Question about 2004 Yamaha YZ 125

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Weak spark on 1993 yz 125 - 2004 Yamaha YZ 125

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  • Yamaha Master
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Hi, Anonymous there is no such thing as a weak spark even though dozens of riders will swear that's what they have and are dying to show you, the bottom line is either you have spark or don't have spark there is no in between.
You won't see a dirtbike spark really well, and people only look at it when they have a problem. It is designed to fire under extreme pressure (13:1 compression) and is very robust, but it is not a 1mm bright blue line jumping across a spark plug. It can be white and very hard to see. If you are confident you have weak or no spark prove it by holding the plug in your hand and stark kicking you will be in for a "SHOCKING" surprise!!!!!
60% of these bikes have a flooding issue and/or a fouled plug. 30% need valves adjusted and most of the remaining 10% are something simple in the electrics like a broken kill switch, bad earth on the battery or dead battery, wiring at the steering head damaged or blown fuse.
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.
Yamaha yz125 won spark
How to fix No Spark Problem on Motorcycles and Dirt Bikes
Yamaha YZ125T1 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 Apr 23, 2017

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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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FoRdMaStEr
  • 53 Answers

SOURCE: 1997 yz 125 wont start, please help

2 stroke bike are very dependent on compression. and being a bike that is 12 years old my best educated guess is that the top end needs to be rebuilt. i usually have to have the top end done on my honda about every three years.

Posted on Jan 13, 2009

tabbycat282
  • 56 Answers

SOURCE: 1999 yz 125 weak spark won't start

Not much info Smitty but if that weak spark is constant (ie:pulsing ) i would guess that the trigger coil is ok.I'd make a check on your ignition coil earths then do a couple of continuity tests on your coil primary and secondary , orange terminal to ground,orange terminal to ht lead ,if they check out ok according to service manual specs then i'd run continuity test on the source coil.....Hope this is helpful in someway ...Smittycat.......from Flabbycat

Posted on Apr 19, 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

  • 3567 Answers

SOURCE: how do i decode yamaha yz 125 engin id number

You don't decode it. It is only a production run series number. Mororcycles are like cars in that respect. It is the frame number, AKA the "VIN number", is what carries all the information. Call a dealer with the frame number and he can tell you year, paint color, specific model and more. They may have a problem if the bike is too old. Yamaha changed to a newer code system a few years back.
Can I get a “very helpful” rating on this answer?

Posted on Aug 28, 2009

dmsr63
  • 2050 Answers

SOURCE: yz 125 1990 clutch spring diagram

www.bikebandit.com
It's one of the few that has a diagram.
Not sure what you mean by anti-rattle? The springs are for the pressure plate, and allow the clutch to grab, so you can go.

Posted on Sep 13, 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

MY 1998 YZ 125 KEEPS FOULING PLUG AND THEN BOGS DOWN


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

Mar 18, 2013 | Yamaha YZ 125 Motorcycles

2 Answers

My yamaha yz 125


if your getting spark than i would take the carb off and clean it you could have a cloged jet.( just because your getting fuel from tank to carb dont mean its getting from carb to jug) i would try that first......yz-maniac.

May 14, 2010 | 2004 Yamaha YZ 125

1 Answer

I have a yamaha yz 125 1994. I have a problem with a weak spark.. i thought it was the stator but when we applied a volt check there was 12 on the stator. but as we go up to the coil there is less and its...


it will be the coil buddy what you can do is try the coil off the lawnmower on the bike but just to test it as you will lose performance if kept on there

Sep 30, 2009 | 2003 Yamaha YZ 125

1 Answer

Weak spark


If there was a probem with the coil the extra loading from the short circuit may have caused a problem with the trigger coil for the main coil. I don not have the spec but this value can be check with an ohm meter. Let me know how you make out...

Sep 25, 2009 | 2003 Yamaha YZ 125

1 Answer

2007 125 yz, has a miss before the power valve kicks in. short flat spot then , have keep the revs high to avoid it!!


There's no extra valve that kicks in to give the bike extra power. The term "power band" is simply referring to the RPM range of the motor that produces the most torque. Make sure the carb is clean and check the spark plug gap and fire. You need a hot blue,purplish fire not a weak white looking fire. If the plug itself is whitish in color you need to richen up the carb if it's black you'll need to lean it out. You should have a chocolate almond color. I'd bet the bike is getting too much air.

Aug 24, 2009 | 2003 Yamaha YZ 125

2 Answers

2000 YZ 125 Breaks up at High RPM. We think its the power valve. any tips would be great


check fuel float level as it might not be able to keep up the flow rate at those revs
or the read valve has become weak

Jul 19, 2009 | 2003 Yamaha YZ 125

1 Answer

My 2003 yz 125 hesitates when you give it gas.It does it every time you switch gears.You have to give alot of gas to straighten it out.


it is one of a few things causing it to flail in the lower end, 1: your fuel oil mixture isnt lean enough.. 2: you need a higher spaking plug.. 3: your carburetor float level is out or 4: there is a slight break in the ignition spak line which would cause it to spark very weak until maximum accelleration is reached

Jun 03, 2009 | 2003 Yamaha YZ 125

1 Answer

Yz 125cc 2003


Black spark plug means too rich , you will have to replace the spark plug since it has foul up and reset the air mixture screw on the carburator 2 and 1/2 turns outwards.
Check the air filter too.
Hope this helps.

May 23, 2009 | 2003 Yamaha YZ 125

1 Answer

1999 yz 125 weak spark won't start


Not much info Smitty but if that weak spark is constant (ie:pulsing ) i would guess that the trigger coil is ok.I'd make a check on your ignition coil earths then do a couple of continuity tests on your coil primary and secondary , orange terminal to ground,orange terminal to ht lead ,if they check out ok according to service manual specs then i'd run continuity test on the source coil.....Hope this is helpful in someway ...Smittycat.......from Flabbycat

Apr 19, 2009 | 2003 Yamaha YZ 125

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