Homemade exhaust?

ReelRacin57

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I would like to make my own exhaust on my maxim. I found an exhaust builder kit but it says it's for a 650. Can anyone tell me the difference between the dohc 400 and the 650. I just don't know the dimentions on the 2. I'm hoping the exhaust ports and the flange are the same dimensions.
 
They are the same. This is what I used:

http://www.lowbrowcustoms.com/xs-650-builder-exhaust-kit-for-your-chopper-bobber-or-cafe-build.html

Exhaust%20Build%2030.jpg

Trial%20Assembly%205.jpg

Trial%20Assembly%2023.jpg
 
Keep in mind that our stock pipes are double-walled. They might look like 1.5 pipes but inside they're more like 1".

All depends on what you're going for.
 
I did the math a while ago, and recently posted the numbers in another thread, but if you use 1.5" OD pipe, the head pipes should be 17" long and will result in a 9k RPM peak on a DOHC motor. In comparison, the stock pipes are much smaller and much longer, with a 7k RPM peak. Yet the engine still pulls well to 10k. If power is the goal, do the math. If function or style is more important, build safely.
 
I have measured the I.D. on both 77-79 and 80-82 sohc xs400 head pipes and get just a bit over 1.25" on both.
 
If you do want to do the math, this is one place to start: http://www.mezporting.com/exhaust_length.html
Followed up by the book they got the calculations from, "Four-stroke Performance Tuning" by Alexander Graham Bell

I keep harassing my wife to bend up some double-walled headers on the CNC pipe benders at her work but it's probably never going to happen. They don't want to attempt the double-walled bends in their expensive machines. :(
 
Looks sweet jimvonbaden. thanks for the advice guys, I just wanna make sure the fit into the exhaust ports. I tried putting a friends 650 pipes into the spair 400 max. Motor and the flanges wouldn't line up with the exhaust studs
 
Looks sweet jimvonbaden. thanks for the advice guys, I just wanna make sure the fit into the exhaust ports. I tried putting a friends 650 pipes into the spair 400 max. Motor and the flanges wouldn't line up with the exhaust studs
The XS650 kit fits perfectly, flanges at all.
 
Yeah, a set of xs650 headers will not fit an xs400 because the angles are all wrong.
But the exhaust kit isn't built yet. None of those angles are set. You can use the 650 kit and simply build it to fit your 400.

I've given up on getting the wife to make me double-walled pipes. Will be measuring some angles to get some single walled pipes bent up though. Had an idea for a 2-2 exhaust configured like a 2-1.
 
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