IP2 Engine powder coating

[gripper]

When I rebuilt my IP2 a couple of years ago I got Redditch shotblasters to blast and powder coat the engine. I recall it wasn't cheap and the manager said he would not be doing any more because of the work involved. It looked great but 18 months down the road and the engine looks like it's developed leprosy with the coating bubbling and lifting from the tips of the fins and other places. In view of the work involved in stripping the engine, I'm going to leave it but I would warn anybody thinking of having their engine powder coated that this is probably not the best finish for the long term. The other reason for the problem could be that despite asking for polyester PC, maybe I got something else. but then, what do I know? On a different but similar vein. A local powder coating shop blasted and coated my Commando barrels. Despite me masking the bores with thick aluminium "speed tape" he managed to damage the brand new bores, requiring a re-hone. That coating is lifting and the engine has not even been run yet. On the good side, the frame looks great! Powder coating is probably only good for garden furniture.

[rustynuts]

I suspect that they did not remove all the corrosion from your engine casings such that the powder coating did not have a stable surface to bond to. I had my IP2 wheels coated by a local company a couple of years ago and they are starting to bubble, whereas my Dominator frame was done back in 1989 and is still fine. It is difficult to find a good local finisher who takes the time and trouble to prepare your old parts properly. I have just had my IP2 engine coated via Richard. I believe the surfaces were prepared by chemical stripping rather than blasting. The fact that he gives his coating company repeat business gives me some faith that my engine finish will be long lasting.

[Richard Negus]

The process sequence I use is first to have the castings chemically stripped by a company whose main business is to remove accumulated paint from the jigs used by car manufacturers (particularly Landrover) when painting body panels as a set. The castings come out absolutely clean of paint, even down at the bottom of the fins. High pressure hot water jetting sees to that.Next comes the machining, plasma spraying and grinding for molybdenum conversion.Finally to the powder coaters who grit blast, degrease, and coat in one continuous operation, giving no chance for the surface to oxidise between operations.There are two masking operations; one for grit blasting which is removed before degreasing, and a second for coating.The 'silver' coating is actually epoxy/polyester followed by a coat of clear polyester and doesn't look as artificial as some of the bright silvers.I actually prefer the look of satin black with polished covers - but that's not 'original'.

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[Assen]

In the past BMW did some testing with aircooled motorbike-engines in painting them black. These engines did run a lot cooler. Perhaps this is a good idea for the aircooled Nortons? And, i agree with Richard, it looks good.Anyone any idea how this works? Why only with black? To me it seems filling the rough surface with paint it should hinder the cooling??? Jannes

[Dell Boy]

I have heard of people powder coating Norton barrels & then suffering piston seizures due to the cast iron fins & dimples being wrapped in an insulating jacket of paint.Even the casting dimples in iron & aluminium have a cooling value.I run my barrels with a nice patina of rust with no paint at all but then I`m far from a conkers or show stealer type of old bike rider. I dislike washing & polishing bikes, horrible chore, better to be out riding.Derek F.

[Richard Negus]

In the past BMW did some testing with aircooled motorbike-engines in painting them black. These engines did run a lot cooler.Jannes

From my school/college days, matt black is a better radiator and absorber of heat than a white surface; that's why solar panels are black. What I don't recall however is exactly how much more efficient black is versus white.We paint our domestic radiators white for purely fashion purposes as most people wouldn't want black radiators in your house.

[gripper]

If I thought I could have kept it looking tidy, I would have just gone without a coating at all, but salty winter roads prohibit that. More tales of woe on the next thread

[Assen]

I've looked up the testresults from BMW. In average the temperatur of the cilinderhead dropped 20% with blackened cilinder and cilinderhead. Not bad!But BMW thought that their custumers would'nt like black engines, and so they decided to go for bigger and more fins.Groet, Jannes

[andy588tt]

Hicommon problem with ally corrosion not being able to see it as ally turns to powder if its painted we only see the paint lifting. castings have trapped air pockets under the outer surface and with blasting the thin top layer away it exposes the air pocket when painted and heated in an oven or even with the heat from the engine the paint inside the newly exposed air pocket reach a higher temperature then on the rest of the engine surface because its not exposed to the same air flow "its like the paint boils in the exposited hole and a bubble is formed and looks bad.The only way to over come this is not blast the top layer away but to use chemicals instead and then an etching solution before applying paint I used to paint cars with a paint called two pack its very dangerous and special breathing apparatus need to be sorted. it is applied in two passes and need constant heat , A lot of messing about for a one off and the breathing gear is expensive and in view it can kill is it worth it?Send to Richard and get it done so it will last another twenty years Ride SafeAndy

[wust588]

Why not remove the powder coat and leave it as cast?I removed mine 15years ago. The motor runs cooler and (to me) looks better.

[gripper]

I was advised to go to Redditch shot blasters as they had previous experience of air cooled rotaries however, despite meticulous prep, there was evidence of blast "overspray" on my rotor chamber walls. Needless to say I was well impressed. Whilst I asked them to use the correct spec coating, as a layman, who am I to know, they could have coated with anything, whatever happened to be in the gun at the time springs to mind. I've just had a further powder coating nightmare with a local company managing to try their best to grit blast my Commando barrels including the new bores. He suggested I should have had the bores done after powder coating but judging by the amount of coating that has come off during engine assembly I don't think they would have stood up to the boring and honing process without loosing even more coating. PC is just about suitable for motorcycle frames but once chipped, corrosion can easily track inside the coating. I'm more inclined towards a conventional paint finish, Valspar or Japlac springs to mind. (with a brush)