*DUW* my GS engine finally opened up..

[starshooter10]

so... jan 3rd? i took my motorcycle to a free dyno day...

yeah i know why dyno a 500 blah... why not?

long story short i was beating the shaZam! out of it dyno's supposedly are super hard on the vehicle... and i MAY have POSSIBLE been low on oil :look:

anyway...

i finally got around to figuring exactly what went wrong... tooke off head and here's what i found:









































Im thinking i might rebuild it but im still unsure about how much damage has happened...

outside of the obvious pistion welded to the sleeve it looks like the rest of the piston held onto the connectiing rod and ended up smacking into the couterweights...

it also looks like it may have hit the bottom of the engine case.

if i do rebuild this engine im 95% sure im gonna bore it out and make it a 541? (vs the stock 487)

also cruising in first always made a funny sound maybe i'll check it out while it's out the bike and taken apart...

any thoughts?

~Vince

[starshooter10]

*update*

after i started to remove the shattered chucks that where my piston and sleeve...

the piston is pretty well jammed into the sleeve (though it DOES move with a bit of force)

i looks like he connecting rod is the culprit (maybe the piston seized then the connecting rod broke)

anyway the connectiong rod is laying on top of the crank... and i still cant find the bottom end of it

+_O

[starshooter10]

hehe you should see the connecting rod i pulled out the the engine :



now im waiting for buddah to say it's an easy fix and he'll send me the parts for 28$ =-P

[starshooter10]

there is some light scoring on the cly sleeves but mor the most part the look okay >_<

the piston that WAS stuck came out NP.... after i tapped it with a hammer to get it to seat right.. it was binding in there... just a little cockeyed

i'll drain what oil was left and flip it over tomarrow

[shiznizbiz]

wow! Thats rather awesome.

[starshooter10]

wow! Thats rather awesome.

yeah i though it was simply awesome...

sad but awesome (its okay though i just ride my roomates GS now.. haha)

still cant figure out what went wrong in the first place though...

i see my piston exploded... my connecting rod is bent BAD and it hit the crank case pretty good

BUT the remains of the piston came out easly and the whole assembly still movves... (though stiff) it moves...

so it didnt SEIZE

i though it seized but really it was the counterwheights smashing againts the wrist pin



\the only thing i can think of ATM is that the cap for the connecting rod (forget the name ATM) had a bolt walk out...

but if that where the case you'd think my valves would be f%&ked... yet they are fine (have alot of buioldup but are not fdamaged

[ohgood]

can't quite put my finger on it, but something doesn't look right...

maybe you just need to change your plugs and call it a day ?

no really, if you were dyno-ing the bike, and this happened, i think it's another good example of why dyno-ing a gs is a bad thing.

dyno's don't have to be hard on a vehicle/bike. i mean, if you don't flog the crap out of it, just ride it like normal, you'll get close to real-world numbers, instead of those -i-never-ever-ride-in-thrid-gear-at-9500-rpms- kind of numbers. there really isn't a need to judge any engine at redline anyway. not like you use that power (hopefully) while riding.

seems like dyno's SHOULD be checking the off idle power, and the torque curve from idle to 75% of redline. making the portion of the torque / power from off idle to %75 would make ridability sooo much better for commuting, playing, joy rides, etc.

2 cents- hope your new engine doesn't get flogged as badly

[sledge]

Thats not happened instantly, see the discolouration around the big-end cap and the state of the bearing shell? The bearing has overheated, the rod has seized onto the crank and its thrown the piston against the cylinder wall instead of pulling it down/pushing it up.
It must have been rattling its knackers off before it went.

[5thAve]

Sad but awesome, indeed! 

Sledge makes an interesting diagnosis.  I wonder how much other damage you're going to find in the bottom end.  If rebuilding, you definitely need to pull it all apart and measure tolerances on all surfaces, inspect for damage, etc. That's lots of work.  You may be better off just buying another motor (and boring it out, if you wish).

[gearman]

A catastrophic failure like that puts tremendous stress on the crankcase. I'm with 5thAve...replace the engine.

[The Buddha]

The distance between rattling or clicking and dead is ~10 miles or so at 60 mph. I've seen 2 motors fail and mostly its that distance give or take.
I'd toss it and get a motor, not futz with it.
Cool.
Buddha.

[malcman]

Nice Carnage 

[bill14224]

I agree with sledge for the second time this weekend.  A rod bearing failed and took out the rod and piston.  If the piston failed the rod would probably still be intact as it is much stronger than the piston.  I also agree with Buddha.  The cost of new parts to rebuild it is prohibitive.  It's much cheaper and easier to replace the mill.  You can also sell the heads and any other good parts from the old engine.

[GeeP]

Thats not happened instantly, see the discolouration around the big-end cap and the state of the bearing shell? The bearing has overheated, the rod has seized onto the crank and its thrown the piston against the cylinder wall instead of pulling it down/pushing it up.
It must have been rattling its knackers off before it went.

Yes.

First thing I noticed when I saw that photo.

[starshooter10]

well it certainly wanst 10 miles from vroom to clunk..

more like 100yards

though that does seem like the most probally cause of failure..

the rod seized started to bend pushed the piston sideways that sent it cockeyed... that made the piston bind then on the down ward motion it just ripped the bottom of the piston off

[oracleofmist]

I agree that the Dyno is a bad idea. I believe it is a bad idea for any air cooled bikes. At those speeds they depend on natural airflow of the bike moving to cool it down. Putting that kind of stress on it without cooling will heat stuff up way too hot. Anyhow I was down the far when I redid the exhaust valves and piston rings. It probably would have been find minus the dyno.

[sledge]

BTW.........Scrap the rear tyre too.

[starshooter10]

BTW.........Scrap the rear tyre too.

[beRto]

Wow, that's brutal

Thanks for sharing the detailed pictures. 

[Kurlon]

I agree that the Dyno is a bad idea. I believe it is a bad idea for any air cooled bikes. At those speeds they depend on natural airflow of the bike moving to cool it down. Putting that kind of stress on it without cooling will heat stuff up way too hot. Anyhow I was down the far when I redid the exhaust valves and piston rings. It probably would have been find minus the dyno.

Dynos aren't a problem as long as you pay attention to what you're doing.  A proper dyno room will be setup with at least two fans to provide directed airflow to the front of the bike, along with big air circulation for the room itself.  Pay attention to the temps while working, etc.  My GS has spent some time on the dyno with no ill effects, I've got over 100 runs logged on one of my air cooled single pitbikes.  The only time I've had trouble is when I jetted too lean not realizing how much of an impact a friend's port job was going to have... melted a hole in that piston in one pull.