Question about 2003 Yamaha YZ 125

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2003 Yamaha 125 yz plug fouls pretty quickly. running 32/1 fuel oil ratio, and using NKG plug 2411/B8ES. Do we need to run a hotter plug?

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Like he said BR8EG runs hotter for yamahas and is bettter because br9eg foul quickly. Use castro in 2 stroke bikes. It runs a little higher because its better

Posted on Nov 17, 2009

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NGK BR9EG is the stock plug for your bike. You are one heat range hotter already. I suggest you go to a BR8EG to keep you in the racing plug style but one range hotter than stock. I question what 2 stroke engine oil you are using. Stick with Yamalube 2 stroke oil and you should be okay. If you are using standard motor oil like you have in the gearbox then the fouling is definitely the oil.

Posted on Oct 27, 2009

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1 Answer

Why does my dirt bike keep fouling plugs


Hi, Joey assuming it's a 2 stroke the usual suspects are:
1. The first thing to do if your spark plug has been fouled is to check the air filter. If it's really dirty, that makes it difficult for air to get through to the engine, causing a rich condition. Either clean it thoroughly with some Air Filter Cleaner or buy a new filter. Before you put it back in the air-box, treat with a fine mist of some air filter oil or spray. "WARNING" adding too much oil can also clog up the filter, resulting in another fouled plug.
2. While the gas/oil ratio doesn't equate to what the jetting is, you can still foul plugs, or worse, if the mixture is wrong. Depending on your bike, it's best to look at your owner's manual for the correct ratio. For most 2-stroke motocross bikes, a ratio is 32:1 or 40:1, the gas being 32 or 40, and oil being 1. For those that don't it, it means that for every 128 ounces (one gallon) of gas, you add 4 ounces of 2-stroke oil for a 32:1 ration, or just over 3 ounces for a 40:1 ratio.
If you have too much oil in the mixture (such as 12:1), then you will probably end up fouling the plug because it is more difficult to burn that much oil. Don't try to cut corners with the oil though, because it's very important for your dirt bike's engine. 2-stokes need the oil for lubrication on the cylinder walls, so if you don't have enough (or any for that matter) then the cylinder walls will run dry, causing it to overheat and seize the engine very quickly. So it's very important that you put in the right mixture pre-mix to your 2-stroke gas tank.
Also, 2-strokes have reeds that air and fuel go through into the cylinder, so if they are cracked or broken the bike will not run right. This could cause the plug to foul, so before you go out and buy anything expensive, make sure the reeds are in good condition.
3. While this usually isn't the main problem, it could be that your spark plug isn't burning hot enough. Having a hotter spark will ignite the fuel stronger, leaving less residual gas/oil in the cylinder that could cause the plug to foul. This "ISN'T" the best choice, but I'd say it's safe to go one plug hotter than stock. Keep an eye on the plug color you're looking for a light tan color anything whiter and you could burn a hole in your piston. Spark plug manufacturers aren't always the same, so make sure you find out how they rate them.
4. Almost every motocross bike comes rich from the factory (especially Honda 2-Strokes when they were being made). It's usually a pretty simple fix, but many riders are too lazy and would rather continue buying plugs instead of spending a few bucks on jets.
5. Piston rings badly worn or broken.
6. Faulty ignition coil low output.
For more information about your question and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
Fouling plugs in my yz 125
Spark Plugs Keep Fouling
why does 2 stroke foul plug
fouling plug with 4 stroke what wrong ATVConnection com ATV Enthusiast...
How do you stop plug fouling

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

Jun 06, 2017 | Motorcycles

1 Answer

2003 Kawasaki KX 250 keeps fouling spark plugs


Hi, Nicholaswink and the usual suspects are:
1. The first thing to do if your spark plug has been fouled is to check the air filter. If it's really dirty, that makes it difficult for air to get through to the engine, causing a rich condition. Either clean it thoroughly with some Air Filter Cleaner or buy a new filter. Before you put it back in the air-box, treat with some air filter oil or spray. "WARNING" adding too much oil can also clog up the filter, resulting in another fouled plug.
2. While the gas/oil ratio doesn't equate to what the jetting is, you can still foul plugs, or worse, if the mixture is wrong. Depending on your bike, it's best to look at your owner's manual for the correct ratio. For most 2-stroke motocross bikes, a ratio is 32:1 or 40:1, the gas being 32 or 40, and oil being 1. For those that don't it, it means that for every 128 ounces (one gallon) of gas, you add 4 ounces of 2-stroke oil for a 32:1 ration, or just over 3 ounces for a 40:1 ratio.
If you have too much oil in the mixture (such as 12:1), then you will probably end up fouling the plug because it is more difficult to burn that much oil. Don't try to cut corners with the oil though, because it's very important for your dirt bike's engine. 2-stokes need the oil for lubrication on the cylinder walls, so if you don't have enough (or any for that matter) then the cylinder walls will run dry, causing it to overheat and seize the engine very quickly. So it's very important that you put in the right mixture pre-mix to your 2-stroke gas tank.
Also, 2-strokes have reeds that air and fuel go through into the cylinder, so if they are cracked or broken the bike will not run right. This could cause the plug to foul, so before you go out and buy anything expensive, make sure the reeds are still good.
3. While this usually isn't the main problem, it could be that your spark plug isn't burning hot enough. Having a hotter spark will ignite the fuel stronger, leaving less residual gas/oil in the cylinder that could cause the plug to foul. This "ISN'T" the best choice, but I'd say it's safe to go one plug hotter than stock. Keep an eye on the plug color you're looking for a light tan color anything whiter and you could burn a hole in your piston. Spark plug manufacturers aren't always the same, so make sure you find out how they rate them.
4. Almost every motocross bike comes rich from the factory (especially Honda 2-Strokes when they were being made). It's usually a pretty simple fix, but many riders are too lazy and would rather continue buying plugs instead of spending a few bucks on jets.
5. Piston rings badly worn or broken.
6. Faulty ignition coil low output.
For more information about your question and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
KX 250 Fouling plugs PLEASE HELP
2003 KX250 killing plugs not fouling
https://www.howtomotorcyclerepair.com/images/Kawasaki-KX-125-KX250-Service-Manual-2003-2004-2005-2006-2007-2008.pdf
OEM Parts for Kawasaki
2003 Kawasaki KX250 Owner Manual

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

Jun 27, 2012 | 2003 kawasaki KX 250

1 Answer

Plugs-keep-fouling-tried-3-different-plugs-what-can-i-do-to-solve-this-problem


What is causing the fouling? Engine oil? On a two cycle dirt bike, the fouling can be caused by excessive oil in fuel mix. I believe 50 to 1 is the correct ratio yet you may want to cut back, a little at a time, on the oil or run hotter fuel. The exhaust system will also accumulate enough oil sludge to impede the exhaust flow causing poor performance and plug fouling. A two cycle must breath freely to keep itself internally clean. Air cleaner to exhaust. Proper fuel mix should have little , very little. Good Luckand hopefully this helps you.

Dec 27, 2010 | 2003 Yamaha YZ 125

1 Answer

2005 Kawasaki KX 125 spark plug keeps fouling


Hi, Molokaiboy96 and the usual suspects are:
1. The first thing to do if your spark plug has been fouled is to check the air filter. If it's really dirty, that makes it difficult for air to get through to the engine, causing a rich condition. Either clean it thoroughly with some Air Filter Cleaner or buy a new filter. Before you put it back in the air-box, treat with some air filter oil or spray. "WARNING" adding too much oil can also clog up the filter, resulting in another fouled plug.
2. While the gas/oil ratio doesn't equate to what the jetting is, you can still foul plugs, or worse, if the mixture is wrong. Depending on your bike, it's best to look at your owner's manual for the correct ratio. For most 2-stroke motocross bikes, a ratio is 32:1 or 40:1, the gas being 32 or 40, and oil being 1. For those that don't it, it means that for every 128 ounces (one gallon) of gas, you add 4 ounces of 2-stroke oil for a 32:1 ration, or just over 3 ounces for a 40:1 ratio.
If you have too much oil in the mixture (such as 12:1), then you will probably end up fouling the plug because it is more difficult to burn that much oil. Don't try to cut corners with the oil though, because it's very important for your dirt bike's engine. 2-stokes need the oil for lubrication on the cylinder walls, so if you don't have enough (or any for that matter) then the cylinder walls will run dry, causing it to overheat and seize the engine very quickly. So it's very important that you put in the right mixture pre-mix to your 2-stroke gas tank.
Also, 2-strokes have reeds that air and fuel go through into the cylinder, so if they are cracked or broken the bike will not run right. This could cause the plug to foul, so before you go out and buy anything expensive, make sure the reeds are still good.
3. While this usually isn't the main problem, it could be that your spark plug isn't burning hot enough. Having a hotter spark will ignite the fuel stronger, leaving less residual gas/oil in the cylinder that could cause the plug to foul. This "ISN'T" the best choice, but I'd say it's safe to go one plug hotter than stock. Keep an eye on the plug color you're looking for a light tan color anything whiter and you could burn a hole in your piston. Spark plug manufacturers aren't always the same, so make sure you find out how they rate them.
4. Almost every motocross bike comes rich from the factory (especially Honda 2-Strokes when they were being made). It's usually a pretty simple fix, but many riders are too lazy and would rather continue buying plugs instead of spending a few bucks on jets.
5. Piston rings badly worn or broken.
6. Faulty ignition coil low output.
For more information about your question and valuable "FREE" downloads that you will need for viewing or printing please click on the blue links below. Good luck and have a wonderful day.
2003 kx125 fouling plugs
Spark Plugs Keep Fouling
https://www.howtomotorcyclerepair.com/images/Kawasaki-KX-125-KX250-Service-Manual-2003-2004-2005-2006-2007-2008.pdf
OEM Parts for Kawasaki
2005 Kawasaki KX125 Owner Manual

Btw, I’m available to help over the phone in case u need at https://www.6ya.com/expert/gregg_c0ec1df182c7330e

Jul 28, 2010 | 2005 kawasaki KX 125

2 Answers

What spark plug should i run in my 2003 YZ 125?


Run a B9ES if you don't have a problem with fouling. If you do have a problem fouling, run a B8ES. Both of these plugs are available at auto parts stores for a few bucks each.

The stock plug was a BR9** - the R indicates a resistor plug which is not needed.

Scott

Jun 18, 2010 | 2003 Yamaha YZ 125

1 Answer

Fuel ratio 2 stroke yahama YZ125


32:1--40:1 Any less than a 32:1 mix and she will smoke and foul plugs(not to mention wasting money on mix) Any more than a 40:1 mix and your top end ect. is not being lubed enough which will lead to costly top end and engine repair..... 40:1 is good for a synthetic mix...And 32:1 for a non synthetic mix.... hope this helps ya....

May 21, 2010 | 2003 Yamaha YZ 125

1 Answer

My bike keeps fouling my plugs i got a 2003 yamaha yz 125 i chucked a br8eg plug init and a new air filter but the problem just wont go away


Two things could be at fault here. First - it's a good possibility you would benefit from a new top end. Top ends go away fast in these because they are single ringers. Under hard riding, the compression starts to fall off after just 2 hours. Poor compression means lower combustion temperatures which will lead the bike to run rich.

The other possibility is that your jetting is off. If you have had this bike for a while and it's always run well then slowly started to act up, its likely poor compression, but if you recently got this bike and do not know the history of it, then it could be a simple jetting issue - not at all uncommon for 2-strokes.

Also - no need to run the BR8EG. This is a resistor plug and is a higher performance plug. If you are a top Pro rider, you could feel the difference but for 99% of riders they could not tell the difference between a BR8EG and a B8ES. The B8ES is readily available from auto parts stores (NGK stock #2411) for $1.89 instead of $12+ for a EG plug form a bike shop. This info alone could save you a bunch of money. Keep in mind the stock plug is BR9EG, so you are running one step hotter which is fine.

Also keep in mind there is a lot of information that I do not know, nor do I know the overall condition of the bike. Internet diagnosis is always tricky, but I thought I would point these things out. I hope this has helped, but if not - we need more detailed info to properly diagnose the problem.

Feb 09, 2010 | 2004 Yamaha YZ 125

2 Answers

2000 yz125 keeps on fouling out plugs


Fouled plugs are typically caused by jetting that is too rich. This could also be from a dirty air filter which can make the bike run rich. Clean up your filter and see if that is it. If the filter is not too bad, you might want to drop a size on your pilot or main.

Another possibility is poor compression - this can make a 2-stroke run richer than normal as the fuel can not be burned properly. Rings don't last long in these 125s. I used to re-ring each week when I was racing 125s.

You might want to run a B8ES plug, too - this is one step hotter and will help the plug from fouling as often.

Feb 01, 2010 | 2004 Yamaha YZ 125

2 Answers

Oil and gas mixture coming out by exhaust


first off make sure the oil gas mixture is correct and mixed very well.... have the carb cleaned out very well or even rebuilt, jetted and adjusted...

Jul 06, 2009 | 2003 Yamaha YZ 125

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