Topic: hand built performance header for cb750

[Blackandsilver]

so i think im gonna have a crack a building a header for my 750. thinking 4into 2into 1 does anyone have any input on pipe diameters lenths and radii?
should i just try to copy a yosh? or is there more modern thinking that could be used to get a better performing header?
i really like..is it hans'?... idea of the cbr600 going onto the cb500 downpipes but id like to do it all out of stainless.

[zouev]

The exhaust topic got really complicated really fast for me. You will have the perfect PWM only at a certain range if done right. You must take in to consideration you intake characteristics as well. I am really new to the topic but do A LOT of reading before I build my bike.

There is software that will allow you to do all the number crunching by entering your engine spec. A lot of numbers but it seems to be fairly accurate. I am speaking of Engine Analyzer Pro.

Some links:
http://users.erols.com/srweiss/index.html

AND:
http://books.google.ca/books?id=RYsglAO9f8gC&pg=PA128&lpg=PA128&dq=engine+pulse+width+of+the+pressure+drop&source=bl&ots=bU7Is-dMep&sig=zZ-MTt4owZ56Puj0sJJjfOIaLRw&hl=en&ei=lLHPTtKcLaXn0QGfxdwr&sa=X&oi=book_result&ct=result&redir_esc=y#v=onepage&q=engine%20pulse%20width%20of%20the%20pressure%20drop&f=true

Chapter 12 pg116 and on

I think it is cheaper to buy, but what guarantees that they didn't guess?

I hope this helps.

[mickey6]

I'm not much help in this department.... but I'm curious as to which direction you take it.
I'm following this one to learn .

[754]

I was running a turbo headpipe 4-1, left exit flange above dyno cover pipe leads toward rear top engine bolt then angles down into a large megaphone.
 I did it for ground clearance, was able to saw off sidestand mount and lower bike at least 3 inches if not more.  Because it was a turbo header (unequal length BTW) it has small headpipes, I think to increase velocity.... what ,I noticed is the bike felt very torquey... probably ,mostly due to Weber carbs.
 Just mentioning it as smaller pipes are a bit easier to build with, fit tighter spaces, may get a cleaner look. The header was all built of mandrel sections welded together.
 I am thinking that the small diameter helped midrange, if that is fact, it probably lost a bit at the topend, but I will say this, very nice midrange and a loit of fun to ride.. FWIW..

[seanbarney41]

I think it's in The Thoughts of Hondaman section on here somewhere...where he talks about dyno testing aftermarket 4 into 1's...basically everything available at the time (1970's) was within a few hp, with the Yoshi pipe at the top.  If I were you, I would concentrate on getting the headpipe diameter and length correct, this needs to be designed to enhance the power curve of your engine...unfortunately, the correct length and diameter doesn't necessarily fit the chassis conveniently...also concentrate on designing the collector/s, try googling merge collector...you got a lot of research to do, then a lot of experimentation and work...lotsa guys just figure on using a pipe that can be jetted right with good ground clearance and less weight than stock and call it good...

[BLUE71TURBO]

 Basically it all boils down to what kind of power band you want and what style of riding.  Just putting around
 on the street,  road racing as in carving up the long winding roads or mountains, or drag racing.  Also alot depends on what type of fuel management, carbs, fuel injection, and turbocharging. Oh and camshaft profiles.
    You need to look at the new bikes and old,  road racind and dragbikes.  There's alot to consider when designing the best performance header exhaust system.      Pipe diameter, length, design of the collector and the lenght and cone shape of the megaphone ( with the silencer )   

[Don R]

I recently aquired a 77F stock header, It is a tri wye design. in the stamped section the four pipes merge into two then two into one. Like the best drag race headers, there is little straight pipe,  it's mostly long radius turns. I would assume it is the best design honda came up with since it's different than the 76F pipe and the last model . The 77 collector is reduced to 2" from 2 1/2".

[Retro Rocket]

Some inspiration for you....

[mick7504]

Whilst on the Titanium thing 

[Retro Rocket]

Thats a nice pipe Mick....

[mick7504]

Thats a nice pipe Mick....

Thanks mate, it's a beauty and I had some explaining to do when someone saw the bank statement. 
12 visits to the womans hair & beauty salon = 1 Ti exhaust system.
That was my reasoning and it got the point across. 

[Retro Rocket]

Thats a nice pipe Mick....

Thanks mate, it's a beauty and I had some explaining to do when someone saw the bank statement. 
12 visits to the womans hair & beauty salon = 1 Ti exhaust system.
That was my reasoning and it got the point across. 

Yep, its like the old saying, "if you can't dazzle them with brilliance, baffle them with bull#$%*"   

[BLUE71TURBO]

Some inspiration for you....

   That is just cycle porn for me !       I'm gonna build a turbo'ed  1978- 1980 kz1000 LTD  About 1300cc's
      That is a great header design.  I really dig that tapered merge collector.  That design is exactly what i
     was talking about when compared to that old Yoshi design header collector.