Howdy,
I've changed my spark plugs last month after it the rear cylinder plug went bad. Now it seems the rear plug has gone bad again. Can anyone give me symptoms/causes of what could be causing this? Any help will be greatly appreciated.

Thanks

 

Are the plugs wet with either gas or oil?

 

Post a picture of the two plugs.

 

Thanks Filthy and Steve for your responses. Sorry I didn't get back to answer sooner as I was driving up from L.A. to San Fran and submitted this b4 I left.
I've attached a jpeg of the plugs. The plug on the left is the rear cylinder and the plug on the right is front. The front (right plug) is a little oily and the rear (left) dry but a little fouled.
Hope this helps you help me.

Thanks again

 

They look fuel fouled. What carb are you running. Answer the following questions for us and we will probably be able to help.......

What carb are you running.
Have you recently done any jetting work on it?
Is your bike starting easy and running good.
Is your battery/ignition in good shape.

 

Thanks Al,
I'm running a S&S Super E and have been for many years.
No recent jetting work.
It starts easily but sounds a sputters when idling. It was running good b4 this issue.
New battery and ignition is good.

 

Try a set of Bosch platinums # 4219 you'll never look back !

 

What type of ignition and what is the gap on the plugs you are running? For the points the gap should be .028 to .033 for electronic .038 to .043.

 

I really appreciate all the help on this. Thanks George and Filthy. I try those plugs mentioned. I'm running an electronic ignition. Would a blown head gasket be also a possible culprit and would what other signs should i look for?

 

Does the bike blow white smoke? Do you have oil in the exhaust ports? If yes you could pull the headbolt closest to the exhaust on the left side. If it is oily you have a problem with the gaskets.