81 gs1100e, a top end rebuild story

[CincinnatiKid]

it's time for a rebuild. Not sure what happened, but I will find out here soon.

Took the bike to the track, had a great day, bike was running really great, until I lost a oil cooler hose, the engine oil spilled onto the track, and my engine, and my rear tire, and I went down.
rebuilt the bike, started it up, heard a weird noise on the left side of the engine while trying to get it timed, but it disappeared on it's own. checked behind the alternator cover. nothing amiss.
once the bike was ready to ride for a shakedown, I was hearing a sound that sounded a lot like brake pad/rotor drag, but it was coming from the left side of the engine. kind of like a sliding sound... weird. engine ran fine, but the sound was there and it was RPM dependent.

rode it to work yesterday and got downtown and saw that the crankcase breather was puffing smoke heavily. this happened in winter 2017, I had to put a top end on it then. engine still ran fine, started easily, idled ok without having to adjust any settings from track day. got it home, didn't run it hard.

compression test results tell the tale:
1 -120
2 - 80
3 - 105
4 - 110

got the boroscope out and shot some video from inside the cylinders. i'll post a YouTube video of that in a little while. piston 2 crown has some damage for sure.

for now, i'm looking at parts.
probably an 1134 kit, +2mm pistons (about 6-700)
slotted cams because why not ((about 120)
will check integrity on rocker pads
put new valve springs in last rebuilt (gsxr springs as recommended by the shop)
hopefully valves and seats look okay

[CincinnatiKid]

very curious as to what the mode of failure was, more info will come when the engine is opened up.

after the crash @ the track, my ignition cover was broke, the dyna pickups were broke, and the bolt holding that assembly to the crank was bent pretty bad. I was initially worried that there was crank damage, but a new bolt into the crank spun true and concentric. so I felt better about there being no crank damage. no oil has seeped from the right side crank seal. or anywhere else.

I can't see a way that a pretty mild crash (in the grass... no plastic parts broke) could have caused physical trauma into the piston/cylinder. it does seem like it was pieces of broken ring marks in the top of the cylinder. something was in the combustion chamber. tbd. check video for details.

I thought maybe there was something to the oil spraying all over the front of the engine on the 2&3 cylinders, maybe quenching the heat from them while the piston stayed hot, as hot as it's ever been run (15 minutes into a track session, pulling about 8k or so down the straight). a heat mismatch perhaps caused distortion and problems between cylinder wall and piston??

[rphillips]

Heat mismatch seems not to probable. Did the kill switch kill eng. immediately or did it lay on the side idling for a bit ?

[CincinnatiKid]

Here’s the inspection video. My wife helped me cut it together and she lightened the mood with her sound effects library.

re:running, I think it ran on the ground for a bit, not too long tho…. Less that 20 seconds??

[Grimly]

Might be, as the bike flipped you off it over-revved for high and just long enough to stress a piston or cause a valve / piston interface.

[GregT]

IMO you're going to have to lift the head to see where the debris came from and how much damage it's done

If it was just in one cylinder I'd guess a brass screw has come from somewhere along the inlet tract - but it's in three cylinders...

[CincinnatiKid]

Engine is out and has been brought into the basement for further inspection and disassembly.

i wonder what sort of brass screws could have gone missing?? Air cleaners were intact, carburetors seem complete and functioning regularly. I’m very anxious to break into the top end tonight (hopefully).

[CincinnatiKid]

progress is static since getting the GS engine to the basement. I acquired a proper bike for the track, (2009 zx6r) and have spent the evenings after work changing tires.

i'm at work and since I cant wrench I can ONLINE SHOP!!
I don't want to purchase anything until I get the head removed from the GS motor, but i've sorted out a small shopping/wish list:

piston kit w/head gasket K1133 $700
machining $400
air cleaners 005-121 $66
cam chain BF05MUx120 $90
cam chain tensioner rail TGS1100 $75
valve stem seals 99201 $37
hardened clutch hub nut SHN1150 $35
oil pan gasket EC007 $6

about 1400 total. 1100 for the piston kit and machining, and about 300 for the extra stuff.
these are from the APE parts store

Air cleaners, clutch hub nut, and cam chain tensioner rail are kind of "why not" impulse buys. air cleaners have been on there since I got the bike 8 years ago. clutch hub nut, i've seen people mention as a potential weak point. expensive for a nut, but also kind of "why not". replacing cam chain seems prudent, and might as well refresh the slider also. won't purchase until inspection happens, but maybe some of you have some more insight.

[Rob S.]

i'm at work and since I cant wrench I can ONLINE SHOP!!

My kind of employee!

Air cleaners? Pods?

[dgates1]

Cylinder base gasket and O-rings, valve cover gasket?