Commando barrel temperature and suitable paint

Any engine laquer, doesn't have to be the VHT exhaust stuff. Don't put it on too thick; it is supposed to be air cooled.

I'm still using a tin of Hermetite "Pot Black". Finish is more satin than the original gloss. Don't know whether it's still available. Halfords sell engine laquer in various colours. Screwfix sell some black BBQ grill paints that probably work ok.

Agree with Stan,   Don't powder coat.  Some do it and get away with it.  Till one day the engine overheats for whatever reason  ,then it is much more likely to seize ,then break a rod and wreck the motor. 

Re comment about powder coating, I can understand that in principle a thick coating may prevent optimum heat transfer to the airflow, but it has been used for years.  My first Mk3’s cylinders were powder coated by Draganfly M/Cs in the early 1980s without any obvious adverse effect and my current ones have recently been powder coated through Norman White, albeit these have not been fitted yet.  I wonder what practical difference powder coating actually makes, assuming it is not a really thick layer that compromises air flow between the fins?

The cylinders get hot without powder coating, in particular the region between the two cylinders for obvious reasons.  The high temperature is evident by the condition of pistons, where there the skirts take on a really dark brown appearance on their respective inboard surfaces. I still have my original Mk3 pistons and they are pretty much identical in their burnt brown inboard skirt appearance to those removed from my current Mk3 engine, both STD bore and with the original factory applied cylinder finish, whatever that was - anyone know?

 Andy

Somewhere on YouTube is an experiment on Commando barrels to show the difference between bare cast iron and powdercoat when the barrel is heated. No discernible difference detected.

I think the problem with powder coat is the thickness  may vary with who does the job.,And there will need to be a lot of masking up.I once had a Dommy seize hard at 90+ in the fast lane of the M1.  And it managed that without an insulating jacket.  I play safe now.

I’ve used PJ1 with good results. I used the satin finish but it comes in gloss as well. It’s been quite durable too.

Hammerite smooth black or satin black are pretty effective. Some of the high temperature paints seem to disappear following the first rain shower.

Hi, on the very good engine rebuild video by Mick Hemmings he says he uses PJ1 for barrels and puts it in the oven to harden

I put Pot black on my barrels about 25 years ago , been in use since then with a couple of touch ups. , 

PJ1 is one of the best and putting the barrels in your oven is not always allowed. Let it cure for 48hrs keep the barrels clean while fitting, do not degrease until you've given the motor at least couple of good hot runs out.

Hi,

Just to make it simple. I`ve used usual black paint applied to the cylinder of my NSU Supermax with a paint brush. I do not believe that a Commando cylinder gets much hotter than an aircooled NSU cylinder. But mowadays I use paint  from the spraycan up to 600 degree C made by "Dupli Color". "Supertherm" is the product name. Its not why it seems to be better. Its easier or may be I get lazier?

Regards Uwe

I've used Rustoleum Hard Hat 750°C Black and Aluminium with good long term results. Recommended by Pete Lovell.

The barrel on my 16H (which should run hotter than a Commando) reaches 220C (430F) close to the exhaust.

Hi the best paint for barrels I have found is the one below..... I have used this on my commando and my Triumph and My BSA and it has been on some years now and still gets commented on where ever I go so I would use this again and again.

Simoniz Engine Enamel 

Its on ebay at about £10 

Hi I used a aerosol gloss black on my BSA barrels 2 years ago still look good and no peeling or flaking .havnt done my commando ones tho .