Cylinder 2 not firing- '78 GS1000

[Dweller]

Hi, I'm new here and new to GSs but not to motorcycles. This is a very useful website.

I am looking at a 1978 GS1000 (maybe be a '79 model- manufactured in August of '78). The bike is in surprisingly good shape with 16K showing on the odo. It starts and runs, but cylinder 2 is not firing. An examination of the plugs shows three perfect plugs and number 2 that is wet with fuel. I did a cranking compression test and the two inner cylinders are at about 145-150. The two outer cyclinders are at about 140-145. The motor tries to clean out above 5000 rpm, with the bad cylinder catching for a split second then back to miss.

I think its ignition related, but the other cylinder on that coil is working fine. It could be a plug wire, but the wire itself looks perfect. Is there any common known issue with these bikes that would cause this condition? I'd like to buy this machine, but I'm not sure about parts availability, etc.

Thanks for any help!

[Dweller]

Oh, forgot to mention that I switched plugs with no change. Its not plug related...

[7981GS]

Perhaps this might help...

http://www.z1enterprises.com/NGK-Resistor-Spark-Plug-Cap-12mm--10mm--120-degree-elbow---VD05F-425.aspx

Eric

[tom203]

When you say #2, do you mean second from left as you sit on bike?

[Killer2600]

Have you checked for spark on #2 and compared it with at least one other good cylinder? I'd do that because while wet plugs typically indicate good fuel, a flooding cylinder/engine will not be able to fire - just too much fuel.

[Dweller]

When you say #2, do you mean second from left as you sit on bike?

Yes, that's correct.

[7981GS]

Perhaps this might help...

http://www.z1enterprises.com/NGK-Resistor-Spark-Plug-Cap-12mm--10mm--120-degree-elbow---VD05F-425.aspx

Eric

Did you miss this somehow???

[Dweller]

Have you checked for spark on #2 and compared it with at least one other good cylinder? I'd do that because while wet plugs typically indicate good fuel, a flooding cylinder/engine will not be able to fire - just too much fuel.

With the bike running, I wiggled #2 plug boot/wire and was getting an intermittent shock to my fingers. But it did not seem consistent.

I'm pretty confident that the engine is mechanically sound, so I'm still leaning towards buying it. The miss will be another bargaining tool I guess...

[Dweller]

Did you miss this somehow???

No, I didn't miss it. Thank you for the link!

[7981GS]

Have you tried switching those two coil wires to see if you get the same result in the other cylinder?
Could be the coil wire also but a lot of people on this forum have found the boot to be the problem.

Eric