Second set of dead spark plugs?

[Jackw]

finally got the 550 running, for a bit anyway. Then plugs 3 and 4 went dead(they were new plugs). Changed those 2 out now I just went to start it and plugs 2, 3, and 4 will not fire. but the one good plug fires on all 4 wires? can it be I just got bad plugs twice? can a coil problem kill a plug? resistance acrossed plug wires was 26 Kohms and 3.8 ohms acrossed the power connector? Any Ideas. I'm just about ready to part her out!!

[Nessism]

Are the plugs oil fouled or carbon? And no, you did not get "bad plugs". The problem is somewhere on your particular bike. What is the condition of your air filter?

[Jackw]

yes plugs do seem to be oil fouled. Air filter is new....

[Nessism]

yes plugs do seem to be oil fouled. Air filter is new....

Oil fouled means you need to do a compression test. You may have bad rings. Don't guess on what could be wrong, measure to determine where possible.

[Jackw]

compression is between 120 -140 on all cylinders. I had it out the other day and it was working awesome. What would cause those plugs not to fire acrossed the gap? they are sparking to the head but not acrossed the gap. Can bad coils or ignitor kill a plug?

[chef1366]

Battery needs charged?

[Jackw]

Battery is charged, it's turning over the way it should be. The one plug that is still firing, fires properly on all spark plug wires. When the first 2 plugs went dead on cylinders 3 & 4 I changed them out, I also changed the spark plug caps at that time. I have good spark from the coils with no plug caps on. Now the plugs in cylinders 2,3 &4 are fried. Bike gets lots of fuel, new air filter installed. Valves were set by a mechanic. but I'm thinking of checking the valve clearances again for good measure. there wasn't much on the plugs just a bit of black on them which wipes right off on my fingers. does this sound like an electrical problem. I know that fuel and air are good! can the coils still be screwed up even though the resistances are in spec?

Thanks to all in advance....

[Jackw]

ok, so the plugs are good, but they were oil fouled. Compression is good, so I guess it's time to check the valves??

[Nessism]

Oil fouled plugs indicate oil is leaking into the combustion chamber. Obvious choices include bad oil control piston rings or leaking valve stem seals. Don't mean to doubt you but it more likely that you have an ignition problem of some sort. Considering how the problem effects all the plugs I'd suspect the ignitor. Not sure though. You really need to understand if the plugs are truly oil fouled. After that you can make an informed plan of action.

[jfrankenbiker]

New plugs CAN be bad. I know because I just had one. New NGK B8ES properly gapped began to misfire after about 2 minutes of running. I thought, "No, I can't be a bad new plug",so I checked everything else electrical first including checking points, cleaning up all the wire connections and ground connections, and swapping out for a known good coil. Nothing worked so I swapped the plug to another cylinder and that cylinder misfired too. Replaced the plug and it runs fine now.

The plug was sooty black but not oil fouled. The primary and secondary resistance of the coils were very similar to what you found.

Go for new plugs. NGK may have let some bad ones slip through QC.

Good luck

[Jackw]

I cleaned up the plugs by brushing them lightly with a wire brush, and now all the plugs have a nice blue spark on every wire. I spoke with a guy who does small engine work up the road from me and he said to check the valves. the valves were set by a mechanic, but if they were not set properly can this let oil into the chamber? The bike was working pretty good before the valves and Carbs were done. I have checked the carbs though and gas is flowing well.
I don't think it's the ignitor, but I guess it could be.
I checked just the plug wire with no cap and get a nice fat blue spark in every wire. I just put brand new NGK plug caps, and again get good spark on all plugs once they are cleaned up. there is definately oil getting into the chamber.

so really right now I guess I need to know the following:

if valves are out of adjustement can this allow oil to get into the chamber?
Can I have compression over 120 and still have enough blow by to fould the plugs?
will leaking valve stem seals let oil run into the chamber while it's sitting? I assume yes...
and if I'm way off on any of this feel free to set me straight.

Thanks for all the help from the experts on this site, without you guys I'd be selling parts on ebay right now...

[Nessism]

so really right now I guess I need to know the following:

if valves are out of adjustement can this allow oil to get into the chamber?
Can I have compression over 120 and still have enough blow by to fould the plugs?
will leaking valve stem seals let oil run into the chamber while it's sitting? I assume yes...
and if I'm way off on any of this feel free to set me straight.

Thanks for all the help from the experts on this site, without you guys I'd be selling parts on ebay right now...

Leaking valve stem seals tend to allow oil to seep down into the combustion chamber when the engine is sitting and during deceleration when vacuum is high. Do you have a lot of blue smoke out the exhaust on a cold start and during deceleration? Is the engine burning a good bit of oil?

[Jackw]

there is some blue smoke on a cold start. And the bike was stalling sometimes when stopping at red lights, but it would start right up again. I never noticed blue smoke on deceleration. Looks like I got some digging to do.

If the compression is over 120 on all cylinders is it possible to still have enough blow by to foul the plugs?
If the valves are out of spec can this allow oil into the chamber? or is it only the seals that will cause this?

[Nessism]

there is some blue smoke on a cold start. And the bike was stalling sometimes when stopping at red lights, but it would start right up again. I never noticed blue smoke on deceleration. Looks like I got some digging to do.

If the compression is over 120 on all cylinders is it possible to still have enough blow by to foul the plugs?
If the valves are out of spec can this allow oil into the chamber? or is it only the seals that will cause this?

120 is not too bad. Your rings are valves are sealing fairly well. Oil control is another matter though. The valve stem seals get hard over time and maybe some of yours are cracked? Not sure. As the engine wears the clearance between the valves and the valve guide increases, more so on engines with rockerarms like yours (you have the 16v engine right?). Extra clearance allows oil to leak down. Oil control rings also can get gummed up, reducing their effectiveness which is unrelated to the compression rings (although they tend to wear together). Not sure this helps any other than spell doom and gloom. Sorry. One trick to try to free up a stuck oil control ring is to put some Marvel Mystery Oil in the cylinder and let it soak for a couple of days. Other than that I have no ideas other than pulling the head/cylinder and measure everything to see what the real problem is.

Good luck.

[jfrankenbiker]

Valves that are out of adjustment will NOT cause oil burn.