Intermitent soark #2 cyl. Any ideas??

[80gs850g]

OK, So I have a 1980 GS850G, has just under 63,000 miles on it. The bike has been running great but recently started to lack power so I have figured out that the #2 cyl. isn't firing, occasionally I can feel the bike pull harder for a moment, so I believe it to fire sometimes, aside from possible loose connections, What else could cause this?? I believe if it was the coil, then two cylinders would be out, correct?


It won't let me edit the title

[Arkaloid]

2 things come to mind right off, bad spark plug cap, or petcock leaking gas into the vacuum line that goes to the #2 carb

[80gs850g]

OK, I will test the plug boot in the morning, do you know if there are resistors in them or should it read 0 ohms? As far as the vacum line, could you elaborate? Thanks

[Arkaloid]

Unscrew the cap from the wire. measure the resistance of it, should be around 5K ohms. if one is bad, get all 4 of them.

The vacum line supplies vacuum to teh petcock to allow fuel to flow to the carbs. sometimes the petcock diaphram starts leaking and allows fuel to be drawn in directly into the vacuum line overwhelming the #2 carb with fuel, flooding it, and fouling the plug out.

[80gs850g]

Thank you very much, I will check both in the morning.

[moto_dan]

Thank you very much, I will check both in the morning.

Just a note. The vacuum line should be bone dry when removed, if not then the diaphram in the petcock is leaking.

[80gs850g]

OK, found good spark to the end of the plug wire, boot measured 31000 ohms, which is in spec of 30-33k ohms. ?Vacum line was dry, so I checked the plug itself, looked ok, had spark outside the cylinder, but I cleaned it anyway, and viola the bike ran great, until I washed, then same symptoms, until it dries and I clean the #2 plug, anyway, I need plug wires, Anyone know where I can get coils cheap, as I understand it, I cannot just replace the wires, correct??

[chef1366]

If you get the concept of how the plug caps screw on the wires you can add new wires the same way with a two sided copper screw.

[bwringer]

You can replace just the wires with a butt connector or the copper screw trick, or if you want to really do it right, order a set of the green Dyna coils and groovy new plug wires in the color of your choice.

Here's a great souce for this stuff cheap:

http://z1enterprises.com

Lots of folks here are very happy with Z1's service and prices.

[bwringer]

Also, if you don't know when the petcock was replaced, or if you suspect it might be original, it would be a good idea to go ahead and replace it. A microscopic hole in the delicate diaphragm could easily let enough gas through to cause the #2 fouling yet still leave the hose dry and show no visual evidence of a problem.

A new petcock is maybe $50 - $60 and will probably last another 20 years. #2 fouling is the textbook symptom of a beginning petcock problem. I'd replace it if I were you.

[chef1366]

Hey Brian, what's a butt connector

[koolaid_kid]

Hey Brian, what's a butt connector

Oh, this one is difficult to resist! [-o< \\/

[koolaid_kid]

This is an example of one:

http://z1enterprises.com/detail.aspx?ID=1890

[chef1366]

Oh man

Oh, this one is difficult to resist! [-o< \\/

[80gs850g]

Thanks for all the help, I will look into a replacement petcock,