Crankshaft Balancer Bearing

[vasama]

Hi

So, recently, Adidasguy had a crankshaft balancer bearing fail, if I read correctly. Someone else posted a similar problem not long ago.

My question is, does anyone know of anything that should be done to prevent failure? Is this simply a life-cycle issue where the part is designed to last some time and then fail? If that's the case, what's a good mileage to go by to replace the part(s) before worse damage is made in the crankcase? How often should one inspect it (if that's possible), and what should I look for?

Thanks

Mauricio

[burning1]

If one of your engine bearings is failing, you have 3 options:

1. Repair it immediately.
2. Repair it after one of your crank, rods, and/or balance shaft are ruined.
3. Repair it after you have a nasty crash.

The balancer shaft is lubricated via passage ways in your engine covers, so it's very important to make sure there aren't any restrictions when replacing the cover gaskets. Preventative maintenance includes checking your oil pressure, and making sure your oil and filter are in good shape.

[cheetahman]

Glad you posted this, I have been wondering about the same thing.  These motorcycles seem to have an inherent weakness in this area.  I say this only because I have seen the problem reported here in this forum 3 or 4 times.  Plus if you look on e-bay there are a lot of dismantled engine parts for this model and that indicates that there could be a lot of people scrapping engines.  Perhaps we should poll forum readers whether or not this has happened to them and ask certain questions like what frequency did you change your oil and how many miles or kilometers on the bike at the time of the failure.  Anybody?

[adidasguy]

Everyone thought Junior's noise was cam shaft rattle. Maybe that's why it goes un-diagnosed. We accept a clanking as a part of the older engines. Considering he had an oil change a year ago, had only 2000 miles since then (at most) this had to be going on for a LONG time.

[cheetahman]

How many miles on the engine at total failure?

[adidasguy]

How many miles on the engine at total failure?

37,000 km (Junior is Canadian! Eh? Beer and back bacon, eh?)
At failure I was able to drive home from Vashon Island (about 3 miles, not counting the ferry ride). Seems at a down shift the top half of the paper thin "bearing" slid down. Now the shaft was digging into the aluminum at the upper right. Noise kept getting worse as it chewed up the inside of the case. I haven't looked at the other side to see if it was toast on the other end of the shaft.

On the lower picture you'll see some black RTV squeezing out from between the halves of the case (left side). Makes me wonder if the engine was split before and something was plugging up the oil port. I'll know when I get around to splitting open the case. I have to because I want to see all the damage.

[burning1]

I have 3 broken GS500 engines.

Race engine: Failed at 6K miles. Spun rod bearing, due to low oil. Crank, rod, cases ruined.
Spare engine: Failed at 23,000 miles. Spun rod bearing, unknown cause.  Crank and rod ruined, cases damaged. Tossed em.
Spare engine: Unknown mileage. Bad balancer bearing, due to wrong gasket/no lubrication. Repairable.

The engines seem to run a while on a damaged bearing - the race engine probably had 5 days and ~1000 miles of track use after the bearing damage occurred. If you catch it early, you can probably avoid replacing expensive bits.

[bombsquad83]

How can you tell that the damage was done 1000 miles before it finally fully failed?  Did you notice a difference in how the engine felt?

[burning1]

I noticed the change in feel/power on track. Came into the pits and realized the oil was low. I initially presumed that low oil had caused a momentary issue, since the bike seemed okay after adding oil. Noise manifested a few days later, but was mis-diagnosed as a top end issue.

[BaltimoreGS]

Everyone thought Junior's noise was cam shaft rattle.

If I ever dig my '89 out of storage I'll have to see if my camera can get decent audio of what camshaft end play sounds like.   I can only describe it as 6 to 10 rapid metallic clacks that comes and goes as the bike idles once warm.  It is not a constant noise, it comes and goes.

-Jessie