K11 Owners Group

[Scott_Anderson]

Ok, so here's what happened today. Coming home from work, got out on the 4-lane and I wanted to wind-er-up.
I stayed in 4th to keep the speed down obviously, don't need any performance awards....
The motor was singing right along easily 6K-7k, I went to back off the throttle, and no reduction. I tried to snap the throttle a couple of times to get it to back off, didn't work right away. I touched the brakes a bit to load it down some, to down-shift, not a good idea........
As soon as I touched the clutch I realized I did an oooops. I let go of it right away, but not before the motor went little-no load speed. I did finally get the throttle to release, but the result was I now had an obvious mis-fire.
It got me home with 3cyl.
I located the cause of the sticking throttle cable and corrected it. A piece of my fuel line insulation became unfastened from the fuel line and was in the perfect position to catch/snag the cruise control linkage. No longer..

Back to the misfire, 1st I connected my carbtune to see if I could tell which cyl I was dealing with, didn't tell me anything. All 4 still showed decent vac, so that was a good sign anyway.
Pulled the plugs, got the 1st 3 out and they still looked like new, pulled the 4th and low and behold there was no gap. Bosch XR5DC
Near as I can tell the top of the piston came up and hit the plug. Got my light out and I couldn't see any damage thru the plug hole, ran a compression test, came back good 185+.
So I re-gapped the plug, put it all back together, and it fired right up as if nothing was wrong. Took it out on the highway again, ran it up to 7K+, no problems. So I'm not sure if it was just a fluke that the piston tapped the plug, or if it's a sign of excess piston travel to be concerned with, or possibly just a layer of carbon buildup on the top of the piston.

Thoughts?

Oh, btw this was the '97 with 49K miles.
_________________
Ride safe.



1995 K1100LT 0302044
1997 R1100RT ZC62149
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.)

[SugarHillCTD]

I can't imagine that a piston would suddenly travel too far. Any play in the big or little conn rod would probably be very destructive very quickly.

If it was carbon buildup then the spark plug gap would be closed up when you pull it again. Maybe do that?

This sounds too stupid to even ask you, but the #4 plug does have the crush washer on it, right?

Maybe your bike needs to have an exorcism.

Let us know if you find any more clues.


I know that every situation is different, depending on what road you are on and the amount of vehicles around you- but as Drake has posted, I think that we all need to remember that in similar circumstances the kill switch is your best friend.
_________________
John & Cathy

'92 K100RS4V Pearl White SOLD
'04 K1200GT
IBA Several-SS1k, BBG, 50CC NYC to S.F.

[Scott_Anderson]

Yes, the plug had the crush washer, I even compared the new one to the old ones I pulled last month, because they were different plugs(both were Bosch though) to compare the thread length and they were the same.

Yea, I hear you about the kill switch, I did have my thumb on it in preparation, but I was able to get the throttle released. I was on an open road, with no traffic, and by myself so I did have space to work with it a bit.
_________________
Ride safe.



1995 K1100LT 0302044
1997 R1100RT ZC62149
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.)

[jpberens1994K1100RS]

Been forever since I've seen or heard it.
But, marginal fuel, like old winter storage fuel, could cause " detonation " which slams the gap shut. I've seen this more on boat motors than cars & bikes.
The conditions you created accidentally, higher than normal revs near or at redline, would have been ideal for pre-ignition/detonation even without load. At those revs it could have detonated 50 or more times before you got it slowed down.

If it's not that it has to be a mecahnical issue. A spun bearing in the crank which for now lodged back into the correct position? It'll run for a while, but if it is a mechanical issue it will chew itself up eventually even if for now the compression is good.
They are tough as hell motors though. Might as well keep riding it and keep an ear open for any signs of deterioration in running conditions.

So sorry that happened to you.
_________________
1993 K1100RS that I'd rather be riding FAST!
2014 Moto Guzzi Norge