Maintenance & Technical > KX500 Original
Help smashed or melted spark plugs
Hillclimb#42:
I see. Looking for a lean condition. Super lean condition. Plug wouldn't be white or green? Hmmm, timing. Easy to check that. Is there any way its melting plugs? Its designed to be in the combustion chamber all the time. I melted a piston and rings ( brand new ) in a super lean-out deal, plug was fine. Now I'm interested to hear what it is.
Let's hear how to make a home-made leak down tester then, BDI.
BDI:
This is the spark plug out of the bike I'm working on right now. It's not a very good picture but if you look close you will see the gap is closed. The second picture is of the the piston that almost has a hole clear through it. The cause of this was the fact that the oil injection line came off of the intake and let air in. This caused a lean condition that caused the engine to start detonating. The lean condition made the spark plug so hot the electrode became soft and then the detonation did the mechanical work of closing the gap.
When an engine has a failer you have to treat it like a crime scene. You have to start collecting evidence to find the culprit. Leak down testing is one very helpfull crime fighting tool. If you do not figure out why the engine failed it is very possible you will rebuild the engine only to have it blow up again. When your engine blows up because of a bad main seal and you stick $500.00 into a new top end only to have it melt down again you will then see the importance of leak down testing.
kaw rider:
you can build a tester for under $30.00
maddoggy:
--- Quote from: BDI on June 10, 2008, 11:24:43 AM ---This is the spark plug out of the bike I'm working on right now. It's not a very good picture but if you look close you will see the gap is closed. The second picture is of the the piston that almost has a hole clear through it. The cause of this was the fact that the oil injection line came off of the intake and let air in. This caused a lean condition that caused the engine to start detonating. The lean condition made the spark plug so hot the electrode became soft and then the detonation did the mechanical work of closing the gap.
When an engine has a failer you have to treat it like a crime scene. You have to start collecting evidence to find the culprit. Leak down testing is one very helpfull crime fighting tool. If you do not figure out why the engine failed it is very possible you will rebuild the engine only to have it blow up again. When your engine blows up because of a bad main seal and you stick $500.00 into a new top end only to have it melt down again you will then see the importance of leak down testing.
--- End quote ---
well said bdi, once again you are right on the money. chech out the cause thouroughly before you end up wasting a few hundred bucks doing a repair only to have the same thing happen again. MADDOGGY
Hillclimb#42:
Good info BDI. Two thumbs up.
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