Lurker's V-twin build

motorhedfred said:
Seriously ? I think I see a few tight 90s here. Plus, his flare up to a larger ID as well.

MHF
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yep curved 90 but not L 90
this
Briggs_performance_exhaust.jpg


not this
images


the most flow happens when the pipe stays the same size thru a curve
look up mandrel bending
 
Lurker .. you don,t want to use that pipe fitting .
i used one as a temporary pipe on a 97cc 4 stroke project i did ( temporary !! )
Those fittings ( although they have a nice formed radius ) are still almost like a 90 degree angle ( you loose about 10 percent flow ) even worse they duild up a lot of heat .. i mean real hot .

What i did after that was go to the hardware store . bought a stainless steel bathroom grabrail ( the ones with a flange at each end - to screw to the wall . )
Make a flange that fits the motor .. cut the grabrail as needed and weld it up .
it has a pretty tight bend ( about 2 inch radius ) way better than that 90 degree fiting for sure .
worked great ... doesn,t build up nearly half the heat ( and flows way better )
.. just sayin
 
He is not useing a stright 90 it is 1" and increases to 1 1/4" that is perty free flowing if you ask me. They have been useing that kind of elbow on Briggs and Kohler engines for years and didn't seem to be any problum...........Just my thought..........Curt
 
Lurker said:
Thanks for the tip cobra, where can I get some of that stuff?

taylorv those pieces are steel, I know better than to weld galvanized. But thanks for the concern.
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Welding supply stores. It's used to spray on the nozzles of wire feed welding heads to keep them clean. If you spray the metal you are welding to it keeps them clean as well.
 
Lurker, I wouldn't use that fitting if I were you. Brass has a melting point of 900 to 930 degrees. Steel is in the 1500 degree and above range. The average exhaust temp at the hottest point is 900 degrees if it starts glowing. Even if it doesn't liquify it could soften and ooze. See if you can get a fitting like that in steel so you wont need to deal with problems like this. Oh, melting point of copper is around 1083 degrees.
 
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I made my exhaust out of metal electrical conduit. It's cool to use because you can bend it quit easily and they have pre-formed bends as well. Easy to work with.
 
I am with cobra...I have welded conduit may times and if you look at some of my builds thats whats used on the header part of all my 2 stroke exhaust. Shoot I have even been exposed to that great stuff called Phosgene gas. I am still alive...maybe a few less brain cells...but what the ****....lol
 
I have even welded gal pipe and survived (no instant death), but i did grind as much gal coating off as possible and a fan like Cobrafreak said and i have absolutely no side effects to speak of........ what were we talking about again????????????.....................LOL
 
Har, when I got a mig and was teaching my self to weld, first thing I made that actually did some thing was a tail-pipe made from galvanized conduit. Luckily had the garage door and back door open and the fumes blew away from me really well. I did not know how sick the fumes could make you before that. Didn't get sick at all. Then welded copper to it which of course can't be done. But not knowing that, went ahead and did it. So then beat the weld with a hammer to prove it held. Took me two whacks to realize it was doing the copper no good, lol.
 
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