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Old, Bold rider
2002 Honda 919, 1976 Yamaha XT500 cafe, TC-JAG TZ250
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2,488 Posts
Discussion Starter · #1 ·
Anyone out there have a stock header laying around for any year 919? I need a measurement of the inside diameter of the header pipes at the exhaust port preferably with calipers or snap gauge and micrometer.

I've been studying high temperature acoustic wave theory for a while now, and am designing an exhaust system consisting of four individual megaphone / baffle assemblies with a continuous exponential taper from the exhaust ports to the reverse cone termination. What happens at that end is part and parcel of the entire package: the completely mechanical baffle assemblies (yeah, no glass packs). Obviously I am keeping the specifics close to the vest, and am provisionally calling it Thar EERS (Exhaust Energy Recovery System). From my initial designs it looks like the total weight of the system will be eighteen to twenty pounds made of 316 stainless.

Then there's actually making all four fit to the bike. The only way I can figure is hydroforming, at least for prototypes.
No instant gratification here. It's going to be a long process.

Rob
 

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McTavish
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6,491 Posts
Rob,
If I had a spare header I'd stop everything I was doing and get a measurement for you!
I absolutely love the sound of a tuned pipe per cylinder!
 

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I WANNA RIDE!
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1,486 Posts
Is this what you want?
Either I'm doing something wrong or Honda is inconsistent (which I think it's me not Honda) because I get 4 different readings.
Anyway, here's what I got in inches..
Automotive tire Automotive wheel system Gas Engineering Rim
Calipers Wood Finger Audio equipment Measuring instrument
Calipers Wood Measuring instrument Gauge Satellite phone
Calipers Automotive tire Finger Bicycle part Gadget
Automotive tire Portable communications device Line Audio equipment Communication Device
 

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Old, Bold rider
2002 Honda 919, 1976 Yamaha XT500 cafe, TC-JAG TZ250
Joined
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2,488 Posts
Discussion Starter · #4 ·
Is this what you want?
Either I'm doing something wrong or Honda is inconsistent (which I think it's me not Honda) because I get 4 different readings.
That will do nicely. Thank you.
A quick CAD draft of one of four pipes with arbitrary bends:
Bicycle part Auto part Automotive exterior Font Pipe


Just getting the lay of the land, as it were. The problem is laying it out for proper fit on the bike, but it occurred to me that a laser cutter / engraver could be used to produce 1/8th inch thick hardwood discs corresponding to the constantly changing diameters about every half inch separated by appropriately radiused distance pieces with a cable threaded through tying it all together. In that way it should be relatively simple to get the profile right and have patterns that could be used to produce bucks to shape the pipes. I hope!

More to come
 
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