Gas/oil ratio & types.

[Lloyd Boland]

OK, I admit it, I'm no petroleum engineer.  Can someone explain to me the difference between oils, for mixing with gas, and why the large difference in ratios?  I thought the oil was to lubricate the bearings and to keep the piston from seizing.  If that is the case, the more the better, no?  Isn't that why the old bikes used 20:1 or 24:1, and then with the water cooled bikes and better cooling and tolerences, less oil was needed.  I'm really confused because I understand you may also get more horsepower if you use a higher ratio but no-one wants to fry a motor.  Any input from the engine building experts out there?

[Rocket]

My take on oils and ratios, more oil is not always better.  The reason I think this way is because oil burns hotter that gas, gas actually acts as a coolant.  I would say, run any good oil at 40 or 50 to 1, and jet bike accordingly and you will have no problems.  I also believe that you should jet your bike a little richer breaking in a new motor, not more oil mixture.
Now this will probably bring about some controversy, but I have used Pennzoil outboard motor oil in my bikes for over 20 years, never had a seizure, very clean burning, power valves stay clean and piston, ringlife and bearing life has been great.
Rocket

[Lloyd Boland]

I'm breaking in a band new motor tomorrow and it was previously jetted with 24:1 and ran well.  If my thinking is right, if I go to 40:1 it will actually be richer because more fuel to oxygen molecule.  Is this right?  Should I just break it in tomorrow with what I know works (24:1) and worry about changing to 40:1 later?  I would like everyone's input as I think a lot of people may benefit from this discussion.  It has always been a little confusing to me.

[Lloyd Boland]

Rocket, thanks.  That information does help.

[OUCWBOY]

Someone here will know more about this than I do, but, I thought the reason there is a difference between the ratios now and then had to do with the difference in oils. Today, the oil is more concentrated than in the old days. Or at least that is what I was told when I got back into the dirt bike scene.

Donny Smith

[slvrbrdfxr]

Today's oils are so much better than what was available back in the 60-70's. I personally run a 40:1 mixture in all my bikes that take premix from my Pentons to my 2002 KDX200. My personal preference on oils is Polaris Premium Gold synthetic because it runs very clean and hardly any smoke. I even run this in my 86 Suzuki RG500 Gamma which has oil injection. I leaned out the oil injection on the Gamma a bit from stock setting and bike runs fine. Hope this helps.
Dave McC

[dirtbike]

No Rocket, there is no controversy at all!
Most 2-stroke oils today is very good but earlier in time. The one way to be sure was to run outboard oil. It usually complies to somewhat stricter regulations and has always worked excellent in dirt bikes. I have used outboard oil since the late seventies and never ever had a problem related to that. Infact I used to have a Maico 250 -83 that I never changed the spark plug in during the time I had it, some 3-4 years, and I rode a lot!

However, the standars to go for today is JASO-FC and TC-W3! JASO is the japanese manufacturers quality measurements which is based on actual testing regarding lubrication, friction and so on. A JASO-FC oil will be just fine. If you want to be even more certain, look for a TC-W3 compliant oil. It's guaranteed to keep the engine cleaner yet very protective against seizure.

I'd say that any oil meeting both standards will be more than enough and the oil will never be the problem. However. I'm not a friend of too little oil in the mix. Especially not on the open class sized bikes. The piston would probably get away just fine with 1-2% but not the crankpin bearing. And to make things a little more complicated. The open class bikes doesn't burn oil too good. So we need the oil but the pipe will be clogged on the inside. That's why I preffer a TC-W3 compliant "MINERAL" oil at around 3-3.5%. The mineral oil will generally burn better than the syntetic oil. 250's and smaller bikes would probably do better with syntetic oil.

I would guess that riding style means quite a bit too. The enemy is the RPM. That is what requires better oils with more strength and higher temp resistance.

this in my thoughts, no guarantees...

[brokenb23]

Keep it simple. Lots of good oils, users choice. Mixes equal- tighter clearance heavy mixture/20:1  Looser clearances less mixture- 30, 40 50:1

[Dwight Rudder]

Golden Spectro is same as old HiPoint oil but they tell you to mix at 50:1. I found that the old mixture of 40:1 leads to longer engine life.
But the reason for the 50:1 is that Golden Spectro burns extremely dirty and will clog a modern spark arrestor in short order.
I found that Bel-Ray mixed at 50:1 is asking for a failed crank bearing.
I use Maxima Super M at 40:1 and it burns very clean. Maxima Castor 927 is very good but a dirtier oil. BUT it smells like Castor. But it is much cleaner than straight Castor oil.
Helmut Clasen uses and recommends Optimol brand oil, mixed at 80-100:1 I too have used it with decent results. I use it in my Aeroplane engine ( Hirth 2 stroke, 625cc ) but is is a faily low rpm engine.
Remember the higher the RPM the more oil it needs due to oil migration through the engine. 500cc 2 strokes turn low rpm and need less oil as the oil moves slower through the engine. 100cc engine turns much higher RPM and needs more oil.  40:1 seems to be a good comprimise on most good oils.
I would say that optimal ratio's with a oil like Maxima Super M would be:
50-100cc = 32:1
125cc = 36:1
175cc-250cc = 40:1
350cc-500cc = 50:1

I don't recommend Outboard motor oil unless you have too. They are designed for Water Cooled Engines not Air Cooled, and at lower RPMs. Cheaper brands also are very smokey. You should have seen my Suzuki T250 Hustler when I ran Union 76 Outboard oil. It looked like I was spraying for Mosquitos. Similar results with Chevron oils in my friends Kawasaki Triple 500cc H1. I have run Penzoil Semi-Synthetic in my KE100 Kawasaki oil injection system. Looks a lot like Suzuki CCI oil.
By the way if you are premixing Suzuki CCI , which is a very good oil it is designed to be run at 20:1 and burns very clean at this ratio.
We ran this oil exclusively with the Suzuki Team Enduro in the late 70's and early 80's. I had started with the team using HiPoint oil but they made me change. But I found it extremely clean burning with no problems.
Cher'o,
Dwight

Dwight Rudder
7 time ISDT / E medalist
8 time National Enduro Class Champion.

[OUCWBOY]

I don't know if anyone in the OK, KS, AR or TX area would remember this, but there was an oil that was 100% synthetic and came in a clear plastic qt bottle and the oil was pinkish red. I think the name was polyozide or someting like that. Anyway, we ran that out of the two shops I worked at in the late 60's and early 70's and this stuff was the cats meow. I mean we never had a problem with the lubercation or any smoke problems and we ran it 20:1. You could tear down an engine and just take a rag and wipe the head and top of the piston clean with one wipe and the parts still looked NEW. Mike Lewis sold it and Stan's Honda in Duncan OK did too.

Donny Smith

[firstturn]

Oil/gas ratio?
  I get myself in trouble everytime gas, oil and mixture comes up on the Forum.  #1 - Dwight has been racing a long time and I mean a long time [)] and he has seen a lot and he needs no help on his thoughts so Dwight put the calk down and go back to your desk:D.
  Next I have seen some things mentioned that I don't agree with on this Forum so to keep everyone from bailing off with what works or doesn't if it works for you and your happy fine, but I used to be the one (or one of them) that had to recreate the failure of engines for a previous job.  The science is called Failure Analysis.
  Please read the following  and it is just a statement and please I am just putting it out for everyones  approval or disapproval.  I really don't want any dead horses being beat up.

  Oil hopefully lubricates and reduces friction(you NEVER reduce it all).  Bad or lack of lubrication creates Heat.  Heat=More Friction.  The more friction the more heat so on and so on.  The oil that I have tried to use #1 lubricates well at the RPM my engine is operating and #2 if there is a hot spot(or area) developing the characteristic of the oil I use goes to that Hot area.  
 
  That's it, I am not going to discuss clearances because I set up water cooled engines (not just motorcyes only) and air cooled engines differently and the only failures I have ever recorded are people not properly having clean air going in the engine, unless there was a faulty bearing etc.
  Rocket has too many engines under his care to say that his combintion doesn't work.

  See what happens when I take a weekend off[].

Respectfully submitted with all others opinions in mind.

Ron Carbaugh

[Lloyd Boland]

Thanks Ron, but I still don't know, what oil do you use and in your expert opinion, what ratio has worked best for you?

[firstturn]

Lloyd,
  I was hoping you wouldn't ask[].  I use three different mixes.  In my high reving 100/125+cc engines (remember Dwight's comments)  I use Stihl chain saw oil with the little bottles of one bottle for one gallon of gas.  I really like it for air cooled engines, but I don't necessarly recommend it, but I use it. I really have had great years of experience with Yamalube(32:1 or their 50:1).  I actually started using this oil when I was working in Hondaline (accessory part of Honda) and visited with the different people that actually make most of these oils.  The last is I used Honda oil when testing for Honda with no failures, but I don't use it anymore and use the first two choices.
  OK, Rocket(Rod) and I have gone on record with our choices.  Hope this helps.  Lloyd anything else e-mail me directly or ask on the Forum.

Ron Carbaugh

[tomale]

Hmmm, This is very interesting. I may need to make a oil change. I had  been using golden spectro for a long time but I changed because of as Dwight said it did burn dirty. maybe I will try the Maxima or what ever that stuff was. I am interested in a clean burn oil but the thought of having a bearing go because of it... is not a something I am prepared to deal with.
thanks for the info

Thom Green,I own and ride a 76 250 MC5 MX which I bought new.

[firstturn]

Thom,
  If your not having problems I wouldn't change.  I have had sooo many opportunities to test with and for people who wanted to try different oils that's why I am probably out in left field.  Blendzall(green and gold cans) was the best mixture I used for going fast besides going to fuel(which I did before rule changes).

Ron Carbaugh