Scooterotica

Had a wee chat with a mate yesterday about exhausts and what I was considering for the RB250.

I had expressed interest in a certain stainless exhaust, to which my mate was saying about heat dissepation and the brittleness of stainless.

Now I have heard about this before, but if it's so bad, why would certain dealers make top class performance exhausts...stainless?

I don't want a chrome exhaust, but I don't want an exhaust that's going to have rusty crud in no time and look a mess.

Bob, its the U bend that needs to be mild steel really, as this is the part that gets the hottest. That's if you can find a SS exhaust with a mild steel U bend. (Speaks with authority as had two SS U bends snap at the manifold face)

Cheers.

Sounds like I'm going to struggle.

Stainless has a habbit of cracking about 3mm-5mm from the welded seam, this is because the chrome in the stainless makes the stainless very hard\brittle as the weld cools, (check any book on welding such as those by A.C.Davis).

As dapper says the U-bend is the part most prone to cracking but that applys to any exhaust.

If you do want stainless keep it mounted on rubbers etc.

How about Titanium £300-£500, never rusts as light as aluminium, as stong as alloy steel, fatigue resistant, used on all the F1 bikes. But the price??

Thanks for the reply Steve.

Mmmmm titanium. Nice but out of my league.

I don't understand why top tuners/dealers swear by stainless pipes if they are prone to defects?



I think I'm going to go down the plain black route.

Well, if you live and ride your scooter anywhere near the sea with onshore prevailing winds a stainless exhaust lasts a little longer. That said, I prefer mild steel which can be hi-temp painted or ceramic coated. My DevTour has held up remarkably well over two years, salty air and bumpy West Cork Irish roads. It did snap off at the stinger but that was from hitting a particularly bad pothole but it welded up good as new.

Hmmm titanium ,just think of the lovely shower of sparks on corners.

There are coatings which are applied internall and externally which will stay good for years and enhance performance as well try this for a start Cermakrome looks about right.

http://www.camcoat.u-net.com/Coatings.htm

Over the years I have been lucky enough to go to a lot of race teams, cars and bikes. Not once have I seen any of them using stainless steel. It does not heat up and cool down at a very good rate. This is what I was told the last time I went to Renault F1 anyway. Steel or titanium heats up and cools down at a much better rate. This helps to prevent cracking. The main reason people make scooter exhausts out of st/st is that they are easy to keep clean and polished and they don't rust. Most of the F1 teams are going over to " Inconel" this seems to go up to a higher melting point and it is a lot easyer to weld, or so I was told.

Steve, Bilko or wack 63 I still have a massive amount of titanium sheet at home if you want to have a go at making yourselfs an exhaust. Just send me a p.m. and you can have enough to make a pipe, just pay the p+p. Give it some thought guys.

i was quoted over £1500 , and that was by a mate in f1 !!! those boys dont use titanium , its inconel , which makes everything else seem like lead !!! i personally wouldnt touch a stainless two stroke exhaust , but thats from my engineering background , but you pay your monies so you take your chance !!!! :bald:

tzr.steve wrote:Stainless has a habbit of cracking about 3mm-5mm from the welded seam, this is because the chrome in the stainless makes the stainless very hard\brittle as the weld cools, (check any book on welding such as those by A.C.Davis).

As dapper says the U-bend is the part most prone to cracking but that applys to any exhaust.

If you do want stainless keep it mounted on rubbers etc.

How about Titanium £300-£500, never rusts as light as aluminium, as stong as alloy steel, fatigue resistant, used on all the F1 bikes. But the price??