Question about 2005 Honda CR 125 R

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Spark keeps fouling but no clue why

The spark blug keeps fouling but the oil mixer is fine just the spark plug gets real oily and only funs for bout 20 then fouls

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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

Posted on Feb 16, 2009

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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.
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Mar 18, 2013 | Yamaha YZ 125 Motorcycles

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I put too much oil in 06 yamaha r6 raven and its not starting

Hello.....sometimes when you overfil the crankcase..the engine develops high pressure and the gaskets will fail...or in your case...the excess oil will make it's way into the combustion chamber and foul your spark plugs...The first thing you need to do is drain the excess oil...and get it down to the proper level...Then take out the spark plugs..if they are black and oily...clean or replace them......Then try to start it....If it will smoke fo a while as it burns off the oil in the combustion chamber...then it should be fine...Be careful no to over fill the engine again....Let me know what happens...I hope this was helpful....PEACE.....

Mar 08, 2012 | 2006 Yamaha YZF-R6

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So i was wondering i changed the spark plug on my bike including all oils, also included a costume yamaha fuel filter bike started fine rode it. Than second time i started it i forgot to turn gas line...

hi, the problem is that your bike is running to rich( to much fuel from carb to engine) so its the un-burned fuel mix that your seeing on your plug and thats fouling it this is caused by either to rich of fuel mixture(you should be mixing 32:1) or you need to rejet carb so it delivers less fuel to engine... your carb has a jet in it and the # is stamped on it ( if you take the carb off and remove the bowl( 4 screws) you will see it,it will have an octagon shaped head.) for example if the # on it is 55 then you need to go with a 53 or 54...... also a good sign you need to rejet with a smaller jet is your bike will spooge(leak) a black oily residue from exhaust pipe and muffler( same residue thats fouling the spark plug.)

Sep 27, 2010 | 2003 Yamaha YZ 125

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There is unnecessary noise when the engine is running and hard to start, the spark plug is always wet like an oil

As for the noise in the engine, could be alot of things. If your plug is very oily, then it's probably fouled. That would make it difficult to start & possibly run rough. Pretty common with 2 strokes. Sounds like your mixture on your fuel has too much oil in it when you mix it. Make sure you're mixing your fuel properly then I would check on rebuilding and adjusting your carb if your fuel mix is right. Hope this helps

Sep 15, 2010 | 2003 Yamaha YZ 125

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How do I check spark plugs?

norm - brown grayish-tan deposit on side electrode.
carbon fouled - black, dry fluffy soot on insulator tip and electrodes
oil fouled - wet, black, oily deposits on " " " "
burned - blisters on insulator tip, and electrodes
worn - severely erroded or worn electrodes

May 31, 2010 | 2006 Buell Lightning XB12S

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I have a 2002 fxd dyda which misses and backfires.i have put new plugs and leads on which helps at first but after a couple of weeks it happens again.any ideas please?

You're going to have to look at what your plugs look like when you take them out. If they look really black and sooty, or black and oily, they're probably fouling. If they're oily looking, you are getting oil into your combustion chamber from somewhere, probably valve stem seals. This is very rare.

Now, if they're very black and sooty looking, your mixture is too rich or you're letting your engine run with the enricher in the "on" position for too long. The "too rich mixture" will mean either a carb problem or a computer setting if it's fuel injected. The bikes usually come set extremely lean from the factory so someone has either changed the jetting, there's something wrong with either the carb or computer settings.

If you allow the engine to "warm up" too long with the enricher out, it will foul spark plugs. I usually start the engine and let it run with the enricher out just until I can keep it running with the throttle. At that point, I turn the enricher off. I hope this helps. Good Luck

Mar 10, 2010 | 2002 Harley Davidson FXD Dyna Super Glide

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

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