Oil Mixture

[taffe]

I thought that the guy in the photo waiting to catch the chain when it broke should be wearing safety glasses.

[axulsuv]

"Hey Jon ; Isn't your brother supposed to be wearing safety Glasses ???"........No problem, he's a Lumberjack and he's o.k......

​He's a lumberjack and he's ok ... I vaguely remember that song ... ?

BAD A$$ SAW though , I did that up in Oregon , but not at that level , more of the stop the fire kinda thing ...

Glenn

[jse]

I don't know if we ever really answered buck's question. From my experience, most riders use a full-synthetic premix oil in ratios ranging from 60 to 100:1, so an 80:1 ratio is about in the middle and also seems to be the most popular.

A good rule is to try to mix a fresh batch (fresh oil and fresh gas) before each ride.

Jon

[axulsuv]

Except for the mixing it before each ride , I totally agree , I run all my old Fantics at 75 to 1 with no issues , but I also run ave gas bought in 5 gallons at a time , I like to mix larger quantities for better accuracy and the ave gas doesn't go south ...

And my memory just worked !!!! It's a old monty python skit/song !!!

Glenn

And I forgot to say that's with Amsoil's best synthetic premix oil ... ('just 'cause its red and matches my bike and doesn't get put in anything else by mistake ,,,(kids!) .

Edited December 26, 2013 by axulsuv

[dadof2]

Hi again, firstly a bit more on the ring failure I mentioned. The problem was not down to acceleration forces on the rings, it was due to the breakdown of the lubricant film between the ring and bore. The evidence suggests this was a lubrication rather than an engine material problem but it is not as clear cut as that. Once the lubricant film breaks down friction causes heat and the ring or bore expand more locally increasing the contact pressure and irreversibly damaging the ring and bore. The symptoms were that the engines would seem to loose power and once stopped would be difficult or impossible to restart. The problems occurred on engines using manufacturers recommended oil (fully synthetic) at the recommended ratio of 50:1. There were doubts about the fuel quality, the time it had been mixed and the accuracy with which the 50:1 had been consistently adhered to. Engines run on Texaco Motex 2T (a mineral oil) at 32:1 did not have any problems despite the oil not meeting the manufacturers specification, however in these cases it was known that the mix ratio was adhered to and the fuel was used within 24 hours of mixing maximum and that the fuel was Texaco or Gulf and used within 2 days of purchase.

I suggest having a look at http://www.rotaxservice.com/rotax_tips/rotax_feed2.htm which makes interesting reading for those using high mix ratios of fully synthetic oil in infrequently uses engines or where there is water about - both of which are common factors in trials bike usage.

Synthetics oils when used correctly do have very high film strength / anti seize properties and it it probably this coupled with a desire to reduce emission that has led to the adoption of high fuel to oil ratios. Modern engine materials are pretty good so generally these ratios work but that does not mean they give optimum performance or lubrication (engine protection)

Edited December 25, 2013 by dadof2

[jse]

Hi again, firstly a bit more on the ring failure I mentioned. The problem was not down to acceleration forces on the rings, it was due to the breakdown of the lubricant film between the ring and bore. The evidence suggests this was a lubrication rather than an engine material problem but it is not as clear cut as that. Once the lubricant film breaks down friction causes heat and the ring or bore expand more locally increasing the contact pressure and irreversibly damaging the ring and bore. The symptoms were that the engines would seem to loose power and once stopped would be difficult or impossible to restart. The problems occurred on engines using manufacturers recommended oil (fully synthetic) at the recommended ratio of 50:1. There were doubts about the fuel quality, the time it had been mixed and the accuracy with which the 50:1 had been consistently adhered to. Engines run on Texaco Motex 2T (a mineral oil) at 32:1 did not have any problems despite the oil not meeting the manufacturers specification, however in these cases it was known that the mix ratio was adhered to and the fuel was used within 24 hours of mixing maximum and that the fuel was Texaco or Gulf and used within 2 days of purchase.

I suggest having a look at http://www.rotaxserv...rotax_feed2.htm which makes interesting reading for those using high mix ratios of fully synthetic oil in infrequently uses engines or where there is water about - both of which are common factors in trials bike usage.

Synthetics oils when used correctly do have very high film strength / anti seize properties and it it probably this coupled with a desire to reduce emission that has led to the adoption of high fuel to oil ratios. Modern engine materials are pretty good so generally these ratios work but that does not mean they give optimum performance or lubrication (engine protection)

What ratio and mixing conditions do you recommend?

Jon

[copemech]

Hi again, firstly a bit more on the ring failure I mentioned. The problem was not down to acceleration forces on the rings, it was due to the breakdown of the lubricant film between the ring and bore. The evidence suggests this was a lubrication rather than an engine material problem but it is not as clear cut as that. Once the lubricant film breaks down friction causes heat and the ring or bore expand more locally increasing the contact pressure and irreversibly damaging the ring and bore. The symptoms were that the engines would seem to loose power and once stopped would be difficult or impossible to restart. The problems occurred on engines using manufacturers recommended oil (fully synthetic) at the recommended ratio of 50:1. There were doubts about the fuel quality, the time it had been mixed and the accuracy with which the 50:1 had been consistently adhered to. Engines run on Texaco Motex 2T (a mineral oil) at 32:1 did not have any problems despite the oil not meeting the manufacturers specification, however in these cases it was known that the mix ratio was adhered to and the fuel was used within 24 hours of mixing maximum and that the fuel was Texaco or Gulf and used within 2 days of purchase.

I suggest having a look at http://www.rotaxserv...rotax_feed2.htm which makes interesting reading for those using high mix ratios of fully synthetic oil in infrequently uses engines or where there is water about - both of which are common factors in trials bike usage.

Synthetics oils when used correctly do have very high film strength / anti seize properties and it it probably this coupled with a desire to reduce emission that has led to the adoption of high fuel to oil ratios. Modern engine materials are pretty good so generally these ratios work but that does not mean they give optimum performance or lubrication (engine protection)

Not having read your reference, I might assume this still required some hard running as compared to an average putt-putt trials bike. I do believe that many Mfg. recommendations are quite on the conservative side out of necessity and due to unknown factors such as mineral, semi or full synthetic.

Seems some still swear by the semi, and as far as I know, the Yamaha 2T Racing is still popular and the same(made) as Torco brand(rebranded). It works and I have used it without issue.

Honestly, I consider myself conservative on oil issues, as there are a ton of companies pushing their product, and most at premium price for 2T racing. I think much of this is marketing, and I have no way of knowing which is best, so must rely on track records it seems. And therefore, I have mostly stuck with the Maxima product here based upon near 15 years track record of our Sherco importer, and at the same 80:1 ratio as used by our team riders.

I have run them hard, really hard, without issue. Not sure I am comfortable with our fuel at 10% alcohol, with water included.

In the automotive world, I am still conservative, motto here is best oil is clean oil. We have cars running 200K miles and more on mineral oil, is it really worth the added cost for synthetic, and mostly no increase in change interval? I am not sure, as it is prolly good oil but?

[guys]

I once followed a training on oils given by a representative from Texaco. He told us there's no need to use full synthetic oil (if it's not prescribed by the car manufacturer).

Semi-synthetic is more than good enough for normal use.

I must say this was about 10 eyars ago, but at that time, even the formula one team that used their oil, used semi-synthetic oil...

[trialsuk123]

can anyone help me of the oil ratio of 2 stroke oil to go to 5 litres of fuel in millemetres

[guys]

can anyone help me of the oil ratio of 2 stroke oil to go to 5 litres of fuel in millemetres

http://www.csgnetwork.com/oilfuelcalc.html

[0007]

Dadof2, just avoid quoting the entire post

Thanks for the info, engine testing is very interesting stuff, do you do this kind of work?

I like to see how and why things happen in engines, amazing how subtle changes make radically different results

Q: for curiosity reasons, were the engines air cooled? (Chainsaw)

On a waterbrake dyno (rpm controlled by load or electronically limited)

Was there any detonation (detonation applies shock wave loads to rings, damaging ring land etc etc)

I remember reading about Jeremy McGraths Honda CR from 2004 era and they were running 24:1 if I remember correctly but that engine was somewhere in the neighborhood of 70hp and run about as hard as an engine could be run, these factory engine builders are full of secrets so there is no way to know what makes an engine like that survive at that power level

[copemech]

Dadof2, just avoid quoting the entire post

Thanks for the info, engine testing is very interesting stuff, do you do this kind of work?

I like to see how and why things happen in engines, amazing how subtle changes make radically different results

Q: for curiosity reasons, were the engines air cooled? (Chainsaw)

On a waterbrake dyno (rpm controlled by load or electronically limited)

Was there any detonation (detonation applies shock wave loads to rings, damaging ring land etc etc)

I remember reading about Jeremy McGraths Honda CR from 2004 era and they were running 24:1 if I remember correctly but that engine was somewhere in the neighborhood of 70hp and run about as hard as an engine could be run, these factory engine builders are full of secrets so there is no way to know what makes an engine like that survive at that power level

Having now read Dadof2's ref article, this reminds me why I do not like 2T aircraft at any ratio! This stuff is ugly enough on the ground, god knows I have had a few bad experiences at speed!

[lewis cosgrove]

[jse]

Dadof2, just avoid quoting the entire post

Thanks for the info, engine testing is very interesting stuff, do you do this kind of work?

I like to see how and why things happen in engines, amazing how subtle changes make radically different results

Q: for curiosity reasons, were the engines air cooled? (Chainsaw)

On a waterbrake dyno (rpm controlled by load or electronically limited)

Was there any detonation (detonation applies shock wave loads to rings, damaging ring land etc etc)

I remember reading about Jeremy McGraths Honda CR from 2004 era and they were running 24:1 if I remember correctly but that engine was somewhere in the neighborhood of 70hp and run about as hard as an engine could be run, these factory engine builders are full of secrets so there is no way to know what makes an engine like that survive at that power level

You've touched on a problem area that we are dealing with. Two-stroke engines are used in a wide variety of ways and I don't think you can extrapolate "correct" ratios without knowing the operating conditions and engine design parameters, to do so is comparing apples and oranges.

The 2T aircraft engine mentioned sounds like an ultralight type two cylinder. This is a relatively constant lower RPM use, reasonably long operating time, constant soft load with a trend towards overcooling. It is difficult to compare it to McGrath's CR engine which is relatively short duration operating time, liquid-cooled, wide open/trailing throttle, heavy load, frequent over run RPM etc. AND, you would need to know if that was his outdoor or Supercross engine, trust me, they are very different animals, having built both types. Another interesting twist is that Honda usually sets their production MX 2T bikes to a 20:1 premix ratio (first thing a rider would do with a Honda is change to 32:1 and drop the main jet 3 points) so the factory engineers were, in actuality, leaning out the ratio for a full-on race bike as compared to a standard production bike.

Based on general use over a number of years (time-based experiential data), I think we can safely assume that a ratio in the area of 80:1 seems to work well for the average Trials rider running a liquid-cooled engine and that a rider should also take into consideration any unusual conditions that would dictate adjusting that ratio. Because of the wide variables involved, the "perfect ratio" is ever elusive and may, in fact, be non-existent, or only exist for a snapshot in time for a specific engine running under specific conditions. When building a racing engine (or choosing a premix ratio), the race tuner is constantly compromising and making a balanced decision between performance and reliability and I think it behooves any rider dealing with this issue to do the same.

Although this horse has been dead for a very long time, we do enjoy giving it a couple more whacks now and then, just for fun.....

Jon

[b40rt]

FIO - twin cylinder 2 stroke rotax microlights in UK generally run at 50:1 and are so over cooled that 80% of radiator is covered in winter.

Edited December 27, 2013 by b40rt