bottom end death

[shifty biscuits]

hi. i have been using my gg sm250 for the last couple of years to run the short distance to work, back roads normally. today i forgot what i was doing and got on a straight fast road. ripped down it, no choice really, 4 or 5 minutes pretty much flat out, just hoped for the best. got off the main road, still going fine... quarter mile later its had a lil hesitate or two, then feels like fuels run out n dies, fuel was getting low when i left so i chucked tap on to reserve n thought no more, kicked it to life, 2 mins later rear locks up, clutch in quick time. stop. push home...
now i recently threw in a new piston and had the jug plated, so i feared i'd wrecked that. stripped the top down just now and its not totalled, some marking to the hone but not gouged. looks like its all got a bit hot but it came apart easy. problem is the bottom wont turn with the top end off.
is this a common thing? whats likely damaged? i was not expecting the bottom end to be done, now im scared the crank or casings could be toast

 

[(F5)]

My left main bearing just failed sort of similar. 2007 so due to so not worried.

 

[shifty biscuits]

ah ok. so if the main bearings let go, do they just collapse and thats it or are the likely to damage casings or cranks on the way out?

 

[(F5)]

Only if you ignore the warnings signs and blast on till it stops. Plastic cage could be OK to break up. If right main or worse the big end metal cage or rollers could follow the gas path up the transfers and like jumping out of a falling elevator messiness ensures if you don't get fully out the door in between floors.

 

[shifty biscuits]

thats what im scared of haha. i'll tear it down when i get a free few hours and assess the damage.

 

[CDN Rick]

Your cases will be fine. You either locked up one of the main bearings or locked the big end of the conrod to the crank. Either way you'll have the cases split.
While in there you may as well replace all the bearings and seals on everything. Then you know its good to go for years and years again.

 

[RBrider]

On my 200, the mag side main bearing lost the cage and it bound up between the case & the crank. It gouged the case a little, but a good cleaning & fresh bearings & seals & it was good to go.

RB

 

[shifty biscuits]

yeah i'll get the thing split and refresh the lot. fingers crossed its not damaged any expensive bits