Fouled Plugs In 30 Minutes Or Your Money Back

The sitch:

I ride with brandy new plugs (gapped, torqued, etc.) for 30 minutes and by the end of it, they are COMPLETELY carbon-fouled. To the point where if I ride it much longer, one of them gives out (stops firing) and it runs on one cylinder until the other is sufficiently fouled. Then I can wait for a bit and probably get it kick-started up enough to ride for another quarter to half mile but that's about it.

The question:

Can overly advanced/retarded timing cause this? Why so quick!? I'm using the right plugs. Even tried a step or two hotter but no change. WTF?!? The bike would be fairly reliable if it weren't for this.

I've put all my time into the bike and neglected the car. Now I need the bike while the car's in the shop.

help!
-sf

Btw, just bought new points, so that'll be good in any case. (What should I do about the lubricator felt piece that's totally dirty and worn?) In any case, I'll be checking the timing soon but I wanna know if there's something else I should be checking into for those plugs.

Carbon fouling, especially in that short of a time frame, would lead me to believe it's running way to rich.
It could be like you suspect in that the timing is off. Bad plug wires, plug caps, or simply a worn out coil failing once it heats up could also be causing the problem.

Switching to a hotter plug to "fix" this is like putting a band-aid on a gapping wound IMHO.
You are mearly addressing the effect and not the cause by doing this, and can actually create worse problems - burnt pistons/rings/valves, scored cylinders, etc. Granted those are worst case scenarios, but why chance it?

Try the simple stuff first:
Replace the points like you already plan on doing.
Check and adjust the timing.
Check the plug wires, caps and coils - first when cold, and then when it starts fouling out.

I know there are other things/areas to check, but my brain's fading a little bit here at 2:12 in the morn'. :huh:
Heck, I'm not sure I even remember my full name right now! :ohmy: :lol:

My first question is ..this.. is the fouling dirty and dry or wet looking? is it a fluffy black or a brown color? makes a diff about whats possably going on, in there.:huh:

Plug caps ??
condition of plug wires??
voltage at ignition coil??
timing at proper "F" marks??

points cause many problems if set slightly wrong, worn
or if the condensers are out of spec.

carburation is a completly related but seperate subject

Post edited by: trippivot, at: 2006/08/13 09:56

Stupid question: How do you check the wires/caps/coils?? :blink:

The idle is slightly unstable too, leading to the engine cutting out once in a great while during idle, worse when cold.

The plugs are dirty/dry/black/completely covered.

Definitely going to play around with my mixture. The tuning stuff is really interesting...... BUT I WANNA RIDE! :pinch:


RetroRiceRocketRider wrote:
Check the plug wires, caps and coils - first when cold, and then when it starts fouling out.

I have the same problem. Everything was checked and rechecked. I had the compression checed and found all the cylinders to be around 110 psi. Check your compression and see where your at.

To check the caps/wires/coils you need an ohm meter (multimeter). Measure the resistance of the caps (no more than 5k-6k ohms), between each pair of coil wires (no more than 23k ohms) and between the two small terminals of the coil (no more than 5 ohms, should be 3-4 ohms).

steell, great info! i appreciate it. got a lot of fine tuning to do. can't wait to hear that thing hum!!

Actually, carbon fouled plugs are the result of incomplete combustion. Incomplete combustion can be caused by MANY things; especially on an older bike. If you purchase a factory service manual or Clymers for your bike and follow the tune up steps suggested, this will eliminate about 95 percent of the things that can potentially cause fouling. The remain item would be low coil power. See my web site and read the coil repowering article. In general the following can cause severe plug fouling:

1. low compression (rings/valves)
2. valves with no clearance
3. timing incorrect
4. bad plugs, points, condensors, plug caps, plug wires
5. poor spark due to low voltage at coils
6. poor spark due to coil impedence getting real high with age
7. filthy, clogged air filter
8. very high float levels in carburetors
9. very mis-tuned idle circuits in carburetors
10. poorly selected jetting

Get that manual and do a full tune up and also include tightening your cam chain and I suggest there is a good possibility that the problem will disappear. Also, have a look at that coil repowering article.

WiredGeorge to the rescue Yet Again! Good post and complete as usual. Funny you mention the cam chain...

I'm feeling a vibration that reminds me of a rattle from a loose chain but only every once in a while while I'm riding. If I'm not mistaken, the vibration/rattle which is subtle, is accompanied by a "pulling back" feeling in general on the bike. My theory has been the cam chain but I haven't had a chance to go through the process of tuning/tightening it yet.

How exactly is that related? If my theory that that sound/feeling is the cam chain is correct, would the valves be mis-opening (for lack of a better term) or out of sync? Could this possibly cause my slightly unstable idle and some back-firing on coast? Hrmmmmmmmmm.

Thanks again for all the help guys!

The cam chain maintenance is often neglected and probably doesn't contribute but could possibly. If the chain is pretty stretched, the valve timing could be off to the point where the valves are open after they should be relative to the ignition timing (spark occurs when valve is still hanging open a bit).