Sooty plugs on cylinders 1 and 4

[Anonymous]

Hello out there,
We have been having some great weather here in Denmark lately, so I have been riding my 77' GS 750 more often.
But I have noticed that the plugs on cylinder 1 and 4 (the outer cylinders) are black sooty. According to my Haynes this is an indication of over-rich fuel/air mixture or a malfunctioning ignition system.
I have no problems starting the bike and it runs very nicely. The plugs on cylinder 2 and 3 have that nice brown tan, an indication of a correctly running engine according to Haynes.

Since only the plugs on cylinders 1 and 4 are black sooty I was wondering:

-Could it caused by a bad condenser?
-Could it be a bad ignition coil?

I hope it makes sense,
Cheers...

[cbxchris]

Could be a coil going out. Might get a meter out and check it. Usually if there is larger jets they are on the inside cylinders. At least you are not fouling plugs and its running good so far. One more thing would you suppose you have some hardened valve stem seals and its burning a little oil?

[earlfor]

Re: Sooty plugs on cylinders 1 and 4

Yes, it could be a bad condenser. It could also be the timing is retarded on the 1-4 pointset, or the 1-4 pointset is worn and needs replacing.
The first thing I would check is the gap and timing on the left pointset.

Earl

Hello out there,
We have been having some great weather here in Denmark lately, so I have been riding my 77' GS 750 more often.
But I have noticed that the plugs on cylinder 1 and 4 (the outer cylinders) are black sooty. According to my Haynes this is an indication of over-rich fuel/air mixture or a malfunctioning ignition system.
I have no problems starting the bike and it runs very nicely. The plugs on cylinder 2 and 3 have that nice brown tan, an indication of a correctly running engine according to Haynes.

Since only the plugs on cylinders 1 and 4 are black sooty I was wondering:

-Could it caused by a bad condenser?
-Could it be a bad ignition coil?

I hope it makes sense,
Cheers...

[Anonymous]

Thanks for the quick replies.
And yes, I think it is burning a little oil. Actually I see a hint of oil coming out of the valve cover (right side), and right side cylinder.

Could this be the valve stem seals? To be honest I do not know the last time the bike had a valve check...