Question about 1978 Honda GL 400

3 Answers

I have a 78Gl1000 the #2 plug fouls very quickly. No oil on the plug, the color is a dark gray. I have put 3 different set of carbs of the last 6 years, new gas tank, new solenoid had the valves adj and the psi in the pistons checked 165 165 165 170 new points, idle perfect, no smoke other than the initial start which is classic of these bikes

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  • cmccrater Sep 06, 2010

    I have a Honda 1978Gl1000 the #2 plug fouls very quickly. No oil on the plug, the color is a dark gray. I have put 3 different set of carbs of the last 6 years, new gas tank, new solenoid had the valves adj and the psi in the pistons checked 165 165 165 170 new points, idle perfect, no smoke other than the initial start which is classic of these bikes. Could there be a chance that the exhaust valve is not closing all the way and allowing carbon back into the chamber on the intake stroke. And if so wouldn't that show up on the compression test>

  • cmccrater Sep 07, 2010

    The only problem is that it's a horizontal motor and the other 3 cylinders don't have this problem and all 4 cylinders get their fuel from the same carb

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Dark grey color and deposits means that you have a small amount of oil burned, most likely coming from the valves since the compressions are just fine. The fouling aka deposits on the plug are caused by the additives - replace the oil and gas brands, apparently they are incompatible.

Posted on Sep 07, 2010

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It sounds like you have went through the whole process. I dont see where you checked or changed the fuel system delivery. If it is
pumped it is most likely fuel fouling plugs. If the fuel mixture is too
rich or too lean then the plugs are fouling due to that.

Posted on Sep 07, 2010

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  • frank thomas wilson
    frank thomas wilson Sep 06, 2010

    I do hope the you tube explainations helped you out somewhat resolving the plug issue

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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.
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1 Answer

Bike sat up for 3 or 4 years. recently cleaned the carb, changed the plug and oil and bike started. Tried starting it recently and it wont. Seem to be backfiring sometimes when kicking it over.


clean plug .. although new plug if old fuel or unbalanced carb it may quickly foul. if this works you may need help to work out whats causing plug to foul.

Mar 10, 2013 | 2001 Yamaha YZ 426 F

1 Answer

Help with 76 ironhead 1000 fouls plugs when it get hot and it wont charge


Ok, you have two problems. Fouling plugs and charging system problems. Work with one problem at the time. I'd work on the plug fouling problem first. What is fouling the plugs? Is it oil or gasoline fouling the plugs. Take one of the fouled plugs out and smell of it. Is it gasoline or oil fouling the plugs? If its gasoline, you have a problem with the carburetor. In this case, I'd need to know what kind of carb is on the engine. Is it the original Keihin or has someone put an aftermarket carb on the engine? Do you know how to check the jet sizes in the carb? If it's oil fouling, is it due to valve guides or rings? Does the engine smoke from the tailpipes? What color is the smoke? Black or blue smoke is caused by a too rich fuel air mixture. White smoke is oil burring.

As for your charging system, the first thing to do it to polarize the generator by momentarily shorting the positive battery post with the armature of the generator. If the generator still does not charge, you need to check the brushes in the generator and the output of the generator.

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1 Answer

I bought a 92 fzr 600 ride it for a month no problem. But now it keeps popping the resistor in the spark plugs. 3 sets of plugs in the last 2 weeks. Last set lasted 2 days. All have been ngk.


NGK plugs dont stop, especially all at once, so there is another problem.
There are some resisters in the plug caps that can fail.
Are the plugs carbon fouling?(dry black) if so make sure the air filter is new, and oil is changed.
Does the enginge blow smoke or use oil?(wet black)oil fouled may mean rings.
Fuel fouled may mean the jettting is wrong or choke stuck open
Its the battery good(new) and charging ,put a multi meter across the terminals 12v stopped, 14v running approx.
it always helps to drain the carb bowls every few weeks
If exhaust is not standard, the jetting may be wrong.
does the fuel tap work correctly? only use the run or res positions never pri
A short in the kill switch or a worn ignition switch can cause a miss or backfire

May 28, 2011 | 1992 Yamaha FZR 600

1 Answer

2002 yamaha 1200 vmax 4 bbl carb fouling plugs


Hi, Jamie12r and the usual suspects are:
1. Dirty air filter.
2. Fuel mixture too rich or enrichner/choke left out too long.
3. Faulty spark plug.
4. Incorrect spark plug heat range for the engine type or service.
5. Piston rings badly worn or broken.
6. Valve guides are badly worn and/or seals worn, crushed or have come off the valve guide and are pumping oil through it.
7. Spark plug cable weak or leaking check for spark jump in the dark.
8. Faulty ignition coil.
9. Low RPM nonaggressive riding style.
For more information about your issue and valuable "FREE" downloads that you will need please click on the blue links below. Good luck and have a wonderful day.
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1 Answer

It's flooding how can i fix it


Basics to check:
1) Spark plug - brown or dark brown - OK
a) is it carbon or fuel fouled
b) is there spark

2) Muffler remove for inspection
a) exhaust screen clean or plugged
b) inspect cylinder wall/piston as the flywheel is slowly rotated
3) Check cylinder compression


Overfuel or 'rich' condition
Basics to check:
1) Spark plug - brown or dark brown - OK
a) is it carbon or fuel fouled
b) is there spark

2) Muffler remove for inspection
a) exhaust screen clean or plugged
b) inspect cylinder wall/piston as the flywheel is slowly rotated
3) Check Air filter for fuel saturation
4) Allow engine to run for 5 minutes remove to excess fuel from muffler
5) Fuel mixture ratio: Make sure the oil mix is per your manufactures recommendations
6) If after the above the engine is still smoking and blubbering:
Adjust carb mixture screws to a 'less rich' setting
*NOTE: only move mixture screws 1/8 of a turn at a time,
and try operation before any more adjustment

Nov 26, 2009 | Husqvarna 155bt Gas Backpack Leaf Blower

1 Answer

How do i set the carburetor on a Stihl FS-55 weedeater.


Over the past 8 years, the FS55 has had at least 5 different carburetors, and they have at least 3 different systems with different adjustments. Many of them do not have much of an adjustment and will not cure running problems. If you are experiencing poor running conditions, I would suggest some basic checks first. The spark arrestor screen is a big culprit on this model.

Basics to check:
1) Spark plug - brown or dark brown - OK
a) is it carbon or fuel fouled
b) is there spark

2) Muffler remove for inspection
a) exhaust screen clean or plugged
b) inspect cylinder wall/piston as the flywheel is slowly rotated
3) Check cylinder compression

Fuel starvation - 'lean fuel' condition
Basic things to check:
1) spark plug
2) spark arrestor in muffler
3) fuel lines and tank filter
4) turn adjustment needles out (counterclockwise) 1/4 to 1/2 turn
Chain Saws:
5) check impulse tube and intake boot for cracks or leaks
*if all of the above are OK and/or do not improve performance then:
Remove Carburetor
6) replace gaskets/diaphragms
a) use a spray carb cleaner to clean jets, holes, and body of carb
b) fuel pump diaphragm goes against the carb body,
then the gasket towards the outside
c) metering gasket goes against the carb body,
and the diaphragm goes towards the outside

Nov 23, 2009 | Garden

1 Answer

I have a 1978 mercury outboard 150 HP motor that run fine except when on full throttle it seems to loose power for a second then picks up again then looses power for a second then picks up again, what...


For the DIY boater it could be a number of possibilities - fouled plugs, old fuel, improper air fuel mixture or dirt in the carburetor.

Pull the plugs and check the color of the ceramic. Light tan is good. Dark and oily is an indication of misfiring, fouling and too rich oil or improper air mixture. Make a note of which plug came from which cylinder. If they're all about the same color (dark) replace them all. Properly set the electrode gap and install the plugs.

You could try spraying the intake with carb cleaner like "Gum Out"
to clean out the carbs too.

Drain and clean out the sediment bowl of the carb(s) test again.

If cleaning sdoesn't take care of the problem then you need to Reference a Mercury marine manual for initial air screw mixture settings, ie: air screw location and how many turns out are recommended.

Air fuel mix is adjusted by a screw on each carb. No more than a 1/4 to 1/2 turn should be made at a time. Test again.

Also when you store the motor for the season, get some "Gas Stabilizer" for the fuel tank. Mix the recommended amount in a full tank of fuel, run the motor for several minutes. This step will put the stabilized fuel into the carbs for storage.

Hope this helps.




Oct 03, 2009 | Boating

2 Answers

Failed spark coils on my 1999 Lexus ES 300. Replaced one last March and two more last month. I read that fouled plugs could cause coil failure. Since the recommended schedule for ''hard driving...


exposure to heat, weather,salt in winter and water make them more susceptible to failure I would change them knowing that my others failed

Aug 25, 2009 | 1999 Lexus ES 300

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