Bearing Life Questions

[infomet]

I've read a lot about piston/cylinder problems, but nothing on bearings.
Do they typically wear out within the life of a p/c when there are no scoring issues? I guess rings get soft eventually, so how does that operating time compare to bearing life? In other words, how many p/c sets are used up before the bearings go? I've seen many bad saws, but never because of bearing failure!

 

[klickitatsacket]

on a properly maintained saw you can generally rebuild the top end 2 or 3 times to the bottom. The seals tend to go as often as the top end and many time is the cause of the top end going.

 

[GPH85]

I'm currently having to put bearings in both my modified saw and my C9. These saws are both 43 - 45 years old with "to my knowledge" original cylinders and pistons that are in relatively great shape still. The ONLY reason I'm having to put bearings in them, is because I used a liquid cooled oil in a air cooled engine that was under heavy loads, SO I don't know. BUT maybe this will help in reasoning??? Just something else to think about I guess?

 

[habanero]

One of my super ez's lost a crankshaft bearing a while back which killed the cylinder. It was the ball bearing on the clutch end, and if I had to guess, I'd say the cage that holds the balls failed first. I found a chunk of that stuck in the top of the piston and a sheared ball in the bottom of the crankcase. Funny thing was it really didn't make much noise when it went, just idled down as it lost compression and died.

Who knows how much wood that saw had cut. It was given to Dad because the guy who had it couldn't get it to run right. Dad had it for over 10 years and cut quite a bit with it, then he gave it to me and I cut quite a bit with it in two years. All this being said, I really don't think it was a wear-related failure, but rather a materials failure.

 

[oakman]

after years of running rc outrigger hydroplanes, then rc pylon racers and various other hi speed aircraft, i learned never to use a metal caged bearing. the boat motors could spin up past 25000 rpms, and you can imagine what happens when a bearing lets go, it usually lunches the whole motor. they started making hi speed, hi heat bearings with plastic or phenolic ball cages sometime in the early 90's, i think. after i started running them, my engine failures went way down. in fact, i wore out, or blew up these bearings several times with no damage to the motor. not sure if you can get them in saw sizes, but could check boca bearing or some other bearing houses. i wonder what my hot rod 066 has got in it. never had it apart, but i have had every one of my other 27 saws apart, and they all got metal caged crank bearings. the trick is to just watch em. and make sure they ain't getting loose. i don't like to see any sideplay, or end play at all. but i do have a couple old homelites with some end play that run good. tim

 

[Lakeside53]

Your 066 has "plastic" (nylon) caged deep roller bearings.

End-play is usual on some saws - they have needle rollers. If you have end play on a deep groove roller, you have problems.

Apart from the usual abuse by high reving under no load, excessive chain tension, etc, most main bearing problems can be traced to dirty air filters and poor quality gas/mix.

 

[PES+]

Your 066 has "plastic" (nylon) caged deep roller bearings.

End-play is usual on some saws - they have needle rollers. If you have end play on a deep groove roller, you have problems.

Apart from the usual abuse by high reving under no load, excessive chain tension, etc, most main bearing problems can be traced to dirty air filters and poor quality gas/mix.

Or the knuckleheads at the factory decide to use metal shielded bearings then deny warranty and say the bearings fail due to "Contamination"....yah when they heat up and come apart the shields do indeed contaminate the hole saw:greenchainsaw:

 

[GPH85]

The Homelite C-Series saws all use industrial B-1210 needle bearings on the clutch side and deep groove ball bearings on the flywheel side since there is no real load on the flywheel side.

Characteristics of bearings going out are slow acceleration with no load, can't get tuning on carb right "will run fine for a cut or two on one setting then has to be retuned to continue running", gets hot then dies and won't restart to cool down "same as bad coil", excess drag while trying to crank, a whining or rubbing noise, won't idle without some extra throttle, excess fuel consumption and of course a drastic loss of power. I'm sure there's plenty more such as seal failures or running leaner at times, but these are the main one's I've experianced.

Most of the time after tearing down a saw with these problems you will find where the clutch side bearing has been dragging and has some minor micro welding to the crank, then you will notice a decent to large amount of gritty looking black ash looking junk on and around both bearings.

I say if you buy a saw, an old saw, you might as well go ahead and go through it and put all new bearings and seals in it. Can save a lot down the road...

Greg