TOPIC:

Taking apart the GPz engine and there is white corrosion on the bolts. I know I can wire wheel these clean but is there a way to clean off the corrosion without damaging the coating on the bolts? I assume the way to prevent future corrosion is liberal amounts of anti-seize?  
 

You could try cleaning one with a brass brush (rather than a steel brush). Brass is softer than steel and is less likely to cause damage.

I like to use a brass wheel [in the cordless drill] with longer bristles to clean non-steel parts of the bike, like aluminum surfaces. Longer bristles will flex and will effectively be softer than short bristles.

Folks on this forum and elsewhere have mentioned that using anti-seize will probably cause you to overtighten the bolts. IIRC they were meant to be assembled dry, and the anti-seize acts like a lubricant when tightening so more force is required to achieve the torque spec in the FSM. But you'll want to explore that yourself - my memory isn't always great. 

Looking at the amount of rust on those bolts it looks like the coating has already failed, you could clean them off with a wire wheel and then you could "blue" them (a process used by gun makers to prevent corrosion

I would try carb dip first as a non-abrasive solution.

The factory finish is zinc, with an olive drab dark chromate dip.  A brass wire brush may be useful, but the plating is already damaged, so there is only so much you can do.  Personally, if the heads still look okay, I'd wire brush the white corrosion off, then install using grease, or better yet, an anti-corrosion compound.  To fix the hardware properly, the old zinc would have to be removed, or at least the black chromate layer, then re-zinc plate everything yet again.  

Ok. I think I'll just clean off the corrosion as gently as I can. Nessism, what anti-corrosion compound would you recommend? 

Could phosphoric acid be a option?

wrote:

Could phosphoric acid be a option?

It might be. I have some so maybe I'll try it on one of the bolts I'm going to replace. Good call. 
I'm thinking I'll give the 'ol ultrasonic a try too. 

Fluid Film makes an excellent corrosion protector.

Regarding phosphoric acid, it eats zinc.  I wouldn't use that stuff unless you want to strip the fasteners down to bare metal.

Never use any acid to clean these bolts it may result in hydrogen embrittlement and cause the bolt to fail, just lightly clean the threads and install DRY.

wrote:

Never use any acid to clean these bolts it may result in hydrogen embrittlement and cause the bolt to fail, just lightly clean the threads and install DRY.

I'm not an expert on this subject, but from what I've read, hydrogen embrittlement is mostly a concern with high strength fasteners,145ksi tensile strength and above, not the type used outside the engine on our KZ bikes.

For example, a Japanese bolt with a "7" on it is roughly the same as a SAE grade 5 fastener (the type with three hash marks on the head,) and those are rated to about 120ksi tensile strength.  "9" bolts, similar to SAE grade 8,  would be affected, but those are typically limited to things like cam caps, and they are not plated.  

And BTW, I've got a Caswell's Plating zinc kit and use acid all the time.  Sometimes I'll strip the fasteners in HCl if they are really grungy.  If the fastener is in decent shape, I'll sometimes bead blast and wire wheel before plating, to save time.  And, actually, I think the plating process itself causes hydrogen embrittlement, far more than the cleaning and pickling process.  That's why high strength fasteners like rod bolts, APE engine studs, and similar are black oxide coated.  This doesn't damage the metal.  Black oxide is crap for rust protection though.  That's why GPz's use zinc with chromate black.

I don't think hydrogen embrittlement would occur.  From what I remember from my university courses in welding technology hydrogen embrittlement occurs when a welder uses a damp rod while welding steel.  That's why they use warming ovens for welding rods.  Our prof had a famous story about a welder on a nuclear power project that stored his polish sausage in the welding warming oven to heat it for lunch, causing the rods to become damp.