Powdercaoting question?

[chpzenker]

Guys, what do you think about powdercoating the engine? and what about the carb bodies??

[natemoen]

Lots do it. I would like to but don't have the cash. Make sure your engine is good before you invest though.

[James England]

Guys, what do you think about powdercoating the engine? and what about the carb bodies??

I had a long talk with a powder coater the other day and also a bloke who has frames powder coated. They both say that the thickness of powder coating often interferes with bolt holes, threads, brackets and tolerances of one sort or another. On a particular chain driven bike, they had to chip powder coating off in order to get the chain tensioners to go onto the swinging arm.

I dread to think of what powder coating would do to allen bolts holes in engine casings, car threaded holes etc.

On a Triumph Bonneville, I once had the casings chromed. mmm.... they did both sides and none of the bearings would go back in... the kickstarter shaft wouldn't go through etc etc. Wouldn't powder coating do something similar??

[natemoen]

I had a long talk with a powder coater the other day and also a bloke who has frames powder coated. They both say that the thickness of powder coating often interferes with bolt holes, threads, brackets and tolerances of one sort or another. On a particular chain driven bike, they had to chip powder coating off in order to get the chain tensioners to go onto the swinging arm.

I dread to think of what powder coating would do to allen bolts holes in engine casings, car threaded holes etc.

I would say that any quality powder coater (not just someone who does powder coating) would fill those hose as a part of the prep work so that the powder coating could not get in to the threads and would not be a problem. Especially the mating surface of the head bolts in particular could easily be covered so that there would be bare aluminum still showing as to not interfere with the head torquing.

[Ken Talbot]

You can get a wide assortment of high-temp rubber plugs to stuff into holes where you want to exclude the powdercoat and flat surfaces can be handled much like painting would be, but with a special polyester masking tape.

[62xs]

I did mine. The problem is the butterfly seals.

I fry-ed the nylon ones under the spring but that was easily replace at ace they had the right size.
You do need to think ahead on a lot of things to do it right.
there's a picture of it on my photo bucket list.

[cywelchjr]

I don't care much for a lot of what those guys on american chopper did, but they did powdercoat a lot of parts. What I learned from watching is if you powdercoat anything with threads, your going to have to run a tap into the hole to clean out the threads, and any holes with tight tolerances will have to have a drill bit run through them to clean out the hole. None of those issues are insurmountable, and things like the bolt holes on the side covers of the engine appear to have plenty of slop to make it a non issue. Of course there are parts of the engine I would NEVER powdercoat (like the inside and of course the contact surfaces).

Now, as for chroming, I'm not sure it's even possible to chrome only one side of an item, unless it sealed and could be immersed so that only the side you want chromed is covered. What with how hard it can be to get good adhesion of chrome to aluminum, I'm not sure it would be a good idea to do that anyways.

[crazy steve]

As someone who loves powdercoating and will use it pretty much anywhere I can, keep in mind that coating precision/machined parts can get involved.

First, remember that you have to totally disassemble whatever you're coating. For the carbs, that means removing every part except for pressed-in bits; the throttle shafts will have to come out and all the linkage will have to come apart. Same goes for any motor parts; no plastic, seals, gaskets, rubber, bearings, or bushings should be left in place as the cure heat will damage them (bearings/bushings can take the heat, but unless you get all oil out of them, it will turn into a gummy mess that can be impossible to get out). And failure to disassemble will quite nicely 'glue' the parts together and they may not be so easy to get apart.

I did a set of carbs (including all the linkages), and other than keeping the coating out of the internal areas had no issues. For threaded holes, I only plugged the ones I didn't have a tap for as I've found it easier (and gives a better job) to just 'chase' the holes with a tap after coating. For cast parts that have been exposed to oil, you have to thoroughly clean them, then 'pre-cure' them to 'boil' any remaining oil out before coating. You may have to do this multiple times until there's no more showing up. You also have to remove any corrosion, as it will blister the finish when cured. Cast aluminum parts are particularly prone to this, so I 'pre-cure' these even if I think they're clean. I can't stress this enough; aluminum can't have any corrosion or it will show up as blisters when cured.

If you're planning on doing this yourself, figure 3-4 days to prep/coat a set of carbs. You'll have to blast every part; I did the carb bodies by fully stripping and cleaning them, installing the bowls/tops and taping off the inlet/outlets, blasting them, then disassembling/recleaning/masking them before coating. If you're having this done, expect to pay for the labor. Very time consuming...

Same thing goes for motor parts; prep is everything with powdercoating. I don't hesitate to use it for frame/suspension/brake parts (with care taken to keep the coating out of critical areas) but many commercial coaters don't take the time to properly mask parts which has led to problems with 'fit'. One place the stuff is great is battery trays; a good heavy coat will stop corrosion dead in it's tracks.

To be honest, I probably wouldn't coat the whole motor; just the easily removable covers. Painting the cases/barrels/head is a bunch less labor-intensive and more forgiving of mistakes....

Anyway, my .02....

[chpzenker]

Thanks for the info and I am getting my own setup to start powdercoating. Got an oven and a gun from Eastwood. Looking forward to useing it. Going to get my blast cabinet finished this weekend and hopefully ready to shoot some pieces. I will be using plugs and heat resistant tape to keep the powder were it belongs. I will post some picts as soon as i can. may be a week or so.

[crazy steve]

Sent you a PM....

[62xs]

some of the things I have found to be useful are cooking bags, my wife has some kind of paper she uses for baking these are good for covering big holes and the parts separate easily. Use the paper like a gasket leave it stick out a 1/4 in.

[natemoen]

some of the things I have found to be useful are cooking bags, my wife has some kind of paper she uses for baking these are good for covering big holes and the parts separate easily. Use the paper like a gasket leave it stick out a 1/4 in.

parchment paper?