Painting engine barrels and overheating

[Nicholas]

Hi, I am looking to paint the barrels of my GT500 and wondered if anyone can comment on the affects on heat dispersion? I have read that painting an engine actually improves heat dispersion as the exchange of heat to air from paint is better than aluminum. But I have also been told by others that paint can cause engines to overheat and seize. So I looked into thermal dispersant coatings which are "designed" to increase heat dispersion rate from a painted surface... Is this all rubbish, am I just a victim of marketing?

The technologies come from an American company called Techline, their TLTD.

http://www.techlinecoatings.com/hi-perf ... tings.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Thoughts/opinions would be greatly appreciated!

[tz375]

It's a good question and one that has been debated for decades. The issue here is that raw shiny aluminum sheds heat slower than a matt black surface, but thick coatings tend to act as an insulator. Which is more relevant?

The answer appears to be that a thin layer of black paint is probably the best overall compromise.

[Suzukidave]

PJ-1 makes a " Fast Black " https://www.denniskirk.com/pj1/fast-bla ... /30294.sku" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false; that is said to be a good paint for air cooled engines . Good for 500F temps .

[Nicholas]

Yeah thanks again for your comments guys.

I am beginning to think that using a thin layer of heat resistive paint will suffice. With the exception of ceramic coatings, I haven't seen any charts that measure the differences between a "special" thermal dispersant compared to a standard heat resistive paint.

The principals are that paint in general is better at dispersing heat into air, so it shouldn’t crate overheating issues. Obviously using the wrong paint (insulator) may create problems and possibly making it too thick...

I might just paint them myself and bake them in my oven!

I don’t think I could go wrong with
http://www.frost.co.uk/automotive-paint ... -333g.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Or this...
http://www.eastwood.com/flat-black.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

Interestingly, this is advertised as an engine barrel paint...but the heat tolerance is far too low...
http://www.frost.co.uk/automotive-paint ... rosol.html" onclick="window.open(this.href);return false;" onclick="window.open(this.href);return false;

[Blokhead]

I've used techlines CBC2 to coat piston tops with good results. On one engine the coating stayed even though I seized it (not the coatings fault). I was playing around with stinger diameters.

[Nicholas]

I've used techlines CBC2 to coat piston tops with good results. On one engine the coating stayed even though I seized it (not the coatings fault). I was playing around with stinger diameters.

Bloody hell! How does changing the stinger cause that...thought the reflections were completed by that point in the exhaust... a reminder that tuning pipes is a dark art! I don’t want to go into coating the internals of my engine, happy to keep the power down low!

[pearljam724]

My 87 gs450's complete motor is painted black from the factory. It's air cooled. Same goes for a lot of other models.

[ja-moo]

I've used techlines CBC2 to coat piston tops with good results. On one engine the coating stayed even though I seized it (not the coatings fault). I was playing around with stinger diameters.

Bloody hell! How does changing the stinger cause that...thought the reflections were completed by that point in the exhaust... a reminder that tuning pipes is a dark art! I don’t want to go into coating the internals of my engine, happy to keep the power down low!

The stinger diameter and length sets the temperature in the pipe. Too small or too long keeps too much heat in the pipe,and things melt or seize.

[Blokhead]

I've used techlines CBC2 to coat piston tops with good results. On one engine the coating stayed even though I seized it (not the coatings fault). I was playing around with stinger diameters.

Bloody hell! How does changing the stinger cause that...thought the reflections were completed by that point in the exhaust... a reminder that tuning pipes is a dark art! I don’t want to go into coating the internals of my engine, happy to keep the power down low!

Reducing the diameter increases the back pressure which makes the pipe more efficient (and powerful). Unfortunately it also raises the temperature of the fuel, and air which is rammed back into the cylinder by the return wave. Once it reaches too high of a temp, bad things happen.

In my case, my compression was just a little too high, and my fuel quality (octane) was suspect, and then I started reducing the diameter of the stinger outlet by placing caps on the end. Every time I did it the bike went faster (my old dragbike) till about 3/4 of the way down the track it stated to detonate. It was so loud I thought a rod bearing was letting go, I should have let off, but I just kept it pinned. Thinking back this probably was not one of my best decisions. And when I say loud, this bike had open stingers, I had my Arai full face helmet on, and it was still loud.

Surprisingly the damage wasn't all that bad. The piston tops weren't melted away, but the skirts had seized slightly , and the top rings had expanded to the point were the ends had been smashed together, and mushroomed out into the nikasil cylinder liner cutting a groove.

That motor was retired, but could be repaired. Cylinders would just have to be sent out to be reniked. I didn't examine the pistons that carefully, but other than the skirts needing a little polishing, they seemed to be in very good shape. I can only attribute this to the ceramic coating on the top. If I had let off right away I don't think any damage would have been done.

I have been a firm believer in ceramic coated tops ever since. I now send my stuff out to SwainTech, and let them do it.

[Nicholas]

Thanks for the tips guys.

I'll coat the barrels as there isnt too much of a risk if the coating is thin and I keep the engine setup stock.

With the exception of the AllSpeeds and K&Ns, the rest of the engine is stock.

Actually one non-standard thing I found was that the needle clip position was at 4 as opposed to 3...could this be for the AllSpeeds and K&Ns?

I am tossing up buying a used air box and setting everything to default...I'd like to keep the power in the low RPM range, one of the things that made the T500 so popular.

[pearljam724]

Yes, sir. The needle clip position is for the aftermarket pipes. If you were to reinstall a factory box. You may or may not have to readjust the clips. Play with the notches yourself or ask other members where their clip position is for the same exact set up. If you do it yourself, only go one notch at a time until you verify how the bike runs with that notch change.

[Nicholas]

Oh, I see... Ok I'll see how it feels when its back together. Perhaps some thought was put into the mods... My friend has a stock GT500 and he reckoned mine felt like it pulled more, perhaps it was due to less/lighter parts....

One of my needles was also bent, so I will be ordering a new set...you think I should replace the needle jets too?

[Suzukidave]

.you think I should replace the needle jets too?

These can oval out from normal vibration and turn into a problem that just cannot be tuned out . A close look with a magnifying glass can sure tell .

[Nicholas]

.you think I should replace the needle jets too?

These can oval out from normal vibration and turn into a problem that just cannot be tuned out . A close look with a magnifying glass can sure tell .

Ok, thanks for the tips. I'll replace the needle jets too.

Actually should I just do the main and pilot jets too? I was going to replace all the seals and o-rings so I could do these too.... This way its all new parts...probably wise.

[Suzukidave]

Those jets dont normally have any wear but they can get clogged or crudded up especially the pilot jets with there small bleed off holes , even if you dont replace the needle jets ...a soak in some " Lime Away " will clean and brighten them up as will a brush with a old tooth brush . A close inspection to make sure they are all clear and you should be good to go .