After almost five months after my engine died due to lack of oil - http://gstwins.com/gsboard/index.php?topic=40479.0 - I split my cases to actually see what went wrong where. The final speculation was that I had spun a bearing thats what caused the rattling noise. However, I am not sure if this is the case. As far as my knowledge goes, I did not find any bearing broken and they were rotating properly, so is it really a spun bearing? Which part should I be checking for spun bearing exactly? If its not the spun bearing, could it be the worn out cam guides in Image.L causing the rattle?

A.

B.

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L.

the bearing bores look like they got hot/burnished, but that may be normal for motorbike engines, no idea.

the cam bores really look like hell though. you can see galling on the bore. ouch.

(i've never split a case, just going by experience, to be disproven in 3,2,...)

It looks like the rod bearings may have gone bad... notice the discoloration on the crank at the rod. The rods normally have a similar discoloration from oil starvation as well.
Rod bearings normally fail first.

Quote from: dgyver on September 07, 2008, 04:34:58 AM
It looks like the rod bearings may have gone bad... notice the discoloration on the crank at the rod. The rods normally have a similar discoloration from oil starvation as well.
Rod bearings normally fail first.

+1
That looks like an engine thats been seriously starved of oil and probably not worth rebuilding if you can get a reasonably priced 2nd hand one. The cam bearings look bad, main bearings not good, rod big ends will be very bad going by the discolouration as dgyver noted. Bad luck.

ok new to these motors so i have to ask

WTF is the cam looking thing in the bottom of pic B below the crank? is it some sort of balancer that spines with the crank

sorry i don't have anything productive for you

Quote from: Mdow on September 07, 2008, 06:29:54 AM
ok new to these motors so i have to ask

WTF is the cam looking thing in the bottom of pic B below the crank? is it some sort of balancer that spines with the crank

Correct....go straight to the top of the class 

Pull this cap off and see what you find........it wont be pretty.

Sledge is on the nose ... the black rod bearing cap = bad news. I have one that is like that ...
However you have galled cam bearings too ... mine was sorta marginal ... bit not too bad.
The damn 04+, can starve of oil even when there is plenty ... the oil pumps into the oil cooler and down into the sump. I may modify it with a check valve and run it on my older motor ... Oil pressure ... not just oil is needed. The good thing is that the pan has all the requirements for an oil cooler ... its an easy swap into a 89-02, 10 minute swap literally ... but without a regulator you will lose oil pressure ... but gain a cooler motor no doubt. An inline regulator (which also I have ... just need to find it) will do the trick.
Cool.
Buddha.

  Right on... one of the connecting rod has a huge play. Thats what must have been causing the rattle sound. This is the one that is discolored. Removed the rods to see the bearings almost worn out. Feels nice to see what actually went wrong. Can this engine be still rebuild?

Mole, I actually did buy a used engine long back and my bike has been running great

Quote from: sledge on September 07, 2008, 07:06:22 AM
Pull this cap off and see what you find........it wont be pretty.

i would have a shop check that crank and i would replace that rod just cause all that heat scaring you can see.

if the piston walls are not in bad shape i think it could be put back together

o ya clean that head up were the cams were

No problem to rebuild. The scoring on the cams journels would need to be checked, tough to tell how deep by pics.
My 97 motor had the same failure when I bought it. I replaced it with a GS450 crank and rods.

Quote from: The Buddha on September 07, 2008, 07:43:22 AM
Sledge is on the nose

Dont give me the kudos, I just elaborated on DGs comment.

I have a similar motor and the crank has a flat spot under the rod journal. Its gonna cost ya plenty and remember some of this stuff has a memory. Any over heating experience will come back to bite you. The crank may be turned or built back up and then turned or something, and the heat actually affects it very little, cos they are heat treated to begin with, maybe weld it and need to stress relieve it. I dunno, I am not putting mine back together ... I'll fix upper end problems - broken valves, leaky head gaskets etc, but I aint doing crank ...
Cool.
Buddha.

yeah buddha, crank is bad, and illegal too 

sounds like too much work for too little benefit..

thanks yall for helping me out to put an end to a long stretched story.