Is this big end bearing still usable??

[qurotro]

Hi
Got this poor 371. This poor saw was ran with BAD MIX and kinda score the cylinder.

Planing on putting new xpw p&c on it. But is this crank bearing still usable? the cage seems to wear out a bit. RED direction has some wobble(I think it is made that way?), GREEN direction no wobble.
Any ideas?



I think some acid and polishing will save this cylinder.

 

[AlfA01]

Welcome to OPE.

Good to go on the bearing. If it moves on the green arrow, it's bad. Side to side along the red arrow is normal. Good luck with the build.

Use Mastermind cylinder cleanup technique on YouTube.

Edit:

 

[Al Smith]

A little buff on that piston it should be okay also .

 

[Chainsaw Jim]

There is absolutely no need for using acid on this cylinder. Roll up a small piece of 220 grit and clean it up by hand. Same with the piston until you can afford a new one. As Al said, it'll clean up and still be usable.

 

[smokey7]

Wow that pisron has the worst varnish buildup ive ever seen. Ive seen old cart motors at 16:1 caster look way better then that. I am interested to see what the skirt clearance is now and after cleanup. Also for checking the rod bearing i give the rod a twist. Ie if looking down at the rod length wise turn it clockwise and counter clockwise. Couldnt tell you a measurement but my calibrated fingers know when there is concern with what i am feeling.

 

[qurotro]

A little buff on that piston it should be okay also .

Thanks for the reply! The scratch on the piston is pretty catchy by finger nails. Is that still usable?

 

[qurotro]

There is absolutely no need for using acid on this cylinder. Roll up a small piece of 220 grit and clean it up by hand. Same with the piston until you can afford a new one. As Al said, it'll clean up and still be usable.

But after the clean up will the compression raise up? Before I tear it apart it has very weak compression.

 

[AlfA01]

Low compression was probably due to ring wear and the scoring. After you install new rings and clean up that scoring, you'll probably find it has noticeably more compression.

 

[qurotro]

Low compression was probably due to ring wear and the scoring. After you install new rings and clean up that scoring, you'll probably find it has noticeably more compression.

Thanks for your reply! I'll see what I can do with it. Maybe ordering new caber rings is good enough.

 

[Chainsaw Jim]

But after the clean up will the compression raise up? Before I tear it apart it has very weak compression.

Temperatures high enough to melt aluminum will also weaken the rings.

 

[Redfin]

Are those wear marks on the big end cage?

 

[qurotro]

Are those wear marks on the big end cage?

Yup, on the bearing cage. But since the saw was ran with bad mix, I concerned about the crank bearings...

 

[AlfA01]

New crank case seals are about the best $20 insurance you can buy. In order to see the bearings, you can pop the cranks seals out and check the PTO and flywheel bearings. Seals sometimes lie about the status of a bearing. If the seals are really stiff, they may make the bearing feel like it's okay when you apply pressure on the crank ends.

 

[qurotro]

New crank case seals are about the best $20 insurance you can buy. In order to see the bearings, you can pop the cranks seals out and check the PTO and flywheel bearings. Seals sometimes lie about the status of a bearing. If the seals are really stiff, they may make the bearing feel like it's okay when you apply pressure on the crank ends.

Thanks for the reply! The crank bearing seems good as there is no wobble at all and rotate really smooth with force applied by hand. The big end cage bearing is what I'm worry about cuz there are quite some wear marks on it.