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Old 12-25-2015, 06:31 PM
Loki Loki is offline
Motorized Bicycle Newbie
Join Date: Dec 2015
Location: departed forum
Posts: 17
Default Homemade MB Exhaust Flange - drawing

An idea for those who desire a more hands-on approach to making /
welding up their own motorized bicycle exhaust flange/ header.
Sometimes the factory exh. flanges just don't hold up.

Your local hardware store likely carries 1/8" thick X 2.5" steel washers.
Most already have a .750" diameter center hole.
There are also 3/16" washers; make sure they're at least Grade 5.
These washers are quite heavy duty and will suit the purpose.
Avoid cad plated soft washers for MIG use.

*Hack, chop, drill your way to a heavy exhaust flange that will support nearly
any diam. tube you need.
Factory exhaust tubing runs 22-23mm [7/8" OD] with approx. .080" wall.
The ones I measured run .750" ID.

Included is my drawing for a DIY exhaust flange.
The job is easier with calipers, a drill press & cutoff wheel.

To extended the header use 3/4 inch [.750" OD] black plumber pipe - its super heavy duty.
Threaded 3/4" pipe welded to the front half, is ideal to extend the BGF Voodoo pipe (from center nut to rear end).
That heavy 3/4" ID threaded nut can save a lot of assembly time.

B Method: trace out an exhaust gasket & proceed to *H/C/D.
Attached Images
File Type: jpg Exhaust Flange MB.jpg (118.3 KB, 84 views)
File Type: jpg Hard washer IMG_1199.jpg (100.2 KB, 51 views)
File Type: jpg Mockup 1.5 in. mount +Pipe IMG_1177.jpg (161.9 KB, 79 views)

Last edited by Loki; 12-25-2015 at 07:44 PM. Reason: add pic
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Old 02-02-2016, 06:49 AM
Agreen's Avatar
Agreen Agreen is offline
Motorized Bicycle Elite Member
Join Date: Feb 2013
Location: Goose Creek, SC
Posts: 622
Default Re: Homemade MB Exhaust Flange - drawing

Thank you Loki, this is fantastic!

Using this I can ride the bike while designing a new exhaust instead of hacking up the old exhaust and keeping it down until completion.
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diy exhaust flange

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