Topic: Mac 4-1 header

[Tugboat]

I got lucky and picked up a new, never used Mac 4-1 header for my CB750 at Barber for $50. Any tips on installing these? My stock 4-1s aren't terrible but they're not great either. I'm already running a Mac muffler.

edit: My '76 F has a '77 K motor, if that matters...

[calj737]

1. New exhaust gaskets
2. AntiSieze on studs when you reinstall
3. Fitment is tricky, take your time and have plenty of 4-letter words on hand
4. Finish on those headers is poor, will likely show poorly after a full season riding. But for the $ you paid, hard to complain about that.

[bjbuchanan]

Depending on the exhaust style on your 750 you might not need gaskets. Do you have spigot style or the flange clamp style and also does your new exhaust match?

Finish is poor like said but,well, too bad? Lol

Fit goes right on if you clean up the spigots if you have that style. The clamps and flanges are a pain, I can't stand them

[seanbarney41]

For a MAC, you will remove the spigots, I don't know if your 77k has them or not, and you will need new copper exhaust gaskets.  As mentioned above, if your MAC is painted and not chrome, the paint is shot after one season or 50 miles in the rain, whichever comes first.  MAC has a couple different baffles available, standard street baffle sounds like someone blowing their nose, race baffle sounds great but may be too loud for some...

[Tugboat]

Yeah, my bike has the half-moons and the clamps. The header is chrome so hopefully it'll hold up a little better than the painted ones.

[Old Scrambler]

Your stole it.................recommend you get a helper to SPREAD the pipes to fit upon install and minimize paint damage to the frame.  Also advise regular applications of WD40 or other protectents at the 4-1 juncture to help keep it clean and prevent rust.

[socal1200r]

Since you only spent $50 for the pipe, I'd spend the money and get it ceramic-coated.  When I got my CB650 a couple of months ago, it had a chrome 4-1 header, but not a MAC.  'Course some of the downpipes were discolored, with the outer pipes being more blued than the inner pipes.  I removed it and got it ceramic-coated satin black ($180), and I'm happy so far with the result (150 miles).  I only had two color choices, satin black or silver, so I went with the black.  And I second the tip to use anti-seize on those threads.     

[calj737]

Ceramic coating is a great idea. But, if you prefer the "chrome" just treat the interior. That's where it matters anyway for performance and corrosion resistance. The exterior you can tend to with diligent wiping or WD-40 as you see fit.

[socal1200r]

Ceramic coating is a great idea. But, if you prefer the "chrome" just treat the interior. That's where it matters anyway for performance and corrosion resistance. The exterior you can tend to with diligent wiping or WD-40 as you see fit.

'Course a main advantage of a chrome exhaust is it will tell you which cylinders are running lean.  I'm not a big fan of chrome, just more things to wipe down and keep shiny.  That's why I bought another set of engine cases and case guards, and dropped them off to get them powder-coated gloss black.  No more polishing aluminum for me, lol...

[Tugboat]

Should I expect to have an issue with my center stand hitting it?

[flybox1]

Should I expect to have an issue with my center stand hitting it?

just roll it off the stand slowly, and see where it lands.  you may need to fashion a stop to keep your stand off the chain.

[mono]

MAC provides a little piece that bolts on to act as a stop.  You can easily fab one out of a strip of 16ga steel if you need one.

[evanphi]

My stand stop (now it is on the other side):

[Tugboat]

Is that bolted onto the passenger peg?

[Mo]

My stand stop (now it is on the other side):

Also, is that the cone eng quiet core?

[evanphi]

Is that bolted onto the passenger peg?

Yes. Better pic, taken today...

My stand stop (now it is on the other side):

Also, is that the cone eng quiet core?

Yes