Exhaust on a Predator 212cc powered Rupp Roadster 2

GustoGuy

Well-Known Member
#1
I see OldMiniBikes sells an under the seat exhaust for the Predator 212cc with threaded canister muffler. Has anyone used this exhaust system in a slant engine mounted Rupp Roadster 2? It looks like I may need to bend it down slightly due to the angled mount of the engine. Would a propane torch be enough heat to due this?
 

Valocalrep

Active Member
#2
I see OldMiniBikes sells an under the seat exhaust for the Predator 212cc with threaded canister muffler. Has anyone used this exhaust system in a slant engine mounted Rupp Roadster 2? It looks like I may need to bend it down slightly due to the angled mount of the engine. Would a propane torch be enough heat to due this?
When I've had to bed exhausts propane didn't get hot enough for me without it starting to collapse on itself. I have used map gas and brazing torches with good success tho
 
#4
I know the old timers used to pack a tube with sand to keep it from collapsing on itself. Kinda messy but it does work if you pack it pretty tight
I do have 2 Robertson headers and I am very pleased with them both.
 
#5
I know the old timers used to pack a tube with sand to keep it from collapsing on itself. Kinda messy but it does work if you pack it pretty tight
I do have 2 Robertson headers and I am very pleased with them both.
And cap the ends so the sand couldn’t compress, leaving a pin hole for the moisture to escape.
 
#6
I know the old timers used to pack a tube with sand to keep it from collapsing on itself. Kinda messy but it does work if you pack it pretty tight
I do have 2 Robertson headers and I am very pleased with them both.
Sand bending tubing requires one end of the tubing to be welded shut and the pipe tightly packed with DRY sand. Tamp it tight with a wooden dowel as you fill it. Then tightly drive a wooden plug in the end, a piece of hardwood is best, and then heat it in a Blacksmith forge. You just cant heat it enough with any other source of heat. Yes a torch will heat it and it will bend but it will not be pretty. Heated in a forge it flows like a glass blower shaping glass. This was a very common practice in Europe in the 50's, 60's and 70's. All the race car exhaust was built using this method in Mom & Pop shops all across Europe. Ford built the GT-40's in Europe with parts sourced from hundreds of Mom & Pop shops. Cheap, fast, and repeatable. If you have ever seen proper sand bent exhaust tubing it is a thing of beauty.

I have a friend that has a 1965 Shelby GT-350R that was raced in Europe in 1966 and it has sand bent pipes on it. They are made of 2 1/2'' copper tubing. And it sounds oh so good. It has a slight ring to it if you listen. Almost like a bell ring. The original owner said that he had a blacksmith make them when he was racing in Europe to replace the "Pixie straw exhaust" that it came with.

Now with the use of mandrel bent tubing sand bending has become a lost art.
 
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