Removing aluminium from cylinder wall

Status
Not open for further replies.
Joined
Sep 10, 2008
Messages
464
Location
Cold Lake, Alberta, Canada
I'm rebuilding a dirtbike engine that melted a piston.
The cylinder looks good though it will need to be honed to restore the cross-hatching.

There are two spots on the cylinder wall where there is some aluminium from the piston that's been deposited. The cylinder wall isn't scored.

Will honing remove the softer aluminium or will I need to get it off before honing?
 
Is the cyl bore cast iron or an iron sleeve? If so you can probably get it off. If its an aluminum bore, i'm not sure you won't need an overbore.
 
Last edited:
In the old days, we used muriatic acid (from homeless depot) (pool products) to etch aluminum piston material from iron bores.

DON'T BREATHE THE VAPORS, they can be fatal.

The job must be done very carefully.
 
Last edited:
Most motorcycle cylinders(at least most built this century) have an aluminum bore. If it is a nikasil(sp?)cylinder,honing the bore will destroy it
 
Originally Posted By: Cujet
In the old days, we used muriatic acid (from homeless depot) (pool products) to etch aluminum piston material from iron bores.

DON'T BREATHE THE VAPORS, they can be fatal.

The job must be done very carefully.


That just doesn't make sense. HCl will attack iron. Are you sure it wasn't NaOH? Sodium hydroxide will rapidly etch away aluminum and not harm iron. Same cautions apply. Use complete eye and skin protection.

Won't a cylinder hone work?
 
What make/model/year dirtbike?

As mentionned in an above post, most recent dirtbikes have Nikasil plated cylinders (since about the early 90's and newer)
and pretty much any type of honing will destroy the finish.

If the surface deposits cannot be scrubbed off with a green ScotchBrite pad and/or surface scratches felt with a fingernail
after cleaning, it's very likely that your cylinder needs to be re-plated.

(plus if it's a 2-stroke engine, the Nikasil plating could also chip away at the edges of the ports if any honing is done)
 
Last edited:
Originally Posted By: Pablo
Originally Posted By: Cujet
In the old days, we used muriatic acid (from homeless depot) (pool products) to etch aluminum piston material from iron bores.

DON'T BREATHE THE VAPORS, they can be fatal.

The job must be done very carefully.


That just doesn't make sense. HCl will attack iron. Are you sure it wasn't NaOH? Sodium hydroxide will rapidly etch away aluminum and not harm iron. Same cautions apply. Use complete eye and skin protection.

Won't a cylinder hone work?


Maybe so but not as fast as the aluminum, i've seen this done before too. If its a few spots , applied over and over with a q tip. I've see the bores cleaned with a cloth soaked with muriatic acid for larger areas. but not in an aluminum bore.
 
Last edited:
Originally Posted By: Pablo

That just doesn't make sense. HCl will attack iron. Are you sure it wasn't NaOH?


It does work when performed with care. As to whether it damages an iron bore, it does not seem to if applied to the aluminum. Often after application of the acid, the aluminum can be scraped right off with a tool. Leaving the bore "seemingly" untouched.
 
It's a liquid cooled 250cc dirtbike. One of the Honda clones from China.

I got it for free after the original owner melted a piston. I could get a new cylinder for ~$100 but if it's easy to remove the piston remains I may as well save the $$, it's not like the bike is worth much anyway.
 
Ditto on the muriatic acid. We used it to remove aluminum from cylinder bores, and left over bearing material from toasty crankshafts. Use it outside, don't breath it. Mix up some baking soda and water to us as a neutralizer if you want to be extra safe. If you ever get rust stains on concrete floors, muriatic acid works wonders on that to.
 
Muriatic acid and ball hone.

Ball hone is fine on Nicasil. I have done it myself. Though if you can get a cylinder for $100 it most likely not Nicasil coated.
 
Status
Not open for further replies.
Back
Top