weirdest bearing failure I've EVER seen, and a few questions

[bobthebiker]

I'm kinda new to the katana world, but not at ALL new to fixing motorcycles, after building my last bike literally from the ground up.

Anyhow, I'm working on my friend's 93 Katana 600, which has an earlier head I think, one of the ones with a screw and locknut adjuster rather than shim and bucket valves like the diagrams I've seen show his bike having.

one of those adjuster screws somehow came OUT and fell into his oil pan, which combined with a rod bearing rattle when running prompted him to remove the motor and bring it all to me.

upon disassembly, I took 3 of 4 rods off the crank, and all looks absolutely great, until I did the #3 rod. as soon as the end cap came off, the bearing shell literally FELL OUT of the cap leaving me asking with a little profanity WHAT THE? somehow the bearing shell distorted shape, and actually curved INWARDS. what causes that? the only two things I can think of is lack of lubrication and high rpm, but I would imagine that insufficient lubrication would also affect all the bearings, not just the #3.

can anyone shed a little light on this for me please?

[Kreylyn]

I'm kinda new to the katana world, but not at ALL new to fixing motorcycles, after building my last bike literally from the ground up.

Anyhow, I'm working on my friend's 93 Katana 600, which has an earlier head I think, one of the ones with a screw and locknut adjuster rather than shim and bucket valves like the diagrams I've seen show his bike having.

one of those adjuster screws somehow came OUT and fell into his oil pan, which combined with a rod bearing rattle when running prompted him to remove the motor and bring it all to me.

upon disassembly, I took 3 of 4 rods off the crank, and all looks absolutely great, until I did the #3 rod. as soon as the end cap came off, the bearing shell literally FELL OUT of the cap leaving me asking with a little profanity WHAT THE? somehow the bearing shell distorted shape, and actually curved INWARDS. what causes that? the only two things I can think of is lack of lubrication and high rpm, but I would imagine that insufficient lubrication would also affect all the bearings, not just the #3.

can anyone shed a little light on this for me please?

I believe the Kat and early GSXR motors had issues with oil being supplied to #3 and #4 when the front end was very verticle while running.

In other words... they don't oil well when running wheelies.

Don't know if that was the issue or not, but that could be one possible issue.

Krey

[bobthebiker]

hmmm, as far as I know the front wheel has always stayed planted on pavement, although the owner favors HARD acceleration in every gear, like full throttle with no warmup even in mornings. in my mechanical experience its generally very abusive behavior on his own bike, but thats just my feelings towards it.

[waffenampt]

cold thick black oil doesnt flow the best on a cold start -even when red lining it

[Thomas Dylan]

the only two things I can think of is lack of lubrication and high rpm, but I would imagine that insufficient lubrication would also affect all the bearings, not just the #3.

You didn't expect all four bearings to fail at the same time did you? Something has to fail first. Maybe #3 was leaner than the rest, or not enough bearing clearance ....

[Trackerrrr]

Could be a defective bearing also from the factory.

[waffenampt]

Might wanna check the oil passages in the crank for sludge or other contaminants? Id also be checking the oil passages that lead up into the cracnk

[bobthebiker]

not a bad idea at all, since the whole motor is apart in my engine medical bay, I may as well.