Topic: How to bend stock headers?

[scartail]

Hi guys,

I got a 4-1 stock header for a 500, which I am going to use on my 76 550k. It bolts up, but the number 4 primary contacts the frame & the collector is very close to the belly pan. Being close to the belly pan isn't a really big deal for me. I am planning on welding on a different muffler/can, and would probably be touch that area.

Before I attempt this myself, I wanted to check to see if anyone has any tips on how to bend it, or other ideas?

Should I attempt to bend it while itis mounted on the bike/motor? Should I bend it cold? Any precautions? Stuff like that.

Thanks in advance!

[mlinder]

I didn't know there were stock 4 into 1's for the 500. Pretty sure stock was 4 into 4 for all 500's.

I would tak eit to a muffler shop and tell them hhow you want it bent. You will likely just crease the pipe if you have to bend it very much, without proper bending machines.

[Alan F.]

I think I'd proceed by mounting it up to the bike, then with a hand at the muffler I'd flex it downward a little and maybe place a shim between the pan and pipe, and between the frame and the pipe it contacts.  Then I'd fabricate some new rear mounts that hold the clearances the shims have established.  Fire it up and look for leaks at the head, tighten any leaky pipes just a little until the leak stops.  Then go for a long ride and shake the bugs out of it, stop now and then to look for issues.
Doesn't seem like you'll have to tweak it much though will you?

[alltherightpills]

One trick is to build a jig, fill the pipe with sand, cap both ends and then bend.  The sand prevents kinking or creasing.  Here is a series of images that shows how to do it:
http://niskygarage.logical.net/CB350/week2.html

[Chester345]

+1 on takin it to a shop.

Aren't muff pipes lots thinner walled than what those guys were using in pills' link?

Not that the jig approach wasn't cool, just might not work the same...

[scartail]

The problem I see with just taking it to a shop, and saying bend it.. or bending it off the bike is... i wouldn't want to misalign where the headers bolt up to the head. Maybe I should weld braces across the primaries, near the head, before I bend it. Again, only the number 4 primary is touching the frame.

If I were to bend it while it is mounted, how am loading up the studs/head? I thought about taking a torch and heating it up the primaries a little, before I put any load on.

Another idea just popped in my head (the shim idea that Alan F. mentioned)... What if I put a shim/dowel between the fram and the number 4 runner... Heat it up alittle, then tighten up the header. I don't really want to crush the tube.

I really should have pictures to share with you all. I'll take some when I get home this evening.

PS: I got the headers off of ebay, and the seller listed them as a CB500 exhaust. Really didnt' matter with me, I just wanted 4-1 headers.

[MJL]

Is it just a tube that contacts the header? If it's just a little bit, you can take a socket that is the same size as the tube, place it on the header and dent it in a bit. muscle car and hot rod guys have been doing this for years.

[scartail]

Is it just a tube that contacts the header? If it's just a little bit, you can take a socket that is the same size as the tube, place it on the header and dent it in a bit. muscle car and hot rod guys have been doing this for years.

I think that is the route I will take... I overthinking this...

Thanks for the inputs everyone!