Zinc Chromate Plating on Carbs

[VidGameKing]

So all over the bike there are these gold-ish colored steel parts. They are zinc plated and then colored with potassium chromate both of which help reduce chances of corrosion. However on older bikes, wear caused by vibrations, friction, and debris can cause this layer to wear thin or off completely in some places. On my 2001 ST1100 it’s very obvious on the tops of the vacuum diaphragms where they have got spots of rust forming

The “proper” thing to do is have the parts sent for re-plating. Where they will be cleaned, then blasted, then cleaned again, then baked to de-gas, then etched, then plated via electrolysis, rinsed, then colored with potassium chromate. It’s not a terribly long process and if I had an immense amount of parts to do I would be tempted to try my hand at home.

But it’s really only one bike and the costs of having it done are way cheaper then fitting-out in kit for a specialized process

Or…

What else could one do? There is cold-zinc plating in the form of a grey-ish spray paint. Even a paint color that is supposed to emulate the look. The one with actual zinc provides some help, but the cosmetic stuff seems to just be a bunch of foo-foo fluff.

What else could one do to protect these parts?

I was thinking spray-paint the exterior, giving it a look similar to the Harley CV40… That will address the rusting on the outside, inside is another story. These parts can come in contact with the vacuum diaphragm, which is a sensitive rubber. To my knowledge there is no other replacement to this part. They have made what they made, no more. When the spares and gently used supplies run out our bikes will stop running.

So what can be used inside? I would worry about actual paint flaking off and impacting the rubber. So something else then, DuPont makes a dry spray lubricant. It supposedly bonds with the surface. In theory this could provide protection without impacting the rubber. DuPont also makes a silicone spray with PTFE, this might also work but it would be a “moist” surface that could attract more debris and corrosion.

I was thinking about using the CRC dry moly spray lube or graphite spray. I’m not sure how much that will prevent corrosion, but it will not stick to the rubber material and moisture should also be resisted. If it’s dry it’s not going to rust.

What do all of you do? What is the strategy you all use?

 

[Uncle Phil]

What do all of you do? What is the strategy you all use?

I just run the fire out all 4 of my ST1100s and don't worry about it ...
That's worked so far for over 1/2 million miles between them.
And all 4 still have the same set of carbs that they came with from the factory.

 

[VidGameKing]

I just run the fire out all 4 of my ST1100s and don't worry about it ...
That's worked so far for over 1/2 million miles between them.
And all 4 still have the same set of carbs that they came with from the factory.

I imagine you've looked on the inside of the covers though right? I mean that's where the mini-filter heads to...

Is the approach you've taken ride till it stops then figure it out? I'm terrified of that. I bought a set of carbs on eBay and am rebuilding them presently. I cannot be without spares...

 

[Joeywhat]

I think they'll be fine as is.

That being said I'd powder coat them if I really wanted to do something with them.

 

[Uncle Phil]

I imagine you've looked on the inside of the covers though right? I mean that's where the mini-filter heads to...

Is the approach you've taken ride till it stops then figure it out? I'm terrified of that. I bought a set of carbs on eBay and am rebuilding them presently. I cannot be without spares...

I absolutely have not taken the carbs apart - and I've got 2 1997s, 1 2001 and 1 2002.
The worse thing that happens on the carbs is you might get a torn diaphragm or the low speed jets clog from sitting too long.
Taking the carbs apart (other than for cleaning the low speed jets which just requires removing the fuel bowls) is the best way I know to mess them up and seldom get them back right.
The best thing you can do to ST1100s is to run them frequently and don't tinker with them.
The more you tinker with them, the more issues you will have.
These bikes are well engineered beyond most anything out there.
If you pay attention to them when you ride them, you'll know if something is going south a long time before it does.
And the more you ride them, the more familiar you get with them.

Example -
The last time I took one of mine to a 'reputable' Honda shop (years ago) they brought it out after some maintenance that I just didn't have time to do.
As soon as they rode it out I told the tech there was a problem - I could tell by the way it was running and the exhaust note.
I also told him what the issue was so that they could fix it - but it still took them a couple of days.
They finally took my advice and embarrassingly admitted that I was correct in my diagnosis.

The issues are keeping good oil in them, change it regularly, keep the rear splines lubed with moly, make sure anti-freeze levels are what they should be.
Watch for anti-freeze leaks (you'll smell them before you see them) and keep an eye on the water pump (usually no issue til around 130,000 miles).
Change the timing belt, the water pump, the water necks under the carbs, and the hoses at 100,000 then go ride another 100,000.
But you can suite yourself, I'm just giving you my experience not my theory.
BTW, if you plan on keeping the bike until either you or it turns into dust, I highly recommend you find a ST1100 parts bike for the stuff you can't get.
I own 4 'runners' and 4 'parts' ST1100s - 8 in total.

 

[afrymoyer]

I've had my hands inside of countless ST carburetors. White furry corrosion from sitting in a junk yard, yes. Clean it with a rag and solvent. I have NEVER seen rust on the insides of the diaphragm caps. Go ahead and clean them, but as mentioned above, leave them alone. Don't put any sort of special sauce inside there.

 

[VidGameKing]

I've had my hands inside of countless ST carburetors. White furry corrosion from sitting in a junk yard, yes. Clean it with a rag and solvent. I have NEVER seen rust on the insides of the diaphragm caps. Go ahead and clean them, but as mentioned above, leave them alone. Don't put any sort of special sauce inside there.

Rodger that, hold the spit.

 

[jdmccright]

There's not much you can do to repair the worn or corroded spots save replating them as you already noted. I would not recommend painting the inner surface. A grease or oil could be used as long as it is compatible with the rubber diaphragms. A light smear of tool oil perhaps? If anyone knows the rubber formula (viton, buna n, neoprene, etc.) it can be cross-referenced to a compatible oil/grease.

You could paint the outer surfaces with some basic surface prep/degrease. I don't think it needs to be high temp paint as they don't experience temps over 200F. A nice silver or aluminum color?

 

[VidGameKing]

The more you tinker with them, the more issues you will have.

You are not wrong. The way I see it: tinker with the spares, toss em on, see if they play ball after a ton of tuning. If they refuse to be nice, then I'll put the originals back on.

As far as riding the bike... I'll get around to it. running it for 10 or 20 min a week is all I can commit to right now. Once the bits and bobs have been swapped out and I am willing to trust the bike at speeds greater than 25MPH I might be in the same spot you're at. I've just got so much to do before the bike can be marked safe

 

[VidGameKing]

There's not much you can do to repair the worn or corroded spots save replating them as you already noted. I would not recommend painting the inner surface. A grease or oil could be used as long as it is compatible with the rubber diaphragms. A light smear of tool oil perhaps? If anyone knows the rubber formula (viton, buna n, neoprene, etc.) it can be cross-referenced to a compatible oil/grease.

You could paint the outer surfaces with some basic surface prep/degrease. I don't think it needs to be high temp paint as they don't experience temps over 200F. A nice silver or aluminum color?

I was thinking silicone grease if applying anything. Powdercoating the whole thing is not a bad option. I was toying with the thought of Alumi-Blast on the carb bodies... but decided naked is fine. The carbs themselves are not visible from the outside of the bike, just the vacuum tops...

Maybe an accent color then? lol!

 

[STRider]

So all over the bike there are these gold-ish colored steel parts. They are zinc plated and then colored with potassium chromate both of which help reduce chances of corrosion. However on older bikes, wear caused by vibrations, friction, and debris can cause this layer to wear thin or off completely in some places. On my 2001 ST1100 it’s very obvious on the tops of the vacuum diaphragms where they have got spots of rust forming

The “proper” thing to do is have the parts sent for re-plating. Where they will be cleaned, then blasted, then cleaned again, then baked to de-gas, then etched, then plated via electrolysis, rinsed, then colored with potassium chromate. It’s not a terribly long process and if I had an immense amount of parts to do I would be tempted to try my hand at home.

But it’s really only one bike and the costs of having it done are way cheaper then fitting-out in kit for a specialized process

Or…

What else could one do? There is cold-zinc plating in the form of a grey-ish spray paint. Even a paint color that is supposed to emulate the look. The one with actual zinc provides some help, but the cosmetic stuff seems to just be a bunch of foo-foo fluff.

What else could one do to protect these parts?

I was thinking spray-paint the exterior, giving it a look similar to the Harley CV40… That will address the rusting on the outside, inside is another story. These parts can come in contact with the vacuum diaphragm, which is a sensitive rubber. To my knowledge there is no other replacement to this part. They have made what they made, no more. When the spares and gently used supplies run out our bikes will stop running.

So what can be used inside? I would worry about actual paint flaking off and impacting the rubber. So something else then, DuPont makes a dry spray lubricant. It supposedly bonds with the surface. In theory this could provide protection without impacting the rubber. DuPont also makes a silicone spray with PTFE, this might also work but it would be a “moist” surface that could attract more debris and corrosion.

I was thinking about using the CRC dry moly spray lube or graphite spray. I’m not sure how much that will prevent corrosion, but it will not stick to the rubber material and moisture should also be resisted. If it’s dry it’s not going to rust.

What do all of you do? What is the strategy you all use?

THIS is not the reason your bike will fail to run now, or in the foreseeable future.

 

[SMSW]

I cannot be without spares...

I guess you will have to emulate @Uncle Phil. Just be forewarned, he rides 4 and has 4 more for parts. You've got a long way to go, grasshopper.

DuPont makes a dry spray lubricant. DuPont also makes a silicone spray with PTFE...I was thinking about using the CRC dry moly spray lube or graphite spray.

None of these are considered to be coatings that are designed to prevent corrosion. I'm not familiar with the inside of 1100's carbs, but I remember a paper describing rusting steel. The rusting process creates very tiny valleys and are almost impossible to coat and prevent the continuing corrosion. Best way to stop rust is to grind it off and then coat it with something that seals out oxygen and moisture. Those compounds you mentioned, including silly cone grease will be gone after a few miles if you put them inside the carb.

As far as riding the bike... I'll get around to it. running it for 10 or 20 min a week is all I can commit to right now. Once the bits and bobs have been swapped out and I am willing to trust the bike at speeds greater than 25MPH I might be in the same spot you're at. I've just got so much to do before the bike can be marked safe

Sounds like you would rather wrench than ride. Nothing wrong with that.

 

[VidGameKing]

Sounds like you would rather wrench than ride. Nothing wrong with that

I am guilty of taking everything apart. It was difficult when I was younger and could not remember how everything went back together. As an adult my memory is better (or is it?) and between that and manuals I’m much better at putting things back together.

Wrenching is a big reason I got this bike. Something to do, riding will be the goal but not immediately. I commute into the office once maybe twice a week.. but going out to the garage while on a call… totally something I can do!

 

[Andrew Shadow]

I was thinking about using the CRC dry moly spray lube or graphite spray. I’m not sure how much that will prevent corrosion, but it will not stick to the rubber material and moisture should also be resisted. If it’s dry it’s not going to rust.

If there is any contact with a moving part it won't do much of anything as it will be rubbed off fairly quickly. I never found it to be much good as a corrosion preventer either. It only seemed to be of any value at offering lubrication where a wet product was not desirable.

 

[Erdoc48]

I guess you will have to emulate @Uncle Phil. Just be forewarned, he rides 4 and has 4 more for parts. You've got a long way to go, grasshopper.

None of these are considered to be coatings that are designed to prevent corrosion. I'm not familiar with the inside of 1100's carbs, but I remember a paper describing rusting steel. The rusting process creates very tiny valleys and are almost impossible to coat and prevent the continuing corrosion. Best way to stop rust is to grind it off and then coat it with something that seals out oxygen and moisture. Those compounds you mentioned, including silly cone grease will be gone after a few miles if you put them inside the carb.

Sounds like you would rather wrench than ride. Nothing wrong with that.

I would rather ride then wrench. With 3 bikes and 2 cars for tinkering, that’s a decent degree of tinkering. They all run well but from time to time need a little TLC. Yesterday I had pulled the bumper off my MR2 to swap out the Stebel horn as it had gone bad (took a while for the whole job) then on the Silverwing, the horn wasn’t working (what are the odds?)…the spade connector came off one of the terminals on that- that was an easy win for me to correct as I thought it would be more involved. Now I can run them all and leave them all alone, until next time…