GS650 Electrical/Cylinders/Spark Plugs

[Gadus]

Hi, folks. I am a new GS650 rider (I'm new, the bike is an '83 GS650G). I bought my bike this past summer for highway commuting and have noticed some minor "issues".

ISSUE 1:
It appears the bike has an appetite for spark plugs, at least in one cylinder. The right side (when seated on the bike) inside cylinder does not fire, even with a new plug. Even when switching both right side plug wires, the same cylinder does not fire.

ISSUE 2:
When the bike is running and you touch the spark plug wires on the right side, you feel voltage through your hand.

ISSUE 3:
If I am idling for a long period of time (i.e., slow traffic), the battery eventually wears itself down and the bike dies. This is more fun when it happens while stuck in the aforementioned slow traffic.

I am mainly worried that the more I drive on three cylinders, the more damage I am doing to the engine. As well, reading that this era of GS models have a history of wiring troubles, I worry something might fry (hopefully not me).

These may or may not be related issues, but I do not have the knowledge to ascertain such. Any help from those more experienced would be much appreciated. I hope I am providing enough information.

Thanks for "listening."

[trippivot]

your test of switching plug wires will not produce the results you are looking for. the combustion cycle are 180 degrees out . so you are trying to fire during overlap not compression.
plug cap or tight valve or carb trouble 1 of those 3 on #3


do a visual spark check.. plug in the cap grounded to the engine on all 4 cylinders spark should be blue on all 4 while hitting the starter button.

good or bad???

next is a general compression test- use your finger or thumb over spark plug hole while hitting the starter button. not too concerned with how high the pressure is just want to feel a mild~strong push of air when turning over all 4 should be similar if there is a dead hole you are looking for that on your problem cylinder.

if those tests are good and similar on all 4 then by process of elimination you have a fuel problem

[hikermikem]

First basic check would be to make sure the plug wires from the coil are all on the correct plugs/cylinders...

When sitting on the bike, the cylinders from left to right are numbered 1, 2, 3, 4.

The plug wires from the coil on the left side (under the gas tank) should go to plugs 1 & 4.

The plug wires from the coil on the right side (under the gas tank) should go to plugs 2 & 3.

[Gadus]

Roger that, hikermikem. Checked, and they are correct.

[maro]

make sure your plug caps are not cracked, in fact for good measure, replace them with new ones.

Is the bike not running on all 4 at all times or just when you are off idle. Feel your pipes after riding a bit. Does the bad cyclinder pipe get warm at all. It might be a idle circuit issue in the carb. Might be good to get the carbs cleaned over the winter if you haven't yet.

[Gadus]

The ends of the spark plug cables (caps?) are cracked, especially the one with the "dead" cylinder. Now, all four spark plugs are in working order; actually, the "dead" cylinder in question does work from time to time (I tested this by systematically pulling off each spark plug cable one at a time to see if it made a difference, and cables 1, 2, and 4 always did and cable 3 sometimes did). This leads me to believe that it may be a problem with the cable cap... which should be cheap to address. Might also explain why you feel a bit of current when you touch cables 3 and 4 (voltage leak). I'll test out some new caps... my bike is now put away offsite for the winter but will try some weekend soon to work on it and post my results (or follow-up questions).

[skidMarkNZ]

spark plug cap on the cylinder that is not firing is stuffed....

just buy a cap only only be a few bucks, problem solved, it will have a crack and be arcing against the head.

[skidMarkNZ]

The ends of the spark plug cables (caps?) are cracked, especially the one with the "dead" cylinder. Now, all four spark plugs are in working order; actually, the "dead" cylinder in question does work from time to time (I tested this by systematically pulling off each spark plug cable one at a time to see if it made a difference, and cables 1, 2, and 4 always did and cable 3 sometimes did). This leads me to believe that it may be a problem with the cable cap... which should be cheap to address. Might also explain why you feel a bit of current when you touch cables 3 and 4 (voltage leak). I'll test out some new caps... my bike is now put away offsite for the winter but will try some weekend soon to work on it and post my results (or follow-up questions).

Yeah that confirms it, replace the caps man...

and for gods sake stop electricuting yourself, thats 30,000-40,000 volts mate! just low amps but still no good for ya!