500 Two-Stroke Tech

What type of metal are these pipes made from and what type of welding makes these blue color changes?



I think these were made by BT, but not sure.

Titanium



Don`t find a table for tiatanium, just for steel:


Around the welds the material is heated up, so it gets this blue color (TIG welding).

Based on the genuine TZ250/YZR500 silencers used these ar made are by BT. He uses these silencers.

Steel, cold roll .07 Gas welded, not Tig.

The owner.... ? cleaned them with ? Scotch bite?
and then heated around all the welds.

Bet they don't look like that years later now

I thought they might be steel. Slinger makes some steel pipes that have a dark blue hue around the welds that are very attractive. Not sure what they look like after some use, though.

I've seen some titanium chambers before, but the appearance was quite different. Here's a photo:


I've got a titanium pipe on my 4-stroke bike, and would like to get some titanium chambers that are similar in appearance. Here, the pipe has over 20,000 hard miles and still looks good.



BT- is it possible for a (titanium) anodizing shop to do this to your titanium pipes? (They don't have to be pink.)
Interesting that there are no color changes around the welds. [?]

I think the color will change when you heat it up again for a long time.
At least for steel the temperature on a 2-stroke engine will not be enough to get this colors.
4-stroke engines have much higher exhaust gas temperatures.

Can`t tell you how they got this nice colors on the NSR pipes.
Anodizing could work according to google research:
10–25nm gold, 25–40 nm pink, 40–50 nm dark blue, 50–80 nm light blue, 80–120 nm yellow, 120–150 nm orange, 150–180 nm pink and 180–210 nm green.
The higher the temperature, the thicker the oxide layer will get when doing it by heat.

By the way, your titanium exhaust system for the 4-stroke bike is a really good example for the behaviour of the gasses inside the pipe.
You can see how the hot gasses are rotating around at the wall of the pipe in the lower section
Thats what kills turbochargers if you do a bad design on intake piping

Smoker wrote:What type of metal are these pipes made from and what type of welding makes these blue color changes?



I think these were made by BT, but not sure.

Stunning pipes. So scotchbrite on my SS JL's could get me that finish?

If it is titanium, it will not last long.
I've been told that with titanium you need to closely watch a good gas shielding on front and rear side of the weld and to absolutely avoid the material getting blue'ish color.
(Due to the lack of own long time experience I can just quote other people on this. )

And again, I can't resist showing off:
I once did some test welds with 0.6 mm ti-sheet and it is possible to do that at home.
Note that it was welded as quickly as possible and thus you see almost no annealing colors.
It's just that alone the raw material for two pipes would cost 400 Euros ...

Concerning the mentioned heat treatment after welding stainless. It looks ok from far away, but for me a good weld is characterised with a narrow and parallel heat influence zone. In the pic above that was artificially widened and scrambled.
And the material was brought to a temperature it did not have during welding. I cannot rate if that's good or bad, but usually you try to keep stainless as cool as possible to avoid material reactions.
A friend of mine also builds his own pipes and he heat treated the whole stainless pipe to avoid cracks. The annealing colors cover the whole surface and he said he liked that more.
Again not my cup of tea ... I'm hammering the welds. Btw: we both build RZ350 pipes around the same time in 2012. His version developed cracks after some 7000 km that had to be re-welded; my version is still alive on the initial welds.

The hole pipe will go blue and purple if titanium if you add enough heat, this just looks like mild steel as mine look like this.

What I did with mine when they started to show some light rust is to use some naval jelly to remove the rust but it also removed the color, so I cleaned them up nice again, used a propane torch to heat up the weld just enough to have it turn blue again and then I used VHT high heat clear to seal them up and keep the look.

Gotta love these forums? lots of pipe "EXperts"

BRIAN TURFREY wrote:Gotta love these forums? lots of pipe "EXperts"

Since you are probably the most qualified pipe guy on the forum, given your history of building pipes, give it to us straight then - what do you think?

BRIAN TURFREY wrote:Gotta love these forums? lots of pipe "EXperts"

For sure, some of us are more experienced than others.

l also consider you the only living legend of 2-stroke pipe fabrication.

I'm extremely grateful that the best fabricators and 2-stroke geniuses on the planet are willing to help me with info and advice.

I know some of the things I'd like to do are a little "different", but I'm here to experiment, to learn, and to have fun.

Its all sudjective but OMG, The pipes on the Rothmans bike, look horrid, thats Fast & Furious,motorcycle style. If I was forced to choose between that Kandy color and extended silencers, it would foot long silencers each time...lol
I do like natural steel blueing, similar look you get on many of the works style pipes on moto crossers etc.. I bought a pipe from Rob Selvy for a 250r , that looks like that. Steel of course. It doesnt matter what anyone else thinks, go with what you like.

Questo vecchio rz wrote:Its all sudjective but OMG, The pipes on the Rothmans bike, look horrid, thats Fast & Furious,motorcycle style. If I was forced to choose between that Kandy color and extended silencers, it would foot long silencers each time...lol.

Yes, having mufflers sticking out a foot past the bike is not F&F style. That's more Mad Max style.

If you say that my projects are F&F style - that is a total compliment for me!

Have you seen my S2000?

Speed Freak wrote: By the way, your titanium exhaust system for the 4-stroke bike is a really good example for the behaviour of the gasses inside the pipe.
You can see how the hot gasses are rotating around at the wall of the pipe in the lower section

When the pipe was new, the small header piece was natural titanium.



The rest of the pipe had some blue coloring applied by the manufacturer.