premix?

chainsaw · Post by **chainsaw** » Thu Jul 16, 2009 10:41 pm

I am about to try and get my bike running again. My pump is still intact and working. I did take off the oil tank while going thru the machine. Just for safety, I am wanting to run my first few short rides with some premix as well as make sure the pump is working and no bubbles in the lines.

what mixture should I use? 20:1? more?

tz375 · Post by **tz375** » Thu Jul 16, 2009 11:27 pm

That's a good question, because it raises the issue of why do it and what are we trying to achieve.

There are probably as many answers as people on this forum, but my opinion is that it's not crucial. As a belt and braces approach, I would add oil to the first small fill in almost any ratio between 20 and 50:1. Half a gallon is enough.

I would fill the lines with a different color oil to the oil in the tank and fire it up. Within minutes all the lines should change color. If they don't, crank open the pump and keep the motor running at fast idle for a few minutes.

Once all the lines are looking good, fill the rest of the tank with straight gas and go riding. there is no point in filling a whole tank with premix and running the bike without checking waht is going on. That's not effective. The idea, is to keep it safe for those first few minutes while you check that the pump is OK.

Post by **Suzsmokeyallan** » Fri Jul 17, 2009 6:52 am

Ratios are the reverse of what most people think, therefore an engine with the carb jetted for a 20:1 mixture of premix will run RICHER on a 32:1 and even more so with 50:1.
So try to stay at least in the 25:1 ratio which is very close to the jetting on a stock Buffalo.
Richard is spot on, just add enough of a small amount of premix to get the engine running so you can establish the CCI system is working on all lines.
You do not need to ride the bike either, just start it and run it up to a little above idle and hold the pump lever setting at wide open.
Since you have oil already in the lines using a different coloured oil in the tank will tell you if the oil is moving along the lines since you will be able to see whats happening.
Once youve established the CCI system is functioning then you'll only need to set the pump lever to the 'new' iron butt Allen setting for the modern oils of today.

chainsaw · Post by **chainsaw** » Fri Jul 17, 2009 8:11 am

OH lordy, not to start an "which is the best oil" thread...........what is the best COLOR of oil to use??? (joke)

thanks for your suggestions guys

Post by **Suzsmokeyallan** » Fri Jul 17, 2009 10:01 am

Since your bike is orange/red use the reddish Bardahl cause it matches,,LOL,,besides H2Rick likes that brand and so do i.
There you go now you will have appeased the Calgary 'oil forum' god.

TLRam1 · Post by **TLRam1** » Fri Jul 17, 2009 2:09 pm

Suzsmokeyallan wrote:Ratios are the reverse of what most people think, therefore an engine with the carb jetted for a 20:1 mixture of premix will run RICHER on a 32:1 and even more so with 50:1.
So try to stay at least in the 25:1 ratio which is very close to the jetting on a stock Buffalo.
Richard is spot on, just add enough of a small amount of premix to get the engine running so you can establish the CCI system is working on all lines.
You do not need to ride the bike either, just start it and run it up to a little above idle and hold the pump lever setting at wide open.
Since you have oil already in the lines using a different coloured oil in the tank will tell you if the oil is moving along the lines since you will be able to see whats happening.
Once youve established the CCI system is functioning then you'll only need to set the pump lever to the 'new' iron butt Allen setting for the modern oils of today.

Allan,

You stated a while back the Buffalo oil pump could be turned down where at idle the pump is in it's relaxed position, is this correct?

I turned my down some but not to that extent, I am double checking with anyone so problems do not pop up.

So does this mean that with Lane's bike set at factory specs and his jetting is larger for performance done to his motor he is running at a greater ratio gas to oil mixture (more gas less oil than a stock) or the difference in jetting is so small it's immaterial?

Post by **Suzsmokeyallan** » Fri Jul 17, 2009 3:44 pm

Terry i came to this conclusion by how the stock engine with stock jetting was burning the fuel/oil mixture. In the end i set the pump so when the throttle is at idle the pump lever is at the full off rest stop position.
Iron butt Allen also uses this position and we had a discussion a while back by coincidence about how the oil mixture ratio is perfect at this setting on a stock bike when using MODERN two stroke oils.
My stock 76 Buffalo is working perfectly at this setting with stock jetting and the plugs are a good light tan colour with the rear of the baffles looking dry, but not that dry if you know what i mean.
You might feel a bit uncomfortable going to such a new position on your bikes pump, but still feel comfortable moving it back a bit.
Why not try a slightly reduced output setting and then take a plug reading for comparison.
The reality of a set mixture ratio is that you tune the carbs jetting to what you are using, even if the engines got chambers and performance work.
With modern oils and their characteristics a 20:1 ratio is now obsolete, you will find 25:1 and 32:1 to be the most common for land based two stroke engines now.

TLRam1 · Post by **TLRam1** » Fri Jul 17, 2009 5:14 pm

Yes, all of this makes sense and on my KX250 it calls for 32-1 and I run 40-1 as that is time tested by enough people and works well. On the Buffalo I didn't know and for sure do not want to have an issue so I wanted to check again before I put many miles on it like this.

It's not back to it's off position but close, I guess the pump still pumps in it's "off relaxed" position and never stops as long as the motor is running. I guess any 2-stroke oil purchased these days would be considered a modern 2-stroke oil.

Barry S. · Post by **Barry S.** » Fri Jul 17, 2009 7:28 pm

For a Buffalo to use oil at a 25/1 ratio sounds way excessive to me, that would be a quart of oil to every 25 quarts of gas, or a quart per 6 gallons or so, a quart every tank and a half. I think it should be a quart every 500 or 600 miles, 1000 miles per oil tank full.

tz375 · Post by **tz375** » Fri Jul 17, 2009 10:26 pm

Obviously changing the pump settings makes no difference to the air:fuel ratios but it will change the average amount of oil used: fuel used.

There's an old myth that goes something like this" if you add more oil to a premix bike, there's less fuel per unit of liquid consumed so the thing will run lean". Or words to that effect. In an absolute mathematical sense that's true but small changes are basically immaterial.

As Allan said, modern oils are way better than anything around back in the day, and Suzuki were a little bit conservative even then. So with a good oil, it should be possible to reduce the amount of oil by backing off the pump adjustment.

I come form the old school where more oil was better, which has been proven many times so I don't recommend it, but for street riding it's probably OK to back the pump off slightly.

Post by **Suzsmokeyallan** » Sat Jul 18, 2009 10:02 am

Richard please clarify that oil statement in the last post of yours, did you make a typo??? "more oil was better which has been proven many times so i dont recommend it" is that correct.
I know that you know this following info but we are generalising here for the topic so i will add this.
When Suzuki had the pre premix era of bikes with their little white bottles held in the side covers, it worked out to be a ratio of around a 1/2 pint to a gallon of gasolene or around 20 to 1.
I'd say they stuck very close to this for a long time, and the name of the bikes smoking a lot got them labelled around here as a Suzsmokey.
The old two stroke oil formulas were very poor quality and no where near as clean burning as those of today, but using roughly what equates very closely to a 20 to 1 setting in a CCI system is not necessary now.
If you reduce the ratio of oil to gasolene you increase the ability of the gasolenes particles to flow more freely through the orifices in the carb.
You can see this by setting the carb jetting on a single cylinder engine for a 20 to 1 ratio then switching it out to a 32 to 1. Upon starting it up and riding it you will need to drop the needle at least one notch, reduce the pilot size or turn out the airscrew and possibly drop the main jet by 0.5.
This tells you immediately that the 32 to 1 mixture is somehow richer overall than the 20 to 1, or in this case richer to the fact the engine is getting a percentage more fuel than before.
The reason you get more smoke with more oil is because the engine cant efficiently burn all the oil off properly so its being dumped into the hot exhaust pipe where its building up as smoldering carbon.
Dont forget the pumps delivery is not fixed, its got an output delivery curve, so just as your fuel mileage varies by riding style and terrain your oil consumption will also vary.

tz375 · Post by **tz375** » Sat Jul 18, 2009 10:37 pm

Allan,

poor sentence construction on my part, leading to ambiguity.

What i was saying is that I believe that more oil is better and therefore I do not recommend reducing the oil supply as suggested in the post, but I reluctantly agree that it may be OK on a street bike not ridden very hard.

Hope that's easier to understand the intent.

Post by **Suzsmokeyallan** » Sun Jul 19, 2009 7:10 am

Richard i see your merit but remember the oil pumps output delivery is not fixed, so however you look at it more oil in this case isnt better.
Also,, consider the small two stroke engines of the motocross bikes, the 100 and 125 cc sized engines etc are regularly at 10.000rpms in race conditions and they use a 32 to 1 ratio with no seizing.
However yes,,, the REAL race engines get pulled fully down after a race for a full inspection and thats a whole different story.
Having looked at the Suzuki model history book recently it states they were still using 20 to 1 for the RM dirt bikes of the late 70s. So if form follows function it would not be difficult to figure out what they using in the CCI bikes as a pump ratio at that time with the old style oils.

tz375 · Post by **tz375** » Sun Jul 19, 2009 10:08 am

Allan,

I follow the reasoning and have no arguement with anyone who wants to try something different and some riders have has success reducing the amount of oil in their CCI machine by changing the adjustment.

The point about using more oil is that in very test so far, motors have run cleaner and made slightly more power on a higher oil:fuel ratio up to about 20:1 or so depending on the oil and the motor and the test conditions etc.

Those tests were typically done with high grade oil, so the results are still valid, but they were all wide open throttle dyno runs

Now the question that's relevant today is whether an engine run at lower loads would benefit from more or less oil.

Much as we would like to, we cannot draw any conclusions form reading manufacturers specs for oil:fuel ratios unless we know a whole lot more about the tests and hwy they used more or less oil. Air vs water cooled, better combustion temperature control through better electronics etc etc.

A modern TZ or RS125 runs basically the same sort of pre-mix ratios as racers from years gone by (25-32:1)

That said, one could hypothesize that a motor running at lower laod levels would not get as hot and the risk of lubrication breakdown is reduced. In addition, the running temperatures will be lower and it is possible that the "extra" oil might not be burned off as cleanly as on the test motors at full throttle.

Of course the Suzuki CCI pump is variable with throttle opening so it varies with load, and with RPMs and it is entirely possible that a street motor could get away with a lower output undr most conditions.

One thing to remember is that it reaches maximum stroke at a lever angle of just 37 degrees (half way open). That means that backing off teh adjustment will slow the rate of opening so that it reaches full output at say 5/8 thottle, so you are still protected at WOT.

Backing off the adjustment slightly will reduce oil consumption at all throttle openings up to around half throttle which is where most of us ride for 95% of the time.

So go ahead and back it off slightly.

doug rooney · Post by **doug rooney** » Sun Jul 26, 2009 4:32 pm

Anybody know what a T20 premix should be? I already trashed one piston due to oil starvation and don't want to do it again. Will prime the pipes with a different colored oil as you guys say just to make sure it's moving in the lines. Going to use 1 gallon of premix fuel just in case.
Thanks, Doug

Quite sure I have a pump that works right now until I can find a NEW one.