Question about Yamaha YZ 125 Motorcycles

1 Answer

MY 1998 YZ 125 KEEPS FOULING PLUG AND THEN BOGS DOWN

THE PLUG KEEPS GETTING WET WITH OIL AND I WIPE IT OFF AND IT STARTS BACK UP BUT BOGGS OUT I GONE THREW LIKE 5 SPARK PLUGS WITH IN 4 DAYS IT ALSO BLOGGS WHILE IM COMING DOWN A HILL

Posted by Anonymous on

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  • Yamaha Master
  • 58,537 Answers

Hi, Anonymous and the usual suspects are:
1. Fuel mixture too rich or enrichner left out too long.
2. Incorrect spark plugs for your kind of service.
3. Piston rings badly worn or broken.
4. Valve guides are badly worn and/or seals worn, crushed or have come off valve guide and pump oil through it.
5. Spark plug cable weak or ignition coil faulty.
For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
Why Does My Dirt Bike Keep Fouling Spark Plugs
Fouling plugs in my yz 125
YAMAHA YZ125 Owner Service Manual
OEM parts for Yamaha
http://mybikemanuals.com/yamaha/yamaha-yz-owners-manuals

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

Posted on Jul 17, 2016

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6 Suggested Answers

6ya6ya
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SOURCE:

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Posted on Jan 02, 2017

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  • 46 Answers

SOURCE: spark keeps fouling but no clue why

Are you losing gear oil.
When the crankshaft seal leaks, oil from the gearbox is sucked into the crankcase, and this can foul the plug.
Also check the plug gap, most guys set the gap too small. It should be 0,7mmto 0,8mm. The plug should be a B9 EG, or equivilant.
Now, you can also change the plug cap to a type that has a built in resistor, this also helps with plug life.
Note that 2 strokes use plugs way more than 4 strokes, and you should replace the plug every 15-20 hours to keep your riding pleasant.
Good Bike you have there
Cheers
Jon

Posted on Feb 16, 2009

  • 46 Answers

SOURCE: yamaha yz 125 2001.water leak

Yes, the water seal is leaking. This is the indicator hole for the water and oil seal.
Enjoy the ride !

Jon

Posted on Mar 01, 2009

  • 3567 Answers

SOURCE: Fouling plugs

Get a new NGK spark plug one heat range hotter than stock. Be sure the fuel mix is 32/1 using two stroke engine oil ( not motor oil ). A 32/1 mixture equals 4 ounces oil to 1 gallon of gas. Remove the cylinder head and de-carbon the top of the piston and head.

Please rate this solution. Thanks!

Posted on Apr 07, 2009

  • 44 Answers

SOURCE: what spark plug for yz 125?

I have a dennis kirk book, the correct spark plug is a --BR9ES--(NGK)

i always used SAE 10w-30 oil on all my dirtbikes,
no transmission fluid

for the chain you should move the back tire back until the chain is at a snug tension

Posted on Apr 24, 2009

wayneman01
  • 301 Answers

SOURCE: my yamaha yz 125 is dumping to much fuel and

There are only two adjustments to make on your carburetor; the idle speed, and the idle mixture adjustment. If the spark plug fouls frequently, first make sure you are using the correct spark plug. Your 1997 YZ125 uses an NGKB9EGV. Then be sure you are using the recommended two stroke oil, mixed to the proper ratio, in the fuel. Also make sure the air filter is not excessively soiled.
With all of the above confirmed and corrected, start the bike and run until the engine is up to normal temperature. Adjust the idle mixture screw to attain the fastest idle and best throttle response. Then adjust the idle speed.
If you are still fouling the spark plug, verify that the carburetor has the correct size jets by consulting your owner's manual. Keep in mind that if you are operating your bike at an altitude higher than about 6,000 feet above sea level, the stock jetting may be too rich. Down-size the main jet in small increments until satisfactory operation and the correct spark plug color is obtained.

Posted on Nov 02, 2009

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1 Answer

Yz 125 fouls spark plug when it bogs.


Hi, Anonymous and the usual suspects are:
1. Fuel mixture too rich or enrichner left out too long.
2. Incorrect spark plugs for your kind of service.
3. Piston rings badly worn or broken.
4. Valve guides are badly worn and/or seals worn, crushed or have come off valve guide and pump oil through it.
5. Spark plug cable weak or ignition coil faulty.
For more information about your issue and valuable "FREE" downloads that you will need please click on the links below. Good luck and have a nice day.
http://www.woodsracer.com/portal/forums/showthread.php?6812-YZ-125-Help!!!-Fouling-plugs!!!
Fouling plugs in my yz 125
Yamaha YZ125N1 Service Manual
OEM parts for Yamaha
http://mybikemanuals.com/yamaha/yamaha-yz-owners-manuals

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

Oct 20, 2013 | Yamaha YZ 125 Motorcycles

1 Answer

Yz 125


If the plugs are fouling from excessive oil then it may be that the oil ring is broken. That will be scoring the bore and accounting for the low compression pressure. To do compression checks the motor has to be hot and the throttle wide open. Check for blocked filter before testing. IN the short term run a hot plug . ( where the porcelain insulator is very long in the plug) as this will help it burning off the oil .

Apr 28, 2013 | Motorcycles

1 Answer

My yz 125 starts first kick but when im ridding it it wont give full power im getting some smoke and some black oil can you help not been into bikes long


you might want to check your air filter first .. mine was doing the same thing ,.. and i checked the air filter and it was covered in oil so it wasnt getting enough air when i tried to take off ,.. if the air filter looks good , you may want to pull your spark plug and look at it ,.. if it is covered in black it is time for a new one .. or a really good cleaning ,.. i found a wire brush and penetrating oil works well ,.. blow it out with compressed air and wipe off all that you can before you stick it back in ,... other than those i hear the rings are only good for about 20 hours (non-racing)
thats where i would check next ,.. let me know if this helps =D

Aug 18, 2011 | 2003 Yamaha YZ 125

1 Answer

My 2003 Suzuki rm 125 kick starts with brand new spark plug then eventually bogs down and dies, does the same when push started, does it need new piston and rings?


HI,,sounds like your plug is fouling,,what pre-mix ratio are you running? and has the carb been played with? run 32-1 premix and remove and clean the carb.

piston and rings are not to blame for this behaviour.

Mar 23, 2011 | 2003 Suzuki RM 125

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

Fouling plugs


This can be caused by all sorts of things.There is no real order of probability so I'll just list them.Your oil/fuel ratio could be rich depending on what oil you use,your powervalve could be stuck closed(pop off the plastic cover over the actuator located at the front of the clutch cover,its held in place by 3 screws attached to the barrel,start the bike and give it a big blat on the throttle and see if the lever moves)it could have a blown crank seal(the symptom displayed by this fault is that you will be using gearbox oil),the expansion chamber could be carboned up,or the piston and/or rings could be worn.If all these things check out ok I suggest either raising the clip on the needle(which drops the needle causing the mixture to run slightly leaner) If this does not have enough effect go down one size in the main jet.Adjusting the main jet size will require you initally to very frequently remove the spark plug to check that you haven't gone too lean. The plug should not be wet and oily,the perfect colour is a tan colour and not wet.I must stress that jetting a 2 stroke if you lack experience can be tricky in that if you go too lean you can seize the engine so if you do reduce the size of your main jet frequent initall inspections of the plug is highly recommended.As a final note,if you are using a standard plug and not a racing plug(ie gold paladnium or irridium)thay are inherently more susseptable to fouling & changing to a "racing plug" may help to reduce your plug fouling.Hope this was helpfull

Nov 22, 2009 | Yamaha YZ 125 Motorcycles

2 Answers

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?


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.

Oct 27, 2009 | 2003 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

1 Answer

My 01 yz 125 is running really strange


your problem sounds common. i would also try a rejet!

Apr 07, 2009 | 2003 Yamaha YZ 125

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