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This old 550 crankcase...

Posted: Sun Jul 02, 2017 2:31 pm
by pjac
Don't know much here, this is my first post on Sundial!! Hoping someone can help...

If I start with this... could I clean the surface rust off the crank and make sure the bearings are good and leave it together? Take a chance and not split the case? Is there a way to tell if the inner crank seal is good? Etc... Or am I talking crazy?

Don't mind splitting and refurbing if necessary. Will the case areas around the crank need attention?

Image

Re: This old 550 crankcase...

Posted: Sun Jul 02, 2017 3:03 pm
by Clifford
Split the cases and start from the beginning!

Re: This old 550 crankcase...

Posted: Mon Jul 03, 2017 3:55 am
by rngdng
I doubt that the crank is good with that much water and crud in there.


Lane

Re: This old 550 crankcase...

Posted: Wed Jul 05, 2017 8:49 pm
by pjac
I suppose if the journals have any marring on them at all then it might run a resurface job up past a reasonable cost point. Back to the drawing board...

Re: This old 550 crankcase...

Posted: Thu Jul 06, 2017 4:17 am
by rngdng
pjac wrote:I suppose if the journals have any marring on them at all then it might run a resurface job up past a reasonable cost point. Back to the drawing board...
In a crank rebuild you can replace any bad bearings, and the seals. Where the crank contacts the cases (the journals) is not a big issue like it would be with a car or many four-stroke bikes.



Lane

Re: This old 550 crankcase...

Posted: Thu Jul 06, 2017 8:44 pm
by pjac
So, that old nasty crank and cases are not too far gone to be used again if the crank was rebuilt with new bearings and seals and trued up?

Re: This old 550 crankcase...

Posted: Fri Jul 07, 2017 1:56 am
by Alan H
pjac wrote:So, that old nasty crank and cases are not too far gone to be used again if the crank was rebuilt with new bearings and seals and trued up?
No. Cases media blast and cranks can be refurbed. Clean it as much as possible before the crank builder gets it.

Re: This old 550 crankcase...

Posted: Fri Jul 07, 2017 11:44 am
by rngdng
pjac wrote:So, that old nasty crank and cases are not too far gone to be used again if the crank was rebuilt with new bearings and seals and trued up?
Good news!! They can be fixed.



Lane

Re: This old 550 crankcase...

Posted: Sat Jul 08, 2017 6:30 am
by pjac
Thanks Gents! That is good news

Re: This old 550 crankcase...

Posted: Wed Jul 12, 2017 5:36 pm
by Vintageman
If you have rust on the connecting rod surfaces (Big End - Little End), The rods are no good, roller bearing and crank pin as well could be rust compromised. Sure it would run for while but it won't be long before it gets noisy and goes bad or throws roller needle about as you rev it up

Rust is the worst thing for cranks even a little if on precision surfaces is a problem sooner than later. The bike can look nice on the outside, but for example if the crank wan't turned for many moons, those mating surfaces grab moisture a little at time causing tooth decay... I mean rusting decay weakening the enamel ... i mean metal surface. The one downside of two stroke is they required roller bearing for lubrication. Those have large air gaps where air brings along moisture and the few contract surface rust first even if no liquid pored in. Your case looks like liquid did get in to crankcase, not just humid air.

Re: This old 550 crankcase...

Posted: Thu Jul 13, 2017 4:44 am
by Suzukidave
You may be better off finding a good crank on Ebay , with new rods , bearings and seals your going to be in for over $500 i bet :shock: