Bending bicycle engine exhaust

Can Harm Hen

New Member
Mar 1, 2008
38
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Davis, California
Re: Bending exaust

I went to the art department workshop on campus and borrowed their acetylene torch. Did the trick, but it leaves the pipe discolored. Doesn't bother me a bit, as long as it works. :)
 

Bikeguy Joe

Godfather of Motorized Bicycles
Jan 8, 2008
11,843
236
63
up north now
Re: Bending exaust

For the best results, fill the pipe with sand, heat it cherry red in an area about 3-4" long and bend it over a curved object like a big steel pipe or other steel object about the radius of the bend you want.

The sand reduces the possibility of kinking the pipe. You will ruin the chrome.

Some have bent the pipe slightly (less than an inch to clear the pedal crank of front fenders on some bikes) with no heat, if you want to try a moderate bend (under 45 degrees) without heat, still use the other steps above.
 

paul

Well-Known Member
Dec 23, 2007
5,548
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Kalamazoo, MI
Re: Bending exaust

i personally could not bend it at all so opted to bend the crank out a little to clear the exaust which was a hole lot easier
 

cityevader

New Member
May 11, 2008
170
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Santa Cruiz, CA
Re: Bending exaust

i personally could not bend it at all so opted to bend the crank out a little to clear the exaust which was a hole lot easier
:eek: The crank bent before the exhaust! Holy mackerel!!!
Perhaps my mountain biking background has my perception of cranks trapped, but I can't even fathom bending a crank. Perhaps street bikes or cruisers are not built as stout?

You could take you're pipe to a muffler shop, not only do they have the right torch, but will also have a tubing bending tool. If they have the right die set, you could possibly bend it without heat or cracking off the chrome, depending on the amount of bend of course.
 

paul

Well-Known Member
Dec 23, 2007
5,548
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Kalamazoo, MI
lol well my pedal bicycle their is no way i would bend the crank however i only pedal my motorized bicycle enough to get it started so was not worried about it and it did the trick
 

thatsdax

Member
Feb 22, 2008
869
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www.thatsdax.com
Protect the exhaust pipe with wood in a vise. Bend it slowly. No heat needed. You may have to stand up and pull on it. But make sure you block it off with wood to not damage the chrome. Bend it slow so the chrome will not peel. Enjoy the ride...
 

Goat Herder

Gutter Rider
Apr 28, 2008
6,248
11
38
N.M.
It takes nuton to warp the flange where the pipe bolts to the moter, warped mine finally welded a new flange on top of the old one. After porting it had become too weak. Be careful.
 

Cabinfever1977

New Member
Mar 23, 2009
2,290
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Upstate,NY
i wonder if i could bend my 1 piece crank 1 1/2" so it would clear my wide engine? i know its solid steel,cause my power saw wont cut threw it.
right now im using a 3 piece crank,its falling apart,want to go back to 1 piece.
 

Outrunner

New Member
Dec 27, 2008
147
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Atlanta, Georgia
i wonder if i could bend my 1 piece crank 1 1/2" so it would clear my wide engine? i know its solid steel,cause my power saw wont cut threw it.
right now im using a 3 piece crank,its falling apart,want to go back to 1 piece.
I bent my exhaust pipe by using a MAPP/Propane torch set. They're available at
any Home Depot or Lowes for about $39.00. Just clamp the flanged end in a vise
with wood or soft jaws, heat an area about 1-2 inches long while applying pressure.
It will dull the chome, but I wire wheeled the surface very lightly and it looks fine.