82 gs1100gl 1 cylinder colder than the rest

[Greg7]

I have an 82 gs1100gl
Was messing around with an infrared thermometer the other day and shot all the exhaust temps right where it bolts to the cylinder out of curiosity.

Noticed the right outside cylinder was 197°f while the other 3 cylinders were in the 400°f range.

Haven't noticed any running issues and it starts right up every time. So I'm assuming it's been like this for the 2 years I've had the bike??

I know the cylinder is firing because when I pulled the plug wire for the cold cylinder and started the bike it idled poorly. Would it run colder if it was running way too rich maybe?

Plan on doing a compression test hopefully tomorrow. And I guess it would be a good idea to have the carbs synced. Besides that what should i look for?
Thanks

[Rich82GS750TZ]

Before syncing carbs, are your valve clearances in spec?

[Greg7]

IMG_20200625_230356623.jpg
Here's the plug. Definitely getting fuel and running rich.

[Greg7]

Before syncing carbs, are your valve clearances in spec?

Haven't checked yet. I'll do that too. It's been on the list

[Rich82GS750TZ]

That plug looks rich but also wet. Maybe check the gap?

[rphillips]

That plug isn't firing, that's why it's so wet. running rich would be black, maybe even soot build-up, but not wet. Just my opinion.

[Greg7]

That plug looks rich but also wet. Maybe check the gap?

Will do. Do you happen to know what the spec is? I'll do some looking around to see if I can find it in the meantime.

Edit: .28-.32 is what I've found listed

[rphillips]

Don't clean, gap, nor change anything about the plugs, just swap your #4 plug to #1 cyl. & the #1 plug to #4 cyl. If #4 gets hot, as the others do, your plug is the problem, if #4 is still cooler than the others, you'll know the plug is not the problem.

[Rich82GS750TZ]

Yes, what rphillips said. Do the logical things that don’t cost any $ first to rule out a bad plug. And no, I don’t know what your plug gaps should be. Should be in your owner’s or shop manual, or both.

[Greg7]

Ended up being a bad gap on the plug. Was at .2 so I gapped it to .30. Went for a ride, ran better than ever before and temp is within 20° of the others.

[Rich82GS750TZ]

Pull that plug and see if it’s still wet. I’m curious.

[Nessism]

Haven't checked yet. I'll do that too. It's been on the list

Failing to keep the valves properly adjusted will lead to engine damage. You might want to read the Newbie Mistakes thread linked in my and Rich's signature before it's too late.

[Greg7]

Pull that plug and see if it’s still wet. I’m curious.

Just pulled plug after riding. It's no longer wet.

[Rich82GS750TZ]

.................
Glad that fixed it, BUT. Isn’t there always a BUT? If you have not personally had the valve cover off and at least inspected and measured your valve clearance, and know that the gaps are in speck, DO IT!

[Greg7]

Will be doing that probably this weekend. Need to order the valve cover gasket in case it gets wrecked during removal. Was going to have my buddy do it but he said he's basically too intimidated by bucket over shim valves.