called a semi-synthetic. The semi-synthetic oil is a blend of both mineral and synthetic oils.

Mineral based oils are generally known for good lubrication properties while the engine is running and then, while the engine is sitting between flights, the mineral oils do a great job of keeping the internal parts of the engine coated with a fine film that keeps rust from forming. However, there have been complaints about excessive carbon deposits and stuck rings in some cases when straight mineral-based oils are used.

Synthetic oils are generally known for having excellent lubrication properties with low deposits while the engine is running. But, the super slick nature of straight synthetics has been accused of not being very good at leaving the fine film on the internal parts while the engine is inactive. The semi-synthetics are touted as being the best of both worlds by providing the pro's and limiting the con's of both the mineral and synthetic oils.
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First, let’s define “synthetic.” If it sounds high-tech or advanced, it’s because it is. 

Where traditional mineral or conventional use refined crude oil (that stuff you find in the ground), synthetic oils consist of chemical compounds that are artificially made by breaking down and then rebuilding petroleum molecules. The end result is an oil containing specific molecules that are tailored to provide optimal lubrication properties. 

There are different types of synthetic oil: synthetic blend oil and full synthetic oil. Here’s the difference. 

Synthetic blend oil is a mix of conventional motor oils and synthetic base stocks. Because of the added synthetic base stock, you’re going to get more performance and protection than you would by using a conventional oil alone. 

Full synthetic oil uses a synthetic base stock mixed with a variety of additives that boost the performance of the oil. While all synthetics on the market may offer a higher level of protection than conventional or synthetics blends, not all synthetics are equal. Each synthetic brand uses a mix of high-performance fluids and additives. How these formulations come together results in various protection levels and attributes.

https://mobiloil.com/en/article/car-maintenance/learn-about-motor-oil-facts/types-of-synthetic-oil
- - - -
DATA ON DIFFERENT SYNTHETIC OILS

Maxima Super M
<60% Trimethylolpropane tricaprylate/tricaprate (Molecular Formula C30 H56 O6) - classified as SKIN CONDITIONING EMOLLIENT
Formulations containing TRIMETHYLOLPROPANE TRICAPRYLATE/TRICAPRATE:
Formulation-Toiletries: Anti-Whitening Solid Antiperspirant. This solid antiperspirant has a nice glide, does not leave white residue on the skin, and controls perspiration and odor.
Formulation-Hair Care: Hair Polisher Spray. Trimethylolpropane Tricaprylate/Tricaprate should provide a lasting shine and radiance.

20-30% synthetic base oils
5-15% proprietary additives

12.3 viscosity @ 100C
- - - -
Amalie SynPlus Oil
7 viscosity @100C
42 viscosity @ 40C
190C flash point
- - - -
BalRay 
MC-1 Synthetic
no data

SI-7 Synthetic
26% petroleum distillates
no viscosity data
- - - -
Motorex Cross Power Full Synthetic
no data
- - - -
Bel-Ray® SL-2 Semi-Synthetic 2T Engine Oil
30-40% petroleum distillates
viscosity 41 @ 40C
- - - -
Maxima Super M $12.44/liter
<60% Trimethylolpropane tricaprylate/tricaprate
20-30% synthetic base oils
5-15% proprietary additives
12.3 viscosity @ 100C
- - - -
Golden Spectro Motorcycle Pre-mix $26.65/liter
12.8 viscosity @ 100C
102 viscosity @ 40C
77C flash point
42:1 to 50:1 recommended
TC rating
- - - -
Maxima FORMULA K-2 $16.59/liter
K-2 is a 100% synthetic 2-stroke oil utilizing 2000 centistoke esters along with special additives to achieve outstanding levels of protection and cleanliness. 
13.6 viscosity @ 100C
97 viscosity @ 40C
116C flash point
- - —
Maxima CASTOR 927 $18.18/liter (two 16oz)
927 is a unique blend of highly refined castor oil, a specially prepared synthetic and an additive system that reduces carbon and gum formation and provides excellent rust & corrosion protection. 
15.2 viscosity @100C
155 viscosity @ 40C
218C flash point
- - - -
Motul 800 Synthetic $17.54/liter
15.5 mm2/s viscosity @ 100C
120 mm2/s viscosity @40C
252C flash point
50:1 ratio recommended
TC rating
- - - -
Red Line Two Stroke Racing Oil $21/liter
42 mm2/s viscosity @ 100C
191 mm2/s @ 40C
105C flash point
50:1 to 100:1 recommended
exceeds TC-W3 rating
- - - -
Seems there are wide variations between the different oils. For instance Maxima formula K-2 is said to have 100% synthetic oil (maybe not) but their Super M has only 20-30% synthetic. I just ruined my Suzuki 100cc cylinder (wore it down quickly) using Amalie SynPlus, a supposed semi-synthetic, at 25:1. Turns out it only has a viscosity of 7 mm2/s at 100 degrees Celsius. Here’s some much better viscosities:
Motul 800 - 15.5, Maxima Castor 927 - 15.2, Maxima Formula K-2 - 13.6
So if Motul 800 is mixed at the recommended 50:1 then that gives the gas/oil a viscosity of .31, and the Amalie mixed at 25:1 a viscosity of .28 which are close but I don’t think Amalie has much true synthetic oils since it still has considerable smoke. Of course film strength is only one factor to consider. Some synthetics have additives that cause the oil to be slicker.

Supposedly the higher the engines RPM the more oil it needs so the gas to oil ratio has to be less. My Suzuki revs to 9500 RPM. 

I need to find info on how much more oil is needed for steel sleeve cylinders which is what my Suzuki has. Cylinders which are chromed are slicker and need less oil.
- - - -
TC (two cycle, air cooled) rating oil should be used at 25:1 (Stihl info)
- - - -
All cylinder liners (Sleeves) are about a class 40 grey Cast iron composition. Weather Spun cast investment or any kind of pour. The hardness can vary greatly depending on the kind of heat treating which was used. Steel is never used in cylinder liner composition.
- - -
for chromed/nikasil cylinders use oil with API-TC, JASO FD and ISO-L-EGD certification 
- - -
Two-cycle oils for water-cooled engines are labeled with a symbol from NMMA (National Marine Manufacturers Association) and are given the designation TC-W3.

The air-cooled category includes motorcycles, lawn mowers, generators, pumps, chainsaws and weed trimmers. Two-cycle, air-cooled engine oils are marked with just the API (American Petroleum Institute) TC designation.

"TC" stands for two-cycle, "W" means water-cooled and "3" designates the most current generation of two-cycle water-cooled oils.

For two-cycle oils identified as TC-W3, NMMA licenses a supplier based on data submitted from test procedures. For oils labeled TC, claims are made based on guidelines defined by API. For oils that do not carry either of these designations, you have only the claims made on the container or accompanying literature. In short, products without these designations are not monitored or approved two-cycle products under NMMA or API for entry into the marketplace. Therefore, consider trusting a supplier brand of proven performance when making a decision to buy.
- - - -
API TC is a certification for two-stroke oils, awarded by the American Petroleum Institute. It is given after the product passes through stringent tests that determine the level of detergent performance, dispersion, and anti-oxidation. It is the only remaining, not revoked classification of the API Two-Cycle motor oil specifications (TA, TB, TC, TD). Being a very old standard itself, most currently produced 2T lubricants meet its specifications, even the lowest quality ones; current high-quality oils exceed them (often labeled "API TC+" although not based on actual measurements).

The more current JASO_M345 or the international ISO two-cycle oil specifications are much better indicators of oil quality, with requirements based on modern two-stroke engines and environmental policies.
- - - -
Use semi-synthetic oil with ethanol blended fuels.

Semi-synthetic and 100% synthetic oils must meet the JASO FD specifications.  Here are some examples of oils available in the U.S. that state they meet this rating;  Castrol, Lucas, Motul, Amsoil SABER.

1. 100% synthetic 2 stroke oil: Amsoil SABER; Bel-ray Si-7 Synthetic 2-Stroke Engine Oil; Castrol Power RS TTS 2T (best buy, available online); Fuchs Silkolene Comp 2 Plus Pro 100% synthetic; Motul 710 2T; Motorex Cross Power 2-T; Red Line 2 Stroke Racing Oil; Shell Advance Ultra 2; Valvoline 2-Stroke Racing Oil

2. Semi-synthetic 2 stroke oil: Bel-Ray SL-2 Semi-Synthetic 2T Engine Oil; Fuchs Silkolene Comp 2 ester based semi synthetic; Lucas Semi-Synthetic 2-Cycle Oil; Motul 510 2T; Shell Advance VSX 2; Spectro Golden 2T Injector; SynGard  Use semi-synthetic 2 stroke oil with ethanol gasoline blends (see below).

Gasoline that contains ethanol should only be purchased from a major company, like ESSO, BP, Chevron or Shell, because their fuels contain important additives, especially detergents, that lessen the buildup of carbon inside the cylinder and gunk in the fuel system caused by the presence of ethanol.

To find sources of ethanol free fuel, go to this site -> http://pure-gas.org

A possible downside to 100% synthetic oil is that it tends to slip off metal surfaces during storage because of its super slippery nature.  This can result in rust forming on those surfaces. 
- - - -
Higher RPM engines and those operating at high cylinder head temperatures require more oil in the fuel to maintain proper lubrication.

The Red Line Two- Stroke Racing Oil is used at mixtures of 24:1 to 32:1 for 9,500 rpm outboard race motors.

Red Line Two-Stroke Racing Oil generally should not be used to seat a new ring because of the extreme slipperiness of the lubricant. A petroleum two-cycle lubricant used at normal loads for 15 minutes should be adequate for ring seating. Red Line Two-Stroke Oils can be used for ring seat if the engine is operated at 80% load for 15 minutes immediately after start up.

https://www.redlineoil.com/content/files/tech/Two-Stroke Technical Info.pdf
- - - -
BalRay:
The film strength is one of the more important properties of a 2-stroke oil. It needs to withstand the heat and combustion of the fuel without burning and also needs to be able to clean the parts that may have carbon deposits or gummy residues left over from poor combustion or less effective lubricants. Since the thin film of lubricant is the only thing to stop the piston rings from grinding into the cylinder walls, these lubricants must be capable of protecting against high levels of pressure during the stroke of the piston.

Certain 2-stroke lubricants are diluted with solvents to make them “clean burning” and provide “deposit control.” This is usually done to compensate for the lack of performance in the base fluid used. Since solvents tend to be highly flammable, the presence of them in the oil will also alter the combustion within the chamber. These solvents will alter the octane of the fuel and act as an impurity, causing detonation. Engines are designed to combust fuel, not the fuel and the extra flammables you’ll find in low quality lubricant products. The added combustion of part of the lubricant can result in a poor running engine or even engine failure.

For the greatest balance of performance and protection, a fully synthetic 100% ester based lubricant is the best choice for a modern 2-cycle engine. This 100% synthetic ester base fluid gives a high level of detergency to ensure the elimination of carbon deposits and deter the formation of new performance-robbing deposits.

Ester based fluids will withstand great amounts of heat and will not burn in the combustion chamber. Since they do not burn, the emissions are clear of soot and ash that are commonly found when using lower grade lubricants. These esters naturally adhere to metal surfaces and create a very tenacious film, so when the lubricant is brought onto the piston, it creates a film and spreads along the surface to protect the entire component. This film is difficult to eliminate, therefore, the engine will remain lubricated through very harsh conditions.

[adam728]

SynPlus meets JASO-FD. So it's likely not as crappy as you think.


Known lean jetting
Daily street ride for 3 years
Spins to 9500 rpm (not a big deal)
Black underside of piston crown
Noisy bearings



Sounds like it experienced some detonation and/or is just plain worn out.
How many hours on it?
What is a typical expected life span for that model?
What mods?
Been monkeying with ignition timing?

I'm with others in "it's probably not from the oil" camp.

[jaguar57]

It has 20,000 km. the bike is 3 years old. This original cylinder was bored out a few months ago for a piston made for a GP100 with .05mm skirt clearance. The GP100 also has an iron cylinder sleeve so I don't think it's a mismatch of materials.

Engine compression: 135psi. No detonation. No hard use and no prolonged periods at top RPM.

What tells me its the oil is that the crank bearings are now making noise. This is way too soon if a good oil is used.

I'm thinking that viscosity is linked to film strength (which BelRay says is very important) and this SynPlus has one of the lowest viscosities there are. The good oils have twice as much.

I just looked on the list of Jaso and SynPlus isn't there. Is it guilty of falsely labeling its oil as exceeding JASO-FC? http://www.jalos.or.jp/onfile/pdf/2T_EV_LIST.pdf

Edited July 22, 2017 by jaguar57

[skorpan777]

On 2017-07-17 at 5:07 AM, SDet said:

 

 

If you don't want to play with jetting, run what the factory says. That said, I question some of that web page, but I'm not well researched enough to dig into it. 

Yeah, I question some of the info in page.

Especially the comparison of mineral oil VS synthetic oil. It could be true 25years ago

Edited July 28, 2017 by skorpan777

[jaguar57]

Questioning is good. Trust no one but listen to everyone.

I've tried to get all the pertinent info I could find onto that page. As for me, I'm pretty convinced that the final viscosity after it is mixed with gasoline is the most important factor when determining fuel/oil ratio. If I had know this I would of been using SynPlus at 23:1 instead of 25:1. But since it isn't a true synthetic it should probably be used at 20:1.

I just replaced the main crank bearings and seals and could feel a little roughness when manually rolling the old bearings. I could feel that roughness while riding before I took it apart. Now it is smooth. Also all the parts exposed to the fuel/oil were coated black. I haven't split enough motorcycle cases to know how abnormal that is. But I feel that's not right.

Edited July 30, 2017 by jaguar57

[jaguar57]

SynPlus has a viscosity of 7 mm2/s at 100 degrees Celsius. Here's some much better viscosities: Red Line Two Stroke Racing Oil - 42 mm2/s viscosity @ 100C, Motul 800 - 15.5, Maxima Castor 927 - 15.2, Maxima Formula K-2 - 13.6
So if Motul 800 is mixed at the recommended 50:1 then that gives the gas/oil a viscosity of .31, and the Amalie mixed at 25:1 a viscosity of .28 which are close but I don't think Amalie has much true synthetic oils. Of course film strength is only one factor to consider. Some synthetics have additives that cause the oil to be slicker.

Viscosity is very important because it affects the oil's ability to reduce friction and transfer heat.
http://www.oilspecifications.org/articles/what-is-viscosity.php

Supposedly the higher the engines RPM the more oil it needs so the gas to oil ratio has to be less. My Suzuki revs to 9500 RPM.

from http://www.aijiuyujia.com/best-2-stroke-motorcycle-oil.pdf
An oils first line of defense is its viscosity (thickness). The ability of the oil film to prevent contact between the rings and the cylinder is a function of an oils viscosity. Generally speaking, the more viscous or thicker an oil, the greater load it will carry.

Keep in mind that a 4 stroke does not mix the oil with the gasoline and so the viscosity rating is "what you see is what you get". But a 2 stroke mixes the two and the ratio of the mixture affects the resulting overall viscosity. So if you want to maintain a viscosity of .3 of the gasoline/oil mixture then these are the fuel/oil ratios to use:
23:1 Amalie SynPlus
43:1 Golden Spectro
30:1 Bel-Ray Mineral 2 Stroke Oil (assuming a viscosity of 9 @ 100C*)
41:1 Maxima Super M
45:1 Maxima Formula K-2
140:1 Red Line Two Stroke Racing Oil
21:1 Bel-Ray SL-2 (assuming a viscosity of 6 @ 100C)
51:1 Maxima Castor 927
52:1 Motul 800

* for those oils that only list their viscosity at 40 degrees Celsius I derived an average viscosity ratio from 100 degrees to 40 degrees and applied that to come up with a "probable" viscosity @ 100C

Edited July 30, 2017 by jaguar57

[adam728]

Viscosity is one thing, having enough oil in the correct places is another. In extreme conditions (say SuperMinis it chainsaws) I'd take Bel-Ray SL-2 @ 21:1 over Redline at 140:1.

That is interesting that Amalie claims JASO but isn't on the list.

When you say all the parts exposed to fuel/oil were black, right from the carb on thru? Ports? Underside of piston? Reeds (if it has them)?

[jaguar57]

the crank and the cases around it were coated. not so the intake tract between reed and cases, probably because that is a "cooler" area.

I am thinking the oils that aren't full synthetics should have a higher final viscosity, say around .35 although really the semi-synthetics should be somewhere between .3 and .35 but without knowing what percentage of synthetic they have it is impossible to be specific.

So for a final 100C viscosity of .3 for full synthetics or .35 for others then these are the fuel/oil ratios to use:
20:1 Amalie SynPlus 
37:1 Golden Spectro 
26:1 Bel-Ray Mineral 2 Stroke Oil (assuming a viscosity of 9 @ 100C)
35:1 Maxima Super M 
45:1 Maxima Formula K-2 
140:1 Red Line Two Stroke Racing Oil 
17:1 Bel-Ray SL-2 (assuming a viscosity of 6 @ 100C)
43:1 Maxima Castor 927 
52:1 Motul 800

I had to assume a 100C viscosity for two of these oils because they only listed the 40C viscosity. I multiplied that viscosity by a factor I derived by averaging the ratio of a few other oils between their 40C and 100C viscosity. Of course the true 100C viscosity can be higher or lower than what I've assumed but there's nothing else I can do other than wait for the manufacturer to share full details.

I think it's pretty damn pathetic that the manufacturers have mostly let the populace shoot in the dark as far as ratios go. I see a label saying to mix between 20:1 and 50:1 without any guidance at all and I think "what is wrong with these people?". Only Motul 800 made a specific recommendation for ratio (50:1).

[jaguar57]

Going out on a limb even more...

A research paper used a 167cc 4 stroke engine with 6.6 compression ratio to record 250ºC at the piston edge @ 5000 RPM which could be projected to be 300ºC at 9000 RPM. The rings will be a little cooler since they are the thermal conduit between the piston and the cooler cylinder, and the cylinder is gradually cooler with distance down from its top. So if we guess at the average ring temperature as being 200ºC then we need to project for an engine oil viscosity at that temp for further comparison of oils. So for the oils that reveal their 40ºC and 100ºC viscosities I present this list which gives their predicted 200ºC viscosity and the final mixed viscosity (far right column). The higher the final number, the more protection for the rings and cylinder at high RPM.
 

[jaguar57]

I'm now thinking the problem of the engine wearing down had more to do with using 25% ethanol gas (although jetted for it) with engine oil that wasn't designed to be compatible with ethanol. Bel-Ray told me today that all their oils can be used with E15 gas but still that wouldn't of helped me since gas here is E25. I'm now manually removing the alcohol from the gas and I've rejetted for the new mix.

I just remembered that I had the same problem when I lived here 16 years ago and was racing a resleeved KDX200. The sleeve was wearing down quickly although I was using good oil that probably wasn't made to be used with so much alcohol. The good side of that story is that I got to try a different porting idea every 6 months when we resleeved it again. That was my trial-and-error introduction to porting. I was sure that the latino shop was just using cheap metal for the sleeve but I guess I was wrong. A 16 year mystery solved.

Edited August 2, 2017 by jaguar57

[skorpan777]

Keep it simple, buy a quality oil and stick with it and the more u use it you will find the right mix for you. 

If you read here you'll never get it sorted out, because EVERYONE has their on idea how you should do it

[Truman Sparks]

I Run Lucas TS oil at 20-1 in My IT465 (now 510cc), this is what Yamaha factory specs show to use.

I have be using 20-1 since way back when we were mixing regular motor oil for our  two strokes.

If I see a nice blue cloud I know my bike has plenty of oil keeping it nice and lubed up.

 

[jaguar57]

>"the more u use it you will find the right mix for you"

This is exactly the type of headache I want to avoid, and help others avoid. Trial and error sucks when the "error" means a premature dismantling of your engine.

Please, no more "this oil works good for me" anecdotes.

I approach 2 stroke technology as just that- technology. I like riding fast and crazy but when it comes to design topics I only like to approach from an engineers perspective.