390XP - How to prevent bottom end failures?

[Fordiesel69]

Ended up aquiring a new old stock, never gassed, 2021 model year 390XP. I am planning on doing its first start and break in pretty soon. My question is, how do I prevent or slow bottom end failure? When I google a lot of chainsaw models, I am not seeing a ton of bottom end issues with the 545, and 555 like you'd see with the 550XP and 562XP. Yes there are some here and there but not very many. Im am not digging up many bottom end failures with the 288, but am seeing quite a few photos and threads with regard to the 390XP's. Conversely I have never seen or heard of an echo cs-670 / 680 bottom end failure. I simply can't find any examples online.

I am skilled with how to prevent top end failures, which is to detect and shut down asap if it goes lean (air leak), and to keep mixture dialed in to four stroke out of the cut. But with bottom ends, how would one prevent failures?

Because I always wanted one of these, and plan to make this a lifetime saw, I want it to last. It wont get used much but when it does it will be used very heavy and will have its 36in bar buried.

https://www.arboristsite.com/threads/husquvarna-390-xp-pto-side-bearing-failures.244457/
https://opeforum.com/threads/husqva...cement-and-a-few-things-unique-to-390s.18690/

 

[MacAttack]

Run a quality FD rated oil at 32:1. Keep the air clean going into the engine. That's what I'd do!

 

[wcorey]

Only things I can think of is to minimize running high rpm's/piss revving and run a high ratio of (FD rated) mix oil.
Maybe not run aggressive, bumpy chains.
I've seen a couple of these with the bearings spinning around in the case, seems like it would be more of a manufacturing tolerance issue as opposed to abuse.

 

[Fordiesel69]

I have a local example of one that is running, I might be able to see it apart if I stop back, but it has a growling (dry bearing) sound on the flywheel crank bearing. No knock or tapping just the dry groan. I wonder what would cause that? They are going to do a bottom end refresh as the top end was not harmed (yet).

 

[Gord404]

built or rebuilt a lot of them- most of the cranks are ok- but on some the pto bearings didn't fit tight enough on the crank and spun causing an air leak and an unsalvagable crank in some cases- for 30$ i usually replace that bearing and if the crank idoes not pull in tight on the bearing i toss the crank and yes i have seen the odd broken con rod- one broke off at the big end and hit the top of the cylinder - still bolted down but to my suprise it busted the cylinder from the base- easy take down- like I said I have done lots of these saws and most of them are ok

 

[Fordiesel69]

built or rebuilt a lot of them- most of the cranks are ok- but on some the pto bearings didn't fit tight enough on the crank and spun causing an air leak and an unsalvagable crank in some cases- for 30$ i usually replace that bearing and if the crank idoes not pull in tight on the bearing i toss the crank and yes i have seen the odd broken con rod- one broke off at the big end and hit the top of the cylinder - still bolted down but to my suprise it busted the cylinder from the base- easy take down- like I said I have done lots of these saws and most of them are ok

Any suggestions how to make them last so I dont need to get inside?

 

[J D]

I'm not sure what year it changed, but the later saws had an updated crank to address some of the issues. I'd look into that & you may find you have very little to worry about

 

[Fordiesel69]

Its a 2021 datecode. So id imagine its near end of production at least from what I hear.