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Is your two-stroke running rich? Read here.




280 replies to this topic
  • Motocross26

    TT Gold Member

1,430 posts
Location: New Hampshire

Posted September 03, 2006 - 03:17 PM


Is there drool "spooge" running down your silencer at the end of a ride? Does your bike smoke at operating temperature? Do you foul plugs on a regular basis? Is your throttle-response poor and boggy?

If you answered "yes" to any, or all of these, your problem likely lies in your carburetor jetting.

The first step to jetting is setting the correct float height.

Article by: Faded
"Here are a few words and some pictures I put together to help eliminate the confusion in setting your float level. Obtaining the correct float level is of the utmost importance as it can affect all jetting circuits. THE FLOAT LEVEL IS THE FIRST STEP TO PROPERLY DIALING IN YOUR JETTING. It should be checked and/or set before you even think about swapping brass. By altering the volume of fuel in the float bowl you can vary your fuel pressure and affect your jetting. More fuel in the float bowl will create more fuel pressure and result in rich(er) running conditions and vice versa.

You’ll need to first start off by removing your carb. Be sure to clean the surrounding area to the best of your ability to avoid dirt and debris falling into your carb, or worse, your engine. After you’ve removed your carb I would suggest a thorough cleaning using carb cleaner (or equivalent) and compressed air to ensure that all jets and passageways are spotless. Avoid using wire or other tools to clean orifices of jets; it’s all too easy to alter their original designed dimensions.

After your carb is clean you can now set your float level. The picture below will allow you to become familiar with the parts that are responsible for maintaining the correct float level in your carb. There are four basic parts, the floats themselves (part of the float assembly), the float assembly tang, the fuel inlet needle valve, and the fuel inlet valve seat.
Posted Image

(Float assembly pivot pin not shown.)


It is always a good idea to remove the float assembly pivot pin (already shown removed) and extract the float assembly and the fuel inlet needle. The fuel inlet needle is a wearable part and over time can deteriorate. A worn fuel inlet needle can contribute to an irregular float level. Most fuel inlet needles consist of an internal spring loaded bumper (which contacts the float assembly tang) and a plastic or Viton (rubber) tip. Inspect the fuel inlet needle tip for wear and/or damage. To give you an idea, Eric Gorr recommends replacing the fuel inlet needle/seat assembly every two years. I’ve found that the average cost it around $15 for both parts.
Posted Image

(Fuel inlet needle shown with Viton (rubber) tip. The Viton is used to isolate the fuel inlet needle from vibration and to create a better seal against the fuel inlet valve seat.)

Now that you’ve made sure you aren’t going to have any issues from worn parts you can reinstall your needle, float assembly and float assembly pivot pin and continue on to set your float level. The float level measurement is taken from the top of the floats (when the carb is positioned upside down) to the gasket surface of the float bowl as illustrated in the next picture. You can use an open-end wrench (sized per your spec), a small metric ruler, or a float level gauge. The tolerance for your float level is usually around +/- 0.50mm.
Posted Image



When setting the float level be aware that the spring loaded bumper on the fuel inlet needle valve may have a tendency to compress under the weight of the float assembly which will skew your measurement. Before you obtain your measurement you’ll need to make sure that the float assembly tang just barely makes contact with the spring-loaded bumper. Sometimes it is easier to hold the carb body at a 45-degree angle to avoid compressing the spring in the fuel inlet needle.
Posted Image



If you find that your measurement does not match your float level spec then you can carefully bend the float assembly tang to achieve your desired measurement. Be sure to recheck your work, and if you feel confident that your float level is spot on then you can reinstall your carb and get back to riding."

END OF ARTICLE


Now that you know that you have the correct float height, you can start swapping out brass.

Words of Assurance: Jetting isn't hard and comes with practice. You're not going to mess your bike up unless you make huge changes. You WILL be able to tell if your bike is running lean enough to be in danger of seizing. So, don't worry.


Article by Spanky:

"Throttle Ranges:
Pilot Jet/air screw:0-1/4.
Needle Jet:1/4-3/4
Main Jet: 3/4-Full open

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 power band. A cleanly jetted pilot circuit can be the difference between having to clutch the bike out of a turn or not. 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.

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.

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. The reason is simple. 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 rejet 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.

Before you start the jet testing, Install a fresh plug. Warm the bike completely, and shut it off.

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 airscrew 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.

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.

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.

Once you have a little bit of experience with jetting changes, and you start to learn the difference in feel between "rich" and "lean", you'll begin to learn, just from the sound of the exhaust and the feel of the power, not only if the bike is running rich or lean, but even which one of the carb circuits is the culprit.

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."

END OF ARTICLE

NOTE:
REMOVING (leaning) oil from the GAS/OIL mixture makes your AIR/FUEL mixture RICHER, effectively making your engine run RICHER (more smoking/spooge) . If you remove oil from your premix mixture, you have more gas in a specific amount of fuel. Making the mixture that really matters, the air/fuel mixture, richer. Do not fix jetting issues by changing your premix ratio.

If you guys like this little article, it would be nice if we could get this stickied in all of the two-stroke forums, to avoid the same questions being asked over and over again.

I hope this helps.
:thumbsup:

  • MikeD94

    TT Member

82 posts
Location: Missouri

Posted September 06, 2006 - 01:37 PM


Mod edit and an addition as suggested by Alex...KXrider 53....jetting is dependent on other factors besides weather and oil/gas. You must have a bike in good condition (air filter clean, silencer re-packed, fresh top end, consistant gas, crank seals good, etc) Other wise, jetting a bike that is worn is like going in circles. This needed to be at or near the top of this jetting guide. Thanks RC


Nice job putting together this write up! But I think there's a minor error at one of the paragraph shown below.

"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."

I'm sure you meant that you need a smaller pilot jet if air screw is less than 1 turn and a larger pilot jet if air screw is more than 2 turns. Keep in mind that it's opposite of the 4 stroke carbs regarding air/fuel screw.

  • velosapiens

    Get Help Now

5,280 posts
Location: Idaho

Posted September 06, 2006 - 01:46 PM


I'm sure you meant that you need a smaller pilot jet if air screw is less than 1 turn and a larger pilot jet if air screw is more than 2 turns. Keep in mind that it's opposite of the 4 stroke carbs regarding air/fuel screw.


wrong. the original article is correct. turning the air screw out lets in more air, leaning out the idle mixture. if you need it so lean that you have to go to 2.5 turns out for normal conditions, then you should go to a leaner (smaller) pilot jet.

  • NYMXer
4,506 posts
Location: New York

Posted September 06, 2006 - 01:50 PM


This is a very good write up and has many worthy points. Spooge is due in 'part' to poor jetting but it is also due to the wrong mixture and low exhaust temps. If you changed nothing other than rode harder which would cause raised exhaust temps, most of the complaints would go away. In other words, ride that bike harder and the spooge will most likely disappear. If it still doesn't then you need to look closer at your jetting and fuel mixture. :thumbsup:

  • Vetmxrider

    TT Bronze Member

455 posts
Location: California

Posted September 06, 2006 - 06:15 PM


Great job of putting all this information together. :thumbsup:
Special thanks for walking everyone through the thought process that trying to use less mixing oil in the pre-mix to reduce spooge will only make the problem worse. That point alone has caused many bench racing wars until both sides see the logic. Thanks again!

  • MikeD94

    TT Member

82 posts
Location: Missouri

Posted September 07, 2006 - 05:31 AM


wrong. the original article is correct. turning the air screw out lets in more air, leaning out the idle mixture. if you need it so lean that you have to go to 2.5 turns out for normal conditions, then you should go to a leaner (smaller) pilot jet.


Oh, my bad! I stand corrected big time! Sorry.

  • Murray Dorward

    TT Bronze Member

165 posts
Location: South Africa

Posted September 08, 2006 - 10:30 PM


I have yz250 (N) 2001 model and have the following problem.
From a cold start with the choke out, I kick the shit out of it
and the bike will not fire up. When the engine is warm I have no problems what so ever as the engine runs sweet and no misfires.
I replaced the needle in the seet in the carb and have set the float level in the carb as per specifications in the owners manual. I have also put in a new NGK9EG spark plug, cleaned the air filter and checked the rubber boots on both air filter side and inlet side of carb for holes sucking in air, but still bike will not start. But if I lie the bike down on the ground on its side and let some petrol spill through the overflow pipes and pick it up again and use the kick start it starts 1st or 2nd kick. Why???????????????
If any one has any ideas why the bike will not start when cold please give some advice, apart from sell it and buy a four stroke as I have allready ordered a WR450 - 2007

Muz

  • Motocross26

    TT Gold Member

1,430 posts
Location: New Hampshire

Posted September 09, 2006 - 05:31 AM


Clean the carb first, especially the pilot jet and idle circuits.

If that doesn't help, trying upping the pilot jet one size.

  • CrackedCase71

    TT Newbie

4 posts
Location: Montana

Posted September 21, 2006 - 04:39 AM


I was having the same problem as Murray with my 490, so I dropped it down two sizes on main jet played with the air/fuel mixture till it was right. Now it starts 2nd or 3rd kick.

  • MikeD94

    TT Member

82 posts
Location: Missouri

Posted September 21, 2006 - 08:39 AM


I was having the same problem as Murray with my 490, so I dropped it down two sizes on main jet played with the air/fuel mixture till it was right. Now it starts 2nd or 3rd kick.


Did you meant to say you dropped pilot jet down two sizes? If not, I don't see how changing main jet affects starting. If so then please explain.

  • Coop39

    TT Bronze Member

211 posts
Location: Utah
Garage View Garage

Posted September 21, 2006 - 07:13 PM


An air screw setting that is perfect in the cool morning air will likely be too lean in the heat of the mid-day.


I would say if it is set for cool morning air ( most likely you would turn in the air screw for cooler air) So then in the afternoon with warmer air, you would lean out the mixture (turn air screw out) for the hotter temps. :thumbsup:

  • Motocross26

    TT Gold Member

1,430 posts
Location: New Hampshire

Posted September 22, 2006 - 08:45 PM


I would say if it is set for cool morning air ( most likely you would turn in the air screw for cooler air) So then in the afternoon with warmer air, you would lean out the mixture (turn air screw out) for the hotter temps. :thumbsup:


You're right, I'll fix that.

  • dezryder

    TT Bronze Member

117 posts
Location: Washington
Garage View Garage

Posted October 08, 2006 - 03:31 PM


Your gonna love what ya see.

Check this out:

http://adrenalintrip...pic/178/172870?
siteid=10

The guy (or should I say :thumbsdn: m/c guru) took time to remove the links to the pics and change some of the wording to make it his. :thumbsdn: And then takes in a bunch of kudos for such a great post! Some people... :devil:

  • Tom7036

    TT Newbie

9 posts
Location: Georgia

Posted October 13, 2006 - 05:16 AM


thats a good job on putting that artical toghether but after 30 years of riding and wrenching to thing i see the most is operator error.....basiclly not ridding a 2 stroke correctlly.....most people have a tendency to ride in to tall of gear and not rev it out enough....so if your geting a little spoge at the end of the pipe......try riding harder first...:devil:

  • Motocross26

    TT Gold Member

1,430 posts
Location: New Hampshire

Posted October 14, 2006 - 01:04 PM


Your gonna love what ya see.

Check this out:

http://adrenalintrip...pic/178/172870?
siteid=10

The guy (or should I say :thumbsdn: m/c guru) took time to remove the links to the pics and change some of the wording to make it his. :thumbsdn: And then takes in a bunch of kudos for such a great post! Some people... :devil:


Everything that I did not quote was written by me, I am the original author.

I'm not too worried about the guy stealing my work. Most of the stuff in my article was written by other people anyway, I just put it all together and added some other useful information.

Thanks for bringing this to my attention. I'm flattered to hear that my article was good enough to be stolen. :excuseme:

  • Dr._400

    TT Bronze Member

400 posts
Location: Arizona

Posted November 15, 2006 - 09:03 AM


Great thread it came in very handy last night after I totally had the float hieght wrong.

I had no idea the tange should barely be touching the plunger. :p

Thanks again..........:cheers:

  • timmckey

    TT Newbie

21 posts
Location: California

Posted November 19, 2006 - 08:14 AM


Is there drool "spooge" running down your silencer at the end of a ride? Does your bike smoke at operating temperature? Do you foul plugs on a regular basis? Is your throttle-response poor and boggy?

If you answered "yes" to any, or all of these, your problem likely lies in your carburetor jetting.

The first step to jetting is setting the correct float height.

Article by: Faded
"Here are a few words and some pictures I put together to help eliminate the confusion in setting your float level. Obtaining the correct float level is of the utmost importance as it can affect all jetting circuits. THE FLOAT LEVEL IS THE FIRST STEP TO PROPERLY DIALING IN YOUR JETTING. It should be checked and/or set before you even think about swapping brass. By altering the volume of fuel in the float bowl you can vary your fuel pressure and affect your jetting. More fuel in the float bowl will create more fuel pressure and result in rich(er) running conditions and vice versa.

You’ll need to first start off by removing your carb. Be sure to clean the surrounding area to the best of your ability to avoid dirt and debris falling into your carb, or worse, your engine. After you’ve removed your carb I would suggest a thorough cleaning using carb cleaner (or equivalent) and compressed air to ensure that all jets and passageways are spotless. Avoid using wire or other tools to clean orifices of jets; it’s all too easy to alter their original designed dimensions.

After your carb is clean you can now set your float level. The picture below will allow you to become familiar with the parts that are responsible for maintaining the correct float level in your carb. There are four basic parts, the floats themselves (part of the float assembly), the float assembly tang, the fuel inlet needle valve, and the fuel inlet valve seat.
Posted Image

(Float assembly pivot pin not shown.)


It is always a good idea to remove the float assembly pivot pin (already shown removed) and extract the float assembly and the fuel inlet needle. The fuel inlet needle is a wearable part and over time can deteriorate. A worn fuel inlet needle can contribute to an irregular float level. Most fuel inlet needles consist of an internal spring loaded bumper (which contacts the float assembly tang) and a plastic or Viton (rubber) tip. Inspect the fuel inlet needle tip for wear and/or damage. To give you an idea, Eric Gorr recommends replacing the fuel inlet needle/seat assembly every two years. I’ve found that the average cost it around $15 for both parts.
Posted Image

(Fuel inlet needle shown with Viton (rubber) tip. The Viton is used to isolate the fuel inlet needle from vibration and to create a better seal against the fuel inlet valve seat.)

Now that you’ve made sure you aren’t going to have any issues from worn parts you can reinstall your needle, float assembly and float assembly pivot pin and continue on to set your float level. The float level measurement is taken from the top of the floats (when the carb is positioned upside down) to the gasket surface of the float bowl as illustrated in the next picture. You can use an open-end wrench (sized per your spec), a small metric ruler, or a float level gauge. The tolerance for your float level is usually around +/- 0.50mm.
Posted Image



When setting the float level be aware that the spring loaded bumper on the fuel inlet needle valve may have a tendency to compress under the weight of the float assembly which will skew your measurement. Before you obtain your measurement you’ll need to make sure that the float assembly tang just barely makes contact with the spring-loaded bumper. Sometimes it is easier to hold the carb body at a 45-degree angle to avoid compressing the spring in the fuel inlet needle.
Posted Image



If you find that your measurement does not match your float level spec then you can carefully bend the float assembly tang to achieve your desired measurement. Be sure to recheck your work, and if you feel confident that your float level is spot on then you can reinstall your carb and get back to riding."

END OF ARTICLE


Now that you know that you have the correct float height, you can start swapping out brass.

Words of Assurance: Jetting isn't hard and comes with practice. You're not going to mess your bike up unless you make huge changes. You WILL be able to tell if your bike is running lean enough to be in danger of seizing. So, don't worry.


Article by Spanky:

"Throttle Ranges:
Pilot Jet/air screw:0-1/4.
Needle Jet:1/4-3/4
Main Jet: 3/4-Full open

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 power band. A cleanly jetted pilot circuit can be the difference between having to clutch the bike out of a turn or not. 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.

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.

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. The reason is simple. 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 rejet 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.

Before you start the jet testing, Install a fresh plug. Warm the bike completely, and shut it off.

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 airscrew 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.

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.

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.

Once you have a little bit of experience with jetting changes, and you start to learn the difference in feel between "rich" and "lean", you'll begin to learn, just from the sound of the exhaust and the feel of the power, not only if the bike is running rich or lean, but even which one of the carb circuits is the culprit.

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."

END OF ARTICLE

NOTE:
REMOVING (leaning) oil from the GAS/OIL mixture makes your AIR/FUEL mixture RICHER, effectively making your engine run RICHER (more smoking/spooge) . If you remove oil from your premix mixture, you have more gas in a specific amount of fuel. Making the mixture that really matters, the air/fuel mixture, richer. Do not fix jetting issues by changing your premix ratio.

If you guys like this little article, it would be nice if we could get this stickied in all of the two-stroke forums, to avoid the same questions being asked over and over again.

I hope this helps.
:cheers:



great job!!! how do you save this article? this alone will save me so much time tinkering with my family's 'toys'
tim
tim

  • Murphys25

    TT Bronze Member

134 posts
Location: California

Posted December 08, 2006 - 10:35 PM


To Murry with the '01 YZ: Have you checked the compression on the motor? When was the last time you did a top end? It may be that the compression is low upon initial starting (difficult) then as the cylinder and piston heat up the compression improves (starting easier). Just an idea.

  • Chokey
13,640 posts
Location: Florida
Garage View Garage

Posted December 09, 2006 - 06:05 AM


thing i see the most is operator error.....basiclly not ridding a 2 stroke correctlly.....most people have a tendency to ride in to tall of gear and not rev it out enough....so if your geting a little spoge at the end of the pipe......try riding harder first...:worthy:

Sorry, but not true. A properly jetted two-stroke will never spooge or foul plugs, no matter how it's ridden. I can rip around the track one day and putt-putt around on tight mountain trails the next day on my KX with zero spooge, ever. I hear that excuse so many times, "Ride it harder! The spooge will stop!". And yes, sometimes that will cure the spooge, because quite often bikes are jetted fairly close on the main jet but too rich on the needle and pilot. And of course riding harder will place more load on the engine, elevating combustion temperatures. But you are simply masking the problem, not fixing it.

  • dtkiko

    TT Titanium Member

2,832 posts
Location: Philippines

Posted December 13, 2006 - 07:45 AM


thanks for this outstanding tip, motocross 26! :thumbsup:

hats-off to you, mate :devil:





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Dirt Bike   General Dirt Bike Forums   What bike should I buy?
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93 yz 80 crank bearings out by Wheelierider3


Dirt Bike   Make / Model Specific   Yamaha   Yamaha 2-Stroke
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Yamaha YZ85 2015 by Bryan Bosch


Yamaha YZ85 2015
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