K11 Owners Group

[N41EF]

So, just because I didn't know when they were last replaced I decided to replace the spark plugs. The first three were a nice tan color, not build up, then when I got to number 4 I pulled it out and it was black and gooey. You can see a buildup on the insulator that looks oily.



It ran good, but had a miss at idle sometimes. Before I pulled the plugs I had done a 20 mile interstate blast at 75mph, then three miles through town to get home.

It didn't smell like gas, so I don't think an injector is leaking. I used the center stand always, so shouldn't be pooling.

I installed NGK plugs with the single electrode and seems to run really well right now.

Any ideas where to look next?

[Scott_Anderson]

How many miles on the bike.

Any idea the last time the valve clearances were checked?

You could use some injector cleaner in the gas. It's possible you could have an injector that's leaking a little bit. Cleaner can't hurt and it most definitely could help.
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Ride safe.



1995 K1100LT 0302044
2017 FLHTK Ultra Limited
Garmin StreetPilot 2820
Garmin Zumo 550
Garmin Zumo XT
"One who does not ask questions is ashamed to learn" Danish proverb
1997 K1100LT 0302488(R.I.P.)
1997 R1100RT ZC62149(sold)

[N41EF]

14200 miles. Don't know if the valves have ever been checked. I had the same though on injectors so I just dumped a botle of chevron techron cleaner in the tank.

I've put about 500 miles on it in the last month, it had set a lot off and on for several years.

[Number 6]

You should also check throttle sync.
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I am not a number, I am a free man.

94 K1100LT

[exavid]

It wouldn't hurt to do a compression check and see how that cylinder compares to the other three. It could be a valve not fully closing due to a sticky guide, piece of carbon or burnt and warped. Checking valve clearances will show up a non-seating valve as well but a compression check is quick and easy and will give a good indication of a valve or ring problem.
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Paul W.
2013 C650GT
1995 K1100LT

Molon Labe

[Shane]

I just had that problem. Compression and leak down was all good. Found out the big round boot on the throttle body was cracked and worn through causing the computer to dump more fuel in the 4 cyl. I ended up having the fuel injection rebuilt and cleaned because it was so dirty. Now the response is amazing! I have only put about a thousand miles on since the work last week and haven't checked the plug yet.

[Dieselyoda]

[552255]

I would check for vacuum leaks in the entire throttle body 'stack'...the rubber boots, bushings, gaskets, hoses all develop cracks. If those are original T.Body bushings with 142k, you can bet they have cracks/leaks. Same goes for all your rubber hoses etc. With that many miles, replacing the rubber bits is most likely needed. You can also replace fuel injectors (ebay 4-hole type) for 100 bucks...and spark plug wires from magnecor are available.
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1997 K1100LT-SE
1996 K1100RS-SE
"Black & Silver Duo"
Lincoln, NE

[N41EF]

Bike is just now to 15k miles, not 142k. I pulled 3 and 4 this weekend and they were nice and tan. The bike had set off and on for several years when I bought it, and I ran a huge dose of fuel injector cleaner through it. I'll check them again when I do the 16k service in a month or so.
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2014 R1200RT Water Cooled
2001 R1100S Light
1993 K1100LT. Nissan Ice Blue.(Gone)

[Dieselyoda]

There is a rule of thumb, back when I started my career in the '70's: Gasoline engine problem, change the plugs.

It's the simplest, cheapest, may solve a problem, or not.

Always gives me a good start to know if the problem requires more time/effort which = $$$