www.zxrworld.co.uk

Here's a bit of info with the benefit of my experiences of refreshing OEM mild steel headers. My pipes had just started to corrode slightly so I removed them last winter to respray them before it got any worse. We're talking about a few outbreaks of surface rust towards the tops of the headers, plus a fair covering of rust on the collector box. The pipes were cleaned up with a wire brush and emery paper to get back to clean metal, with the still painted parts thoroughly emeried to provide a good keying surface. This did not get the collector box area shiny metal but there was no loose rust and the only stuff that was left was light discolouration in shallow surface pits.

The pipes were sprayed with several coats of B&Q BBQ paint. This has been recommended in magazines by restorers as being both heat resistant and durable. I found that I needed pretty much the whole can to give a good covering as it is very thin, almost like it's way too thinned down. But it did the job eventually with a good finish. Note that it remains soft and will not resist knocking until it has been cured hard in use by heat, so handle with care.

The bike was then started up this spring and has been used on two runs amounting to roughly 200 miles. The paint on the header pipes cured hard with an excellent finish but that on the underneath of the collector box started to flake off and, having been caught in a shower, the rust has already started to come through the paint. I'm not particularly happy about this as the tin suggests that the paint contains a rust killer so it should have killed off the underlying rust and keyed hard to the remains. IMO if you are going to use this paint then you need to get all rust off and apply to clean metal, if necessary by sending the pipes off to be blasted. On clean metal it seems to do a great job, but it will not stick on even superficial rust.

I have now sanded off the BBQ paint on the collector box area and applied two coats of Finnegans No.1 rust killer paint. I've had that in the garage for years, I think it's now sold as Hammerite No.1. It says resistant to 300C so I'm hoping that will be ok for the collector box area. Then resprayed with Hi-Cote VHT matt black paint. Luckily I could get at all this with the sump / dogbones etc masked off without removing the exhaust again. I'll report back if this holds and is the way to go, although No.1 right along the headers where they get way hotter would seem to be a no-no, so if you've got badly corroded headers looks like they're going to want blasting clean anyways.

HTH boys and girls

Stickied & dropped into "Know Your Stuff!" section.

Top work Tirpitz.

try plasticote stove enamel, same stuf as B&Q BBq paint but better! also same as HT paint, the only difference is with HT & exhaust paint you have to bake it on at 400 degrees ( i hope u have a big oven)!! with Plasticote stove enamel you can apply it at room temp, excellent finish and you can even spray it over rust, if you can get the rust off first with the likes of Jenolite or rust rmedy (rust killer) even better!!

this is the plasticote finish

Cheers Baz, I'll try this one as a project for the upcoming winter. Kept meaning to update that thread so this seems like an appropriate time to say that the latest 'remedy' made bugger all difference. All the HT paint and the underlying Finnegans has now come off

TBH I think the issue is with the collector box area because the original BBQ paint on the headers is fine, even right up at the top where they enter the head and that area is nuclear. So why is it coming off the collector box? I'm wondering whether this area actually perhaps doesn't get consistently hot enough to bake the paint on. As you say, the instructions on the tin state that it needs to be baked on (and the temperature must stay up throughout the baking process) either in an oven or in use. If the temperature on the collector in the airstream beneath the bike is fluctuating the paint won't cure properly and will fail. For this reason the Plasticote might be a better call.

I've just had a look on the Plasticote site and it says that both their stove enamel and BBQ paint has to be cured within 8 hours of application by being got up to high heat for a full hour. Makes me wonder whether the B&Q paint should have been cured the same - and I left it in the shed all winter after painting and didn't fire the bike up until the spring. So maybe the way forward with this is to repaint the collector box and then take it for a run of at least an hour to cure it.

EDIT - well, I've just been doing a bit of internetz reading and the body of opinion seems to be that unless you get the pipes blasted and stove enamelled, if they're badly corroded most of the available spray-on paints don't last very long, including Plasticote. The headers were almost free of rust, the collector box was rusty, so I think this is why the paint in that area is failing whereas elsewhere it has held up. The car resto fraternity seem to swear by a brush-on HT paint called Black Velvet http://www.holden.co.uk/displayproduct. ... de=094.939 TBH it would be a lot easier brushing it on the collector box in situ than spraying again so I think I'll give a tin of this a spin and let you know.

think you'll find with the exhaust heating up and cooling down all the condensation collects in the collector box hence why it corrodes first

masterofinsanity wrote:think you'll find with the exhaust heating up and cooling down all the condensation collects in the collector box hence why it corrodes first

Aye, but that's the inside. The corrosion I'm talking about is the stuff on the outside.

ive heard of some places that can coat exhaust pipes in a ceraic sort of coating but its not cheap- about £150 ish for a car manifold, nearly as expensive for a set of stainless pipes. i can get you some info if you want? personally id paint it with vht paint or stove enamel as said-alot cheaper than the other options.