Thanks for the replies.
Is member 221 an authority on oil ratios, suspension mods, fuel rules, or all three?
I found this in the GCRs:
Leaded fuel provided that the fuel is purchased from suppliers approved by Environmental Australia.
My Avgas question stands...
80:1 sounds lean, but I understand as the capacity goes up the revs and oil required goes down - common belief at least.
Some good looking info from, of all places, "Perth Street Bikes" (and probably on this forum somewhere.)
Guys this is the best answer I have seen on oil ratios and types, in short 25:1 for nearly all oil except MC1+ or the top of the range Motul, running the other oils leaner just wears engine parts. Enjoy.
Dispelling the mystery between BR MC1 and other 2T oils
Viscosity of Motul 800 and other 2T oils
2 stroke fuel mixture
(I posted this topic on another forum that created a lot of interest and it was suggested by some that I post it here for the benefit of a larger audience of riders who may get a better understanding of what things are all about. I was not happy about that article that appeared in one of the recent VMX issues so I wanted to offer an alternate view to readers from a different perspective.............in this article below I also do not commercially represent any oil brands whatsoever and have no preference for a particular brand, but have had the benefit of working into the lubricants industry in a marketing & technical capacity for 23 years and ridden/worked on both on and offroad motorcycles for over 30 years )
"I wanted to wait till I got all my data on hand to sort out the issue relating to oil mix ratios with certain 2T oils on the market.
As Leith said that in many magazine tests from the early 80's testers ran the bikes on 50:1 with Bel-Ray (BR) MC-1.................now that is OK from a lubrication point of view with that grade as i will explain later, but not without risks.
But the public should have been informed why this is so.............and it is nothing really to do with any high tech advancement of the product by BR. Perhaps the company thought the motorcycle riding fraternity would not comprehend some figures (And when i look back at myself way back then and some of the people i rode with they may be right). Do they really look at us as just a bunch of illiterates?
Many riders were also running 100:1 in their bikes in MX and as of still today a famous Australian stunt rider who still rides early RM500's to my knowledge still uses MC-1 at 100:1 with success with no rebuilds for 10 years.
There doesnt seem to be much debate (not that i I know of or can see in any other forums) about an article written by a representative of Bel-Ray Oil Co in one of the latest VMX issues. It appears that again the reader has taken as gospel what has been written by a "marketing" person not a technical or engineering person who can explain to the reader why this is possible to run ratios around say 50:1. Even though the VMX article does not mention using ratios as lean as 100:1 I feel that much of what has been written is totally inaccurate and irrelavent for pre 90 VMX machinery and for a certain amount of time I was thinking on not renewing my subscription so upset I was that something like that could be published. And as a consequence of that article the reader may have leaned off his oil mixture much to the detriment of his bikes engine.
Happily I have since discussed and am continuing to have dialogue directly with VMX magazine over my alternative viewpoint about really one of the most talked about and debated issues in motorcycling perhaps equal with tyre choice, jetting and the like.
I wrote to BR is the USA in the form of an inquiry to ask about the specifications of their variuos 2T oils as "I was tuning some engines and wanted to scientifically calculate specific gravities (densities) of fuel mixes with variuos oil ratios"....................
A helpful response was sent to me overnight including Material Safety Data Sheets (MSDS's) that contain the figures that I asked for to help me explain what I needed. And sure enough as soon as I opened up the MSDS's it hit me right away and the cover of all the hype & BS over the years that BR has been dishing out was exposed.
Superb products.......all of them.......absolutely!!.............up there with the best...............but how nice it would have been if BR described their rationale to riders 30 years ago when their product was launched why their product was suitable at 100:1. Today it has realistically been recommended to run 50:1.
The reason as a marketer and engineer in this industry I can tell you, was too make the market believe that BR has miraculously bought into some extraterrestial technology that no one else has managed to come across. And it worked for them in selling millions of gallons of the stuff over the last 3 decades.
There is no big secret..............it is all in plain black and white on the MSDS's................MC-1 has a viscosity of 235 Centistokes (Cst) @ 40c (100F) which equates to about an SAE50 or gear oil SAE90 thickness. On the other hand their other synthetic products are less than a quarter (a fifth or 20% of the thickness) of MC-1.........between 40-50 Cst @ 40c (SAE10W-20 or gear oil of SAE 80W).
As an illustration, I used to use Castrol Biolube 100 in my performance outboards at 100:1 and they ran OK, noisy compared to 30:1 (due to less oil cushioning metal parts) which I run now and HP is way up including throttle response (due to better sealing and compression), but they didnt blow up as Biolube is about the same viscosity as MC-1 so a thick film of oil was present.
People who follow manufacturers recommendations (Which are another marketing ploy to offer false savings in running costs and to pander to environmentalists) and run normal prediluted TCW-3 oils at those lean ratios would definatley reduce the life of their motors and not achieve the full HP rating of what they purchased.
The plain jane mineral oil (S2) is about 100Cst in the MSDS which is normal as being mineral you need a heavier base fluid with some bright stock, or some heavy esters in its place at around 25%, to create film thickness for lubricating your engine. You get what you pay for in some cases.
So the simple science behind this is when you cut back (dilute) a heavy oil such as MC-1 (ie: like thinning down a thick grease) with fuel to make your premix of course it is going to lubricate your engine well at 100:1 without seizing it as the end viscosity of the oil in the fuel mix is still thick enough to form a film of oil on the parts........and it wont change the density of the fuel mix affecting your jetting requirements too much, however there will still be MORE fuel in the mix requiring a leaning of your mixture but NOT due to a change in density (or net fuel viscosity) that affects the passage of fuel through the jets in a given time...............where if you dilute their Si-7 oil which has been made with lighter Esters of between 40-50 Cst at 100:1............well bye bye engine..............little or no film thickness there at that ratio and hello engine rebuild and track side seizure.
Even BR themselves as you can see below in their statement to me now recommend not to use MC-1 at ratios leaner than 50:1 which surprised me as I remember all the hooha in the 80's about 100:1 and MC-1. HALF of what they promoted in the past. Too many eggheads seizing their bikes.
In the Suzuki PE owners manual it lists oils such as Castrol R40 which is 150Cst @40c (an SAE 40, SAE 85W gear oil viscosity to assist the layman reading this to comprehend what i am explaining, hopefully) mixed at 20:1 which when you examine things closer would provide very good lubication in the engine of a relatively thick oil at rich ratios. Hence this can explain the very good power figures when the tester held the throttle wide open and measured HP in that famous Oil ratio article by Gordon Jennings in Feb 1978 that found more oil is better.
But R40 being a castor oil at 20:1 was also found to produce high deposits but for race engines it was immaterial as the motor was stripped often, and also ridden flat out preventing much of these deposits from occuring in the first place. Perhaps R40 at 20:1 was overkill to some extent for the average trailrider who would have expereinced plug fowling, ring sticking and exhaust deposits.
So to summarise the mechanics of what this means............be careful what you buy and what ratio you mix it in.................for example MC-1at 20:1 would be great if you rode fairly hard all the time like wide open throttle desert racing but at slower woods type, or frequent slow to fast and slow again riding you would potentially oil everything up as the thick base oil would coat plugs and well up inside your chamber as it wouldnt flow or atomise adequately, you would have to really mix the fuel well and not keep it for long. It would make the bike hard to start as you would be oiling plugs frequently, and it would separate quicker in the tank/float bowl when left sitting.
But the oil that i use which is 45CSt at 20:1 runs perfect at all speeds, and runs through the engine does its job and then goes out without hanging up in the exhaust or combustion chamber so that the engine can perform like a 2 stroke.
I think Motul 800, Castrol A747 are thick esters as well (See subsequent article that follows)...........and I have written before which is overkill at rich ratios for engines under 9,000RPM.
Perhaps some of the plug fowling I hear at Vinduro's is caused by improper jetting combined with these thick 2T oils at too rich mixtures.............something else I need to ask the riders. I talk to many riders and they tell what ratios they are running like 40-50:1 in their old bikes and then they complain about worn and seized crank pins, big ends and short ring life, detonation partially caused by overheating the engine from not enough oil in their fuel. More oil keeps your engine cleaner with less deposits as it acts as detergent/dispersant to constantly prevent deposits from adhering to your parts.
So riders out there mixing their light viscosity 2T oils (which are 95% of the oils sold such as Castrol TTS, Shell VSX2, Motul 710, Motrex etc) at lean ratios (>32:1) are shaving heaps of metal from their motors, creating blowby and further wear & deposits and loosing performance.
Is there any benefit in playing Russian Roulette with 100:1 even though the oil "may" be technically suitable. In my view "NO" one reason because you are adding what 200ml (about 7 Ounces for any USA readers) of oil into 20litres (5.28 USG) and the margin for error is too great unless you are using almost laboratory accuracy to combine and mix components. The heavier oil will also mix more slowly and in cold weather may either fall out of suspension or lead to oil starvation when starting as it may cling to cold crankcase surfaces and not enter the bearings and cylnder walls.
There is too high a risk that slugs of your fuel mix will have no oil in it, and to have heavier but fewer fractions of lube oil in your mix makes it too unpredicatable and unreliable in my books.
I look at some of the factory teams in MX over here who ran MC-1 at 100:1 in the late 70's and 80's. They had a team of mechanics who meticulously measured each componant and mixed it all thoroughly for a very long time to ensure the oil was dispersed throughout the mix. What proportion of trailriders/VMX'ers do that?
Does MC-1 lubricate and protect your engine at 40 or 50:1 better than say Castrol TTS at 20:1, I really doubt it, and there is really no advantage in going down that path.
You look at the PE greats like the Geoff Udys and Brian White (In Australia and I am sure the Americans could name riders from their own shores) who ran MC-1 @ 40:1 or less in their PE's and got away with it............do you think these great riders completely understood why it was working for them? I dont think so!! They would have believed that BR was a superior company in itself and sold a magical product. As is the case with most magic it was simply an illusion.
The "trendiness" and "coolness" factor in these lean ratios amongst a major group of riders is really just that, a fantasy fed by ones ego (and the greater dirtbike scene is overflowing with that.........no lean ratios of that there) that is being chased, created by some clever formulation chemists in conjunction with marketers over 3 decades ago when Polyol-Esters & PAO's began to take hold in the market. These fantasies have perhaps led to the reliability problems experienced by riders, not just in the pre-85 scene. And recent articles that have been written will only maintain this trend.
From my understanding there is very little benefit to your motors in running leaner oil ratios, especially with the lighter grade oils that most of us use. At 40:1 ratios (Even 32:1) riders are really deluding themselves and trying to either save some money or follow some trend that will only lead to shorter engine life while still thinking that everything is OK.
This is but a brief introduction to help offer an alternative viewpoint to a much discussed and to date people are potentially as misinformed and unable to make rationale oil ratio decisions as they have been,
So my advice is run around 25:1 -20:1 in your old aircooled mills (and many WC ones), jet your carb right to suit and then ride with a clear consciuos that enough oil is inside your engine................
Part 2 (Bellrays reply removed)
One myth, before I discuss oil ratios using these products, is the the case of "Anti-Smoke". Todays 2T oils will smoke, but no where near as bad as the technology flogged to riders from the 40's to the 70's in mineral oil formulations that contained Bright Stock, a heavy by product of oil refining that gave great lubricity and film strength but when subjected to the flame front inside a 2 stroke engine on its way out the exhaust it made very thick bad smoke and created hard crystalike deposits of carbon in their combustion chambers and exhaust systems..
I have said that oil marketers may percieve the riding public as uneducated fools of consumers (I have admitted that this may hold some water) so easy to spin a story on a label or advert and sell tanker loads of oil to them. Dont you just hate buying a 2T oil, mixing it up and running it in your bike and it still smokes??? I recall when I used Mobil Extra 2T semi synthetic when it first came out back in 1995 and it still smoked!! I thought who are they trying to fool here?
Mobil sunsequently changed the claim to "Low Smoke" and "this product will create less smoke than our mineral formulations".
Now that is a more accurate claim. On the Motul data sheet it says "Anti Smoke" that is an odious claim. Oils contain "Anti-Wear" additives such as Zinc, Molybdenum, Phosphorus etc that reduce wear, it does not stop wear, it slows down the wear rate that is all. In the buyers mind when he is looking at the bottle before he wanders to the checkout he thinks Oh great no more smoke!
Ok so with all the specifications of their major 2T oils, I can conclude that riders who use Motul 800 are wasting their money mixing it @ 20:1 or ratios less than say 40:1 as the maker states. This is because like Bel-Ray MC-1 that is much heavier still than 800 to mix it at rich ratios will create an amalgum of oil/fuel that will not ignite to its optimum level. At that ratio it will simply quench the flame.
Using heavy 2T oils at rich ratios will not alow the bike to operate properly by restricting the proper flow and atomisation of the fuel/oil mix to pass through the engine. This may neccesitate the use of larger pilot jets (as some riders have found).
Motul 800 would be ideal in later model bikes with powervalves and chrome or Nikasil type bores at ratios around 40:1 or leaner to 50:1. (Ideal oil to use in later model KTM 2 strokes etc) I would still run as much oil as I can get away with if I had a late model 2 stroker perhaps starting at 32:1 and work down towards 25:1).
For VMX's now running Motul 800 @ 20:1 save yourself some money in purchase price first off and switch to Motul 710 (or even 510 semi synthetic that is more than enough) at 20:1 and then experience your bike running better all round with better throttle response, cleaner spark plug, less oil hang up in the exhaust and crankcase, perhaps less thicker smoke. It should also lead to a greater wear reduction as the oil will migrate to the sliding surfaces better.
800 is 135 Cst and 710 is 50Cst, (remember dont run 710 at lean ratios......bye bye motor) much lighter by almost 2.5 times and better for rich ratios allowing the oil to lubricate the engine better, mix more thoroughly with fuel, with no hangup inside the engine. With 800 @ 20:1 the rider may face starting difficulties on a cold engine, or with old fuel (oil separation happens more with thicker oil falling out of suspension) or in cold weather.
I looked at the Motrex and ELF websites (Both make 1st class 2T oils) and only Motrex list a viscosity grade in SAE (SAE 20 or SAE 30) on their website. But if the rider doesn't know what this means or the implications of it (which 99.9% of them wouldnt know) then he cannot make an informed decision on what the best oil is for his bike. He relies on his mates advice while drinking around the campfire.
I believe in looking back at desert racing especially since the early 80's many of the engine failures and blow ups at wide open throttle running has been caused by lean oil ratios using both heavy and light grade 2T oils. I recall Jim Ellis's KTM MC500 in particular blowing up in the 1986 Alice to Finke race. It was blamed on metal fatigue (which is correct) but most probably caused by not enough oil in the fuel mix to lubricate the metal surfaces, keeping the temperatures low and metals from not expanding leading to parts contact resulting in metal fatigue in a nanosecond at 100MPH cracking & lifting his engine barrel of the cases putting an end to his ride. It is like saying someone died of cancer, but the cause was through excessive smoking.
So to summarise here, dont waste your hard earned on top shelf oils for your Pre 90 bikes or even later bikes (including 4 strokes), use mid tier synthetics of the lighter viscosity type or semi synthetics that are more than enough. Use more oil like 20:1 (like I use in my PE400 that runs crisp, hard and has clean carbon free internals) or 25:1 and see the difference in your bikes performance and engine life.
Long, but interesting
