Big end bearings lucky to catch this one

[pad]

http://members.optusnet.com.au/p-d/PICT0004.JPG

This is out of a motor with 35000 kilometres on it
18000 of witch are from the previous owner over a period of five years.

On my last ride I noticed an increase in vibration from the engine.
I ended up removing the side cover and having a look at the oil Filter mesh, there I found a couple of small flakes of white metal.

The crank looks fine , ill measure up the crank and rod end to see What sort of clearances are there.

The bearing looks like it is suffering from metal fatigue, with the white metal Starting to flake off the back shell

[Steve TLS]

Lucky catch.

I wonder if that's the cause of the vibes though

[zippytlsr]

I'm with Steve there.. wow... really nice catch. any pictures of the crank?

[Sam]

Very Lucky Catch

The pitting is from the excess clearance of the shell. The rod will have started to hammer causing the vibration and failure of the bearing material.

[JarkkoT]

Nice catch, that really shows how the damage starts, so it's a rare picture. usually pics are taken after the damage is total.

is the damage only to lower shell? It's amazing that many times the damage actuall is to the lower shell and not the upper, even thou upper should get more damage, because piston forces are against it.

I've seen some explanation, that engines with big pistons are generating so much G forces to the piston that rod gets pulled at higher force when throttle is suddenly closed or engine hits limiter, because there is no air cushion anymore and no explosition to turn the piston to go down. This can cause lower bearing damage, as the pull to get the piston down is so great at 10k.

so actually driving at good throttle at 10k does less damage to the engine, compared to situation where the limiter is hit and throttle closed suddenly. many drag racers are saying the same thing, that throttle should not be closed totally at the end. it destroys engines.

[brent_b]

I know mine failed in the TLS upon hitting the rev limiter

[Kamikuza]

Originally Posted by JarkkoT

Nice catch, that really shows how the damage starts, so it's a rare picture. usually pics are taken after the damage is total.

is the damage only to lower shell? It's amazing that many times the damage actuall is to the lower shell and not the upper, even thou upper should get more damage, because piston forces are against it.

I've seen some explanation, that engines with big pistons are generating so much G forces to the piston that rod gets pulled at higher force when throttle is suddenly closed or engine hits limiter, because there is no air cushion anymore and no explosition to turn the piston to go down. This can cause lower bearing damage, as the pull to get the piston down is so great at 10k.

so actually driving at good throttle at 10k does less damage to the engine, compared to situation where the limiter is hit and throttle closed suddenly. many drag racers are saying the same thing, that throttle should not be closed totally at the end. it destroys engines.

Ah, that might explain why when my local shop does a 'dyno' run, they keep revving the engine with the clutch in while the rear wheel spins down ... then again, it may just be a whacky jappo thing

[pad]

Hers a picture of the upper shell
http://members.optusnet.com.au/pdnali/PICT0006.JPG

Hers the crank
It measures up at 44.98mm , The visible marks are to small to feel
http://members.optusnet.com.au/pdnali/PICT0007.JPG

Hers the other set of shells
The ID of the shells measures up at 45.06 to 46.08 mm
http://members.optusnet.com.au/pdnali/PICT0010.JPG

The Original shells are Brown
Should I stick with the brown ones or use the Yellow shells

[JarkkoT]

Originally Posted by brent_b

I know mine failed in the TLS upon hitting the rev limiter

+1

it's more dramatic to hit rev limiter with twin, because the piston +rod weights alot. four cylinder has much lighter pistons and rods. 10k for 1000cc twin is more dramatic than 20k for 1000cc four? as far as pistons go.

that oil hole area has some damage too. not sure what is the cause, is that some fatique or cavitation damage. There was one good page in the internet that showed all the damage types, but I couldn't find it now.

[brent_b]

Originally Posted by JarkkoT

+1

it's more dramatic to hit rev limiter with twin, because the piston +rod weights alot. four cylinder has much lighter pistons and rods. 10k for 1000cc twin is more dramatic than 20k for 1000cc four? as far as pistons go...

I have seen mention of soft and hard rev limiters, do we have a hard type? I thought the whole reason for the rev limiter is to stop damage to the engine, not create it