kx65 mixture???


24 replies to this topic
  • kylerm85

Posted June 02, 2007 - 02:22 AM

#1

how much oil should i be using on a kx65,im currently using 25:1,

  • Chokey

Posted June 02, 2007 - 03:41 AM

#2

25:1 is pefect for a small-bore like a 65 or an 85. Jet correctly for the ratio and weather conditions, and you won't have any problems.

  • Larry63r

Posted June 02, 2007 - 02:55 PM

#3

I run Golden Spectro at 52:1. I run that in all the bikes I have ever had. I have never had any trouble at all.
Run the oil that you like and run the ratio that the oil is made to run at. All oil is different. Some oils are made to run at 20:1, some are made to run at 100:1.
Don't run an oil that is made for 20:1 at 50:1. Also, don't run an oil that is made for 50:1 at 20:1.
We ride MX, mostly at a sand track. My son screams his KX65 all the time. It runs great!

  • Chokey

Posted June 02, 2007 - 05:40 PM

#4

There is no way I would run a 14,000 rpm engine at 52:1, no matter what oil you are using. I wouldn't even run a 250 at that.

52:1 isn't enough oil for any bike that gets ridden hard, especially one that turns as many rpms as a 65 or an 85. And 100:1 is just plain stupid in a 10,000+ rpm race bike.

Looks like it's time for a little pre-mix 101. There are a lot of myths and misconceptions on this subject, maybe this will help some of you to understand a little better.

It's a common misconception that less oil is better, and that too much oil in the mix can foul plugs, and cause spooge. Both are wrong. Spooge and fouled plugs are both caused by rich jetting. And insufficient oil has it's own dangers, that may not always be readily apparent. Running a less than optimal mix ratio has many repercussions,not the least of which are shortened piston and crank bearing life, and power losses that are significant enough to be both measurable on the dyno and felt on the track.

When an engine is jetted too rich, the excess fuel leeches heat from the combustion process, causing the combustion chamber temperatures to be too low to effectively burn the oil, or even completely burn all of the fuel. The result is spooge and deposits. The spooge is nothing more than unburned fuel and oil passing out the exhaust.

If you have a spooge problem or a plug fouling problem, you have a jetting problem. You don't get rid of the spooge or stop the fouling by reducing the oil, you get rid of it by fixing the jetting. Correct jetting will produce an air/fuel ratio of about 14:1, which will produce combustion temperatures in the 2600 degree range, and exhjaust temps in the 1200 degree range. This will provide sufficient heat to consume the premix oil, and to burn off any deposits left on the plug. The spooge and the plug fouling will stop.

You don't choose a mix ratio based on "spooge" or plug fouling, you choose the ratio based on the amount of oil your engine needs to provide sufficient protection and adequate ring seal. The common misconception is that mix ratios are "one-size-fits-all", when in fact nothing could be farther from the truth.The amount of oil that is correct for one rider on his bike may not be enough oil for another rider/bike, or it may be too much oil. The generic reccomendations listed on an oil botle do not take into account what type of bike you are riding, or how hard you ride, and they are biased towards lower emmisions thanks to many years of pressure by environmental groups. The real truth is that the ratio that you should run depends on engine displacement, riding style, and how hard you push the engine.

The best way to determine if you are running enough oil is to check the level of the residual oil in the crankcase. When you are using a sufficient amount of oil in your mix to thoroughly coat and lubricate all of the moving parts, then after the engine is shut down and sits, enough oil will drain down into the crankcase to form a small puddle of residual oil at the bottom. This is your indicator of a correct or incorrect ratio for you and your bike. If the ratio you run leaves about 1/8" to 1/4" of oil sitting in the bottom of your crankcase then you are fine. If you don't have that much residual oil in your crankcase when you pull the top-end off, you aren't running enough oil for your riding style and conditions.

With that said, to have that amount of residual oil in the crankcase at 50:1 (a ratio made popular by magazines and oil bottles), you can't be riding very hard, or your bike is jetted richer than necessary simply to deliver enough oil. I arrived at 26:1 for my bike with my riding style because that is the amount that gives me the proper amount of residual build-up. Small-bore engines require greater oil concentrations than larger engines to achieve the proper amount of residual build-up, because they rev higher and have higher intake velocities. Along the same lines, someone that pushes the engine harder, and keeps the revs higher, also needs to use higher oil concentrations to achieve the proper residual build-up.

To understand why the residual oil is so important, you have to understand what happens to the oil in your fuel when it goes into the engine. While the oil is still suspended in the liquid gasoline, it can not lubricate anything. It has about as much lubricity at that point as straight gasoline. When the gasoline enters the engine, it evaporates, dropping the oil out of suspension. Now that the oil is free, it can lubricate the engine, but it must get to the parts to lubricate them. The way it gets to the bearings and onto the cylinder is by being thrown around by the spinning crankshaft, and the mist of fine droplets being distributed through the engine by the air currents moving through the crankcase. The main bearings are lubed by some of this oil dripping down through tiny "drip passages" in the cases above the bearing pockets.

People believe that the oil just rushes right through a two-stroke along with the fuel, but that just isn't so. It can take 90 minutes or more for the oil migration through a two-stroke to result in a complete oil exchange.

The oil eventually makes it into the combustion chamber, where it is either burned, or passes out the exhaust. If the combustion chamber temps are too low, such as in an engine that is jetted too rich, the oil doesn't burn completely. Instead, some of it hardens into deposits in the combustion chamber, on the piston, and on the power valve assembly. The rest becomes the dreaded "spooge". The key to all of this working in harmony is to jet the bike lean enough to achieve a high enough combustion chamber temperature to burn the oil, but also still be able to supply enough oil to protect the engine. If you use enough oil, you can jet the bike at it's optimum without starving the engine of oil, and have excellent power, with minimal deposits and spooge. At 50:1, you simply can't jet very lean without risking a seized engine due to oil starvation.

With the high oil concentrations that I use, I tend to get far more life from my cranks and rings than most of my friends that run leaner oil ratios. The high oil content also produces better ring sealing, so more of the combustion pressure is retained.

One small point. No one ever broke an engine by using too much oil.

Now we come to the issue of ring seal. Simply put, the rings alone can not effectively seal the cylinder. Even though the rings are pressed against the bore surface by the combustion pressure, the imperfect metal surfaces of both the rings and the bore surface need help to provide a near-perfect seal without damage to the surfaces. The oil helps to complete the seal between the ring face, the piston land, and the bore surface. And up to a point, more oil will provide a better seal.

I have run Dyno tests on this subject, as a school project in Tech School. We used a Dynojet dynamometer, and used a fresh, broken in top-end for each test. We used specially calibrated jets to ensure the fuel flow was identical with each different ratio, and warmed the engine at 3000 rpm for 3 minutes before each run. Our tests were performed in the rpm range of 2500 to 9000 rpm, with the power peak of our test bike (an '86 YZ 250) occuring at 8750 rpm. We tested at 76 degrees F, at 65% relative humidity. We started at 10:1, and went to 100:1. Our results showed that a two-stroke engine makes its best power at 18:1. Any more oil than that, and the engine ran poorly, because we didn't have any jets rich enough to compensate for that much oil in the fuel. The power loss from 18:1 to 32:1 was approximately 2 percent. The loss from 18:1 to 50:1 was nearly 9 percent. On a modern 250, that can be as much as 4 horsepower. The loss from 18:1 to 100:1 was nearly 18 percent. The reason for the difference in output is simple. More oil provides a better seal between the ring and the cylinder wall.

Now, I realize that 18:1 is impractical unless you ride your engine all-out, keeping it pinned at all times. But running reasonable ratios no less than 32:1 will produce more power, and give your engine better protection, thus making it perform better for longer.

And now I'm sure the flames will begin...

  • Larry63r

Posted June 02, 2007 - 06:51 PM

#5

100:1 is for trials riders. They spend most of their time putting around at low RPMs.
I have been running my bikes on Golden spectro at 52:1 since 1970. My father has been doing the same since 1963. We have never seized a motor or had a crank seal go out on any of our bikes.
Do what you want. I am sticking with what works for me. If it ain't broke. Don't fix it!
P.S. That article was written about bean oil.

  • Chokey

Posted June 03, 2007 - 04:08 AM

#6

That article was written about bean oil.

Since I haven't used castor oil in over two decades, I certainly didn't write the article about "bean" oil.

Starting lines all over the country are filled with bikes that run anywhere from 20:1 to 100:1, and with anything from the best synthetic premix to weedeater oil. Most of them survive to play another day, but that doesn't mean that using low oil concentrations is the best or the smartest thing to do. I have many years of testing and measuring used parts to back up my beliefs. But it's OK, run what you want. I won't lose sleep over your bike...:thumbsup:

Just an interesting tid bit since none of us are factory-caliber riders, but Travis Pastrana ran 28:1 in his bike the last year that he raced a two-stroke.

  • spin05

Posted June 03, 2007 - 11:07 PM

#7

stock is 32:1 i run my boys kx65 at 36:1 or sometimes somewere in between.I run synthetic maxxuim.It still smokes quite a bit

  • Larry63r

Posted June 04, 2007 - 12:59 AM

#8

My father was a factory-caliber rider. He has won the 125 pro class at Hangtown.

This is from the Golden Spectro web site.
Our Golden Spectro 2-cycle pre-mix product is designed to be used at higher ratios than conventional 2-cycle lubricants. Because of its synthetic components, additive content and viscosity, it works best at ratios from 40:1 to 64:1. We recommend starting at 40:1 in older machines and checking your exhaust pipe for excessive drool. If you have a large volume of drool, go to a higher mix ratio until the drool is minimal. You will have all the protection you need and yet have very crisp throttle response and never foul a plug following these recommendations.

  • JBFL

Posted June 04, 2007 - 03:48 AM

#9

I've been running Maxima K2 @ 40:1 for over a year now and can hardly see wear in the cylinder. When warmed up there's just a slight amount of smoke out the pipe.

  • ebeck

Posted June 04, 2007 - 02:56 PM

#10

The factory recomends 32:1 for the KX65. Unless you need the extra .75 hp I'd stick with what the factory recomends and then jet just shy of rich.

Some people go nuts with trying to squeeze extra power by runing lean. yeah, oil or lack of it is not how ti get HP or snap. Just add a big bore kit or compresion if HP is what you want is my opinion on that.

Do what the factory recomends. But that's me, shrug.

  • EastBoundAndDown

Posted June 04, 2007 - 04:01 PM

#11

Amsoil Interceptor @ 50:1... No problems to speak of.

  • Chokey

Posted June 04, 2007 - 05:42 PM

#12

My father was a factory-caliber rider. He has won the 125 pro class at Hangtown.

This is from the Golden Spectro web site.
Our Golden Spectro 2-cycle pre-mix product is designed to be used at higher ratios than conventional 2-cycle lubricants. Because of its synthetic components, additive content and viscosity, it works best at ratios from 40:1 to 64:1. We recommend starting at 40:1 in older machines and checking your exhaust pipe for excessive drool. If you have a large volume of drool, go to a higher mix ratio until the drool is minimal. You will have all the protection you need and yet have very crisp throttle response and never foul a plug following these recommendations.

Amazing...even a major oil manufacturer is spreading the myth that you reduce the oil amount to reduce spooge...simply amazing. I guess that's what happens when the marketing guys write the label instead of the engineers...

  • EastBoundAndDown

Posted June 05, 2007 - 03:14 PM

#13

Listen here, chokey. I was running amsoil @ 40:1 and had X spooge. now that I started running 50:1, I have 1/2 X spooge. Am I crazy? Jetting stayed the same, temp difference was minimal.

I have heard that the spooge coming out od the muffler is actually gasoline. True?

  • kx_rider53

Posted June 05, 2007 - 04:48 PM

#14

The "spooge" is actually unburt oil coming out the exhaust. To reduce oil in the fuel mixture is stupid, as it replenishes the oil supply that lubes the bottom end and promotes ring seal. To reduce the spooge and plug fouling requires leaner jetting, as chokey said. The leaner jetting will raise crown temperatures, burning off any excess oil, while keeping hp up with improved ring seal, and the bottom end will be happy. Chokey is right in everything he said. I would never run less (oil) than 32:1 in a 65, if not 26:1 or so.

  • Chokey

Posted June 05, 2007 - 05:09 PM

#15

Listen here, chokey. I was running amsoil @ 40:1 and had X spooge. now that I started running 50:1, I have 1/2 X spooge. Am I crazy? Jetting stayed the same, temp difference was minimal.

I have heard that the spooge coming out od the muffler is actually gasoline. True?


Of course you had less spooge when you mixed less oil, because there was less oil to pass through the engine unburned. But that's not the correct way to fix spooge. Correct jetting will produce combustion temperatures high enough to consume the oil, regardless of how much oil you mix in your fuel.:thumbsup:

You're looking at it through the wrong end of the telescope. The spooge isn't telling you that there is too much oil in your fuel, it is telling you that your bike isn't jetted quite right. If you correct the jetting problem, not only will your spooge stop, your bike will also run better. It will be crisper and more responsive. Kinda neat how that works out, huh...

Yes, the spooge is unburned fuel and oil that is passing through the engine. Rich jetting drops combustion temperatures too low to allow for complete combustion.

I can go mix up a batch of 20:1 fuel right now, dump it in the bike, and with a quarter-hour of jet testing, I will have a spooge-free bike that runs crisp and clean. So don't tell me that you fix spooge by running less oil, because I know better.

This is why I usually stay out of spooge and mix-ratio threads. People have been so brainwashed by that pervasive myth that too much oil causes spooge that they just don't want to be told that they are wrong.

You can walk through the pits at nearly any track and find someone with a spooge-covered bike that's running 40, 50, and even 60:1, often because they too were told that reducing the oil in their mix would clear up their spooge problem. Should they also reduce the amount of oil in order to stop their bikes from spooging? Should the guy running 60:1 go to 100:1 so he won't have spooge anymore?

I try to educate people on the fallacy of "excess oil causes spooge". There's no rule that says anyone has to believe what I say or do it. You are free to do things the way you want, or the way Uncle Billybob tells you, or even the way your ignorant dealer tells you. I still won't lose any sleep over it...:)

  • spin05

Posted June 05, 2007 - 11:08 PM

#16

So your saying to lean it out???If so were would a guy start? Drop down on the main perhaps???

  • Yamajeb

Posted June 06, 2007 - 01:41 AM

#17

Jet by WOT chop, never spooge . . . that stated, spooge = unburned fuel & oil and typically corrects itself with proper jetting (there CAN be other reasons to have spooge but those are probably not typical. Porting Gone Wild is one reason

  • Chokey

Posted June 06, 2007 - 05:43 PM

#18

So your saying to lean it out???If so were would a guy start? Drop down on the main perhaps???


Jetting 101:

A correctly jetted carb makes a tremendous difference in the torque, midrange pull, top-end pull, and over-rev of your engine. If you have never jetted your bike correctly, you will almost certainly gain some performance at some point in the bike's powerband.

A cleanly jetted pilot circuit can be the difference between having to clutch the bike out of a turn or not. Hard starting when hot or cold, poor response when opening the throttle, reluctance to idle, all of these are symptoms of an improperly sized pilot jet or incorrectly adjusted air screw.

The needle can make all the difference in the world for the power of the machine in most situations, as it controls the throttle range that most riders spend most of their time using.

A correctly sized main jet could mean the difference between being able to rev out high enough to not have to shift one more time at the end of the straight, or the power falling flat on top and requiring you to make that extra shift.

Are you fouling plugs? Many people will tell you all sorts of band-aid fixes, from running less oil, to running a hotter plug. Both are incorrect fixes for plug fouling. It's all in the jetting. An engine that is jetted too rich will have combustion temperatures that are too low to burn the fuel and oil effectively, leading to deposits and wet fouling of the plugs.

Do you have spooge? There are the rare instances where a mechanical issue, such as a leaking wet-side crank seal, can cause spooge. But, by and large, this isn’t the case. In most instances, spooge is caused by rich jetting. It has nothing to do with how much oil you mix in the gas, or how hard you ride. An engine that is jetted too rich will have combustion temperatures that are too low to burn the fuel and oil effectively, resulting in deposits, plug fouling, and spooge. Spooge is nothing more than unburned fuel and oil entering the exhaust.

The only way to know what jetting changes you will need is by trial-and-error. No one can give you jetting specs, because every bike is different, every rider has a different style, and jetting is totally weather dependent. Unless the person telling you what jets to use is riding an identical bike, on the exact same track, at the same time, his recommendations are meaningless. Someone with a good understanding of jetting can get you in the ball park, but you need to do the testing to determine the correct jetting yourself if you want it right.

Jetting is fairly simple, and is a useful skill to learn if you ride a two-stroke and want it to perform at it's best.

It's very important that you start with the pilot circuit, because the pilot circuit affects the entire throttle range. When you are at full throttle, the main jet is the primary fuel metering device, but the pilot is still delivering fuel as well, adding to the total amount of fuel that your engine is receiving.

Before you start to re-jet your bike, you need a clean air filter, a fresh plug (actually you need several plugs to do plug-chop tests for the main jet), and fresh fuel.

One important detail: Make sure the engine is in good mechanical condition. If your engine has a worn top-end, fix it first. Trying to jet a worn out engine is a waste of time. The same goes for reeds that don't seal properly, and a silencer that needs re-packing. Worn reeds will mimic rich jetting, and worn rings will mimic lean jetting.

Before you start the jet testing, Install a fresh plug. Set the float level to the proper specs, an incorrect float height will affect your jetting all across the throttle range.

All jet testing must be done with the engine at full operating temperature.

As already stated, start with the pilot circuit. Turn the air screw all the way in, then turn it out 1.5 turns to start. Start the engine, and turn the idle screw in until you get a slightly fast idle, or hold the throttle just barely cracked, to keep the engine idling. Turn the air screw slowly in, and then out, until you find the point where the idle is fastest. Stop there. Do not open the screw any farther, or your throttle response will be flat and mushy, and the bike may even bog. This is only the starting point, we will still have to tune the air screw for the best response.

Now is the time to determine if you have the correct pilot installed in your carb. The air screw position determines this for you, making it very simple. If your air screw is less than 1 turn from closed, you need a larger pilot jet. If it is more than 2.5 turns from closed, you need a smaller pilot jet. If your engine doesn’t respond to air screw changes, then you either have a dirty carb, or the pilot jet is way too rich. When the pilot jet is way too rich, you are forced to use the idle screw to open the slide so far in order to keep the engine running that the pilot circuit is partially bypassed, and the engine is actually starting to draw fuel through the needle jet.

Once you have determined (and installed it if it's necessary to change it) the correct pilot jet size, and tuned the air screw for the fastest idle, it's time to tune the air screw for the best throttle response. Again, make sure the bike is at full operating temperature. Set the idle back down (the bike should still idle, despite what you read in the Moto Tabloids), and ride the bike, using closed-to-1/4 throttle transitions. Turn the air screw slightly in either direction until you find the point that gives you the best response when cracking the throttle open. Most bikes are sensitive to changes as small as 1/8 of a turn.

The air screw is not a set-it-and-leave-it adjustment. You have to constantly re-adjust the air screw to compensate for changing outdoor temps and humidity. An air screw setting that is perfect in the cool morning air will likely be too rich in the heat of the mid-day.

Now, it's time to work on the needle. Mark the throttle grip at 1/4 and 3/4 openings. Ride the bike between these two marks. If the bike bogs for a second before responding to throttle, lower the clip (raising the needle) a notch at a time until the engine picks up smoothly. If the bike sputters or sounds rough when giving it throttle, raise the clip (lowering the needle) until it runs cleanly. There isn't really any way to test the needle other than by feel, but it's usually quite obvious when it's right or wrong. A too-rich needle can often be felt simply when revving the bike on the stand. The bike will sound rough and raspy when blipping the throttle on the stand. A correctly jetted bike should rev cleanly and crisply.

Last is the main jet. The main jet affects from 1/2 to full throttle. The easiest way to test it is to do a throttle-chop test. With the bike fully warmed up, find a long straight, and install a fresh plug. Start the engine, and do a full-throttle run down the straight, through all gears. As soon as the bike tops out, pull the clutch in, and kill the engine, coasting to a stop. Remove the plug, and look deep down inside the threads, at the base of the insulator. If it is white or gray, the main is too lean. If it is dark brown or black, the main is too rich. The correct color is a medium-dark mocha brown or tan.

Please note that, when reading plugs, the tip of the insulator, threads, etc. are meaningless for jetting purposes. They can tell you a lot of things, but jetting isn’t one of them. Only the mixture ring at the very base of the insulator, inside the threads, can tell you anything about the jetting.

These links should help you to understand reading plugs:

http://www.tsrsoftwa...s/sparkplug.gif

http://www.tsrsoftwa...files/sparkplug b-w .gif

The slide is also a tuning variable for jetting, affecting the throttle range from 1/8 throttle to approximately 1/3 throttle. If you can’t clean up the small-throttle jetting on your bike no matter how lean you go with the pilot or the needle, the slide is the next step. But few bikes need leaner slides.

Keep in mind, even though this article is intended primarily for two-strokes, four-strokes also need proper jetting to perform right, although they are not quite as fussy as their oil-burning cousins. The only real difference in the two is with the pilot circuit.

Two-strokes have an air screw that you screw in to make the jetting richer, and screw out to make the jetting leaner. Four-strokes, on the other hand, have a fuel adjustment screw that you screw in to make the jetting leaner, and out to make it richer. Their purpose is the same, they just do it in different ways.

Four-stroke carbs also use an accelerator pump. By nature, four-stroke engines have a much weaker vacuum signal to the carb at small throttle openings, so they tend to hesitate when whacking the throttle open, because it takes a small amount of time for the weaker vacuum signal to begin drawing fuel up through the jets. To compensate for this, the accelerator pump squirts a small stream of fuel into the carb throat. The accelerator pump must be correctly adjusted for flow volume and timed for flow duration. Too much fuel squirt, and the bike can flood, especially on a tight track where frequent off-on throttle transitions are necessary. Too little, and the bike bogs coming out of turns and when landing from jumps. Every four-stroke model is different, so refer to your manual for correct adjustment of the accelerator pump.


  • kx_rider53

Posted June 06, 2007 - 05:53 PM

#19

:thumbsup:

  • naturaledge

Posted June 07, 2007 - 08:55 AM

#20

Amazing...even a major oil manufacturer is spreading the myth that you reduce the oil amount to reduce spooge...simply amazing. I guess that's what happens when the marketing guys write the label instead of the engineers...


Listen to Chokey:prof: My son runs his at 32:1 (Amsoil interceptor). He still gets some spooge but that has nothing to do with the mixture, it has everything to do with his riding style and jetting. He just doesn't run up on the pipe enough yet.





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