Main Bearing Failure...

Hi All

 

My KLX has covered about 2500kms desert riding. On the last ride out I had bad engine vibration and a horrible noise from the bottom end. I nursed it back to the car/trailer as I didn't fancy getting stuck in the middle of the desert, still pretty hot and humid at the moment here in Dubai.

 

Stripped the engine and found that the left hand main bearing has failed, I'm going to replace both main bearings. The crank, big end/little end both seem fine. The piston and barrel both look fine. So total cost should be a pair of main bearings and a gasket set. 

 

My question is....Is it normal for main bearings to fail before the crank?

 

Thanks, Dave.

 

Not unusual for a bearing to fail first but at only 2500km id say your got one made on a Friday arvo. There's no sand in there?

Oh yeah check your oil screen too for silican as its a known issue for staving oil and bearing probs

Edited by pantera66

No, there wasn't any sand in the engine.

 

To be honest with all the vibration and horrible grinding noise I was expecting there to be bits of metal / debris in the oil but it was perfectly clean.

 

When I stripped the engine I did notice that the Kawasaki factory had been a little over enthusiastic with the silicone sealant!

 

All the best, Dave. 

Is that bearing a NSK made unit? I would be interested to say what the manufacture thinks about it failing at 2500km! Ask and see if you can get a free replacement. Check out this link http://www.nsk.com/services/maintenancerepairs/maintenance.html should tell you what sort of failure and give an idea on what caused it. The life of that bearing should be many multiples of 2500Km. You need to know why it failed to make sure you have the problem that caused it to fail sorted or the next one will go much the same. Bad bearings from high quality makers are extremely rare and I would not be putting it down to that without having a very good look for another cause.

 

Post us a pick of the failed unit for interest sake.

 

cheers,

Tanis

Hi Tanis, thanks for the information.

 

To be honest I bought the bike second hand, so I don't know what may have happened before, I can see that the crankcases have never been split before. It had done 2000 kms when I bought it and I've done another 500 kms on it.

 

I'm just waiting for my flywheel puller to arrive (mail order from USA) before I can get the bearing out.

 

I'll get a photo of the bearing once I get it out.

 

All the best, Dave.

What kind (brand, viscosity) of oil do you use in that engine? Is your oil or air filter genuine Kawasaki or after-market?

Mine failed at pretty much the same km from memory. Mines an 08 and dealer said that from 09 on they had changed the part no. of this bearing. Not sure if that's true or not. That said now at over 7500km and no further issues.

What kind (brand, viscosity) of oil do you use in that engine? Is your oil or air filter genuine Kawasaki or after-market?

I use Mobil Fully Synthetic 15w-50.

 

After market oil and air filters.

 

Regards, Dave.

Dave, it could be sand ingress. Air filter would be the obvious culprit. I haven't seen a rebreather on my engine but maybe it is worth exploring the sand ingress route?

I've completely stripped the motor and split the crankcases but no sign of sand anywhere, I'm pretty sure it's just a faulty bearing.

 

Cheers, Dave.

I've completely stripped the motor and split the crankcases but no sign of sand anywhere, I'm pretty sure it's just a faulty bearing.

 

Cheers, Dave.

try getting somthing for your trouble i know the bike is second hand but see if the company who made it is intrested? post up some photos of the bearing if you can im intrested it what kind of damage its got! There is no way is should fail with that many km on it.

@Tanis, thanks for suggesting that, but it would be a complete waste of time here in Dubai, I'm afraid support from the Kawasaki dealer is very poor, same with most of the bike dealers here. They're only interested in selling bikes and getting support, spare parts, etc. is very difficult, frustrating or even impossible. 

 

Most of the people that ride bikes here source spares via the internet from the United States.

 

Anyway, I'm happy to say it's rebuilt now and I've put 6 hours of desert riding on it without any problems.

 

The failed main bearing was left/magneto side, the surface of the inner race was damaged. All other bearings were fine other than a few marks on the scavenge pump rotor.

 

All the best, Dave.

Inner race was damaged? Sounds like it was fitted incorrectly.

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