So You Really can Break a Brick !!

This BB has been way too quite lately, ... so I thought I would share this

Yesterday afternoon, leaving work, I pull out of my parking spot and make a 90 deg left. I'm still going at a walking pace in first gear as I straighten out and begin to accelerate a bit when my 1988 K75S (135K miles) stops INSTANTLY with a total driveline lockup. If I had been going at road speed, I probably would have been pitched over the front end or highsided off.

There were no unusual sounds before or after and no noticeable vibration. Once I figured out that ,no, I had not done something dumb and ,yes, the bike broke something I did a little diagnosing. I can get the transmission into neutral (not sure if it is a false or real neutral) and the real wheel will roll without making and unusual noises. With the transmission in neutral the starter will not turn over the engine at all. I'm a bit surprised I did not melt the starter relay. Pulling in the clutch lever allows the starter to spin normally and the engine fires like normal. Slowly letting out the clutch brings the engine to a halt.

I'm guessing the hard parts in the engine are OK because the engine runs with the clutch disengaged. The output side of the transmission, drive shaft and FD are probably OK because the rear will roll. That kinda leaves the input side of the transmission. Maybe something broke and jammed the gear train. Maybe the tranny is in both first and second preventing any gear train rotation. Anyone care to offer a prediction what I will find if I open the tranny ?

All in all, it could have been a whole lot worse instead of just an inconvenience.

Holy F...!!!

That's kind of my worst nightmare, especially not hearing any noise or feeling any vibrations beforehand that could make you prevent this. :?

as you diagnosed, engine is OK, output side of tranny OK but something came loose on the input side.....you can't break a K!!! Open and have a look and ALL of us would like to know what you find because "instant lockup" especially on a freeway is the stuff nightmares are made of. Good luck, OoB

With the transmission in neutral, letting out the clutch gradually slowly slows the engine RPM until the engine stalls.

With the bike on its centerstand, I put the transmission into fifth gear and tried to rotate the rear wheel by hand. The drive train is locked solid.

[quote="cldmcnslim"]This BB has been way too quite lately, ... so I thought I would share this

There were no unusual sounds before or after and no noticeable vibration. Once I figured out that ,no, I had not done something dumb and ,yes, the bike broke something I did a little diagnosing.

Something must have come loose and jammed the gears.

I can get the transmission into neutral (not sure if it is a false or real neutral) and the real wheel will roll without making and unusual noises. With the transmission in neutral the starter will not turn over the engine at all.

Must be a false neutral; that's why starter only works with clutch lever pulled in.

I'm a bit surprised I did not melt the starter relay. Pulling in the clutch lever allows the starter to spin normally and the engine fires like normal. Slowly letting out the clutch brings the engine to a halt.

As the clutch begins engaging, it comes up against that immovable part of the input part of the gearbox and stalls the engine.

My guess is that you broke a finger on one of the selector forks.

You have no other option but to open up and tell us what you find. Waiting with bated breath! Ciao, OoB