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Discussion Starter · #1 ·
I’ll be installing Mikuni VM32’s and would like a more free flowing system.

As I understand it, the stock headers have an outlet outter diameter of about 43mm... Meanwhile, the closest diameter straight pipe I can find is 1 5/8” (or 41.275mm), so just a tad too small.

I’m gonna stretch open the tips a tad just to be able to fit over the stock header outlets, and hoping the slightly decreased size of the pipe won’t affect performance since it will be much more free flowing than stock mufflers overall, ya?

I’d like to run straight pipes all the way back past the rear axle with shorty mufflers at the tips.

Does this sound like a solid setup for a 1972 CB450 with Mikuni VM32’s?
 

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Some 27" Straight core reverse cone mufflers from Cone Engineering might actually work well, 1 3/4" inlet and use a graphite gasket in between the header and the muffler to take up the gap, you'd have to use a clamp and fab up a bracket for the mufflers. Think that would look and sound cool and be much more free flowing than the stock muffler, alternatively 18" quiet core muffler would work well too.
 

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this is essentially what I did with mine as well.

 

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Discussion Starter · #6 ·
That’s yours!? I’ve seem photos of that bike before... I love that bike. It is BADASS.

Do you have a YouTube sound clip by any chance??

Do you remember which jet sizes you used to tune the carbs to those mufflers?
 

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I didn't have to rejet at all. I did make some baffles for those pipes though.

Here's a vid of it idling

 

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Discussion Starter · #8 ·
Love it.

How did you make the baffles?

I was thinking of just inserting a perforated tube into the pipes and the drilling holes at the tips of the pipes, and sticking a vertical bolt through to keep the baffles in.
 
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