Topic: Is Mac exhaust a bolt-on?1978

[alis]

Purchasing an exhaust for a 78 750k, Mac says that their exhaust is a direct bolt on and that there is no need for any additional parts (hangers, brackets, etc...) so all you receive is just the pipes. Anyone out there or in here ordered the exhaust recently?  What came with it?
Thanks,

[fergie]

I put a mac on my 78 550k . as far as I can remember it came with a clamp to conect the front and rear pipe parts together,a hanger for the rear half of the pipe and a bracket to stop the center stand from hitting the chain. no jetting required. bike ran perfect just bolting it on. a 750 might run differently though. its always a good idea to do a plug chop after installing a different pipe or air filter system.

[mick750F]

   You don't say which system you're buying but I put a MAC 4 into 1 on my '78 750F a few years ago. It was a direct bolt-on...the F bikes come with a 4 into 1...except for the fact that it was an incredible wrestling match between me, the header and the bike to get the damned thing installed. I posted a rant post about it at the time and the consensus was that sometimes they pop right on...sometimes you just want to take them and bash them against the ground. Guess which one I got.   

   If you are buying a 4 into1 and you have an F it should have everything you need. I'm not sure if a 4 into 1 on a K needs anything more than comes with it. You might have to rig up a stop for the center stand. I have no idea about the fitment of one of their 4 into 2 sysytems.

Mike 

[XN]

The bracket for the center stand stop wasn't even close to working. Other than that they fit fine.

[sangyo soichiro]

I got one for my '74 and '72 CB 750s.  These two bikes have the older 'spigot-type' manifold clamp thingy (as opposed to the way they mount on later models).  Anyway, when I bought the '74, it came with the 4-1 but it wasn't mounted.  When I got the bike home, I figured I'd slap on the exhaust and see how she runs.  "Oh poop... it looks like that Mac exhaust is for the later models.  No wonder it wasn't mounted...."  So I jerry-rigged it up so I could at least start her up.  Then I thought, hey... it doesn't fit that bad.  Shame to waste a good exhaust...

I started to like the sound better than my loud-ass makeshift drag pipes on my cafe, so I bought a 4-1 for that bike.  I made sure I ordered the one for that year of bike (supposed to have the spigot-mount).  But the exhaust came and it was just like the other one!  What the hell...?  Hard to believe two different people (me and the guy I bought the '74 from), ordering Mac exhausts from two different places (I used CycleRecycle, he used ebay) could both screw up on getting the right exhaust.

Not sure if there's a mistake on Mac's side of these deals, but I swear the exhausts I have aren't for the years of my bikes.   

[MCRider]

I got one for my '74 and '72 CB 750s.  These two bikes have the older 'spigot-type' manifold clamp thingy (as opposed to the way they mount on later models).  Anyway, when I bought the '74, it came with the 4-1 but it wasn't mounted.  When I got the bike home, I figured I'd slap on the exhaust and see how she runs.  "Oh poop... it looks like that Mac exhaust is for the later models.  No wonder it wasn't mounted...."  So I jerry-rigged it up so I could at least start her up.  Then I thought, hey... it doesn't fit that bad.  Shame to waste a good exhaust...

I started to like the sound better than my loud-ass makeshift drag pipes on my cafe, so I bought a 4-1 for that bike.  I made sure I ordered the one for that year of bike (supposed to have the spigot-mount).  But the exhaust came and it was just like the other one!  What the hell...?  Hard to believe two different people (me and the guy I bought the '74 from), ordering Mac exhausts from two different places (I used CycleRecycle, he used ebay) could both screw up on getting the right exhaust.

Not sure if there's a mistake on Mac's side of these deals, but I swear the exhausts I have aren't for the years of my bikes.   

Rob at Cycle Recycle II certainly knows better, he is a CB750 genius. He could have made an honest mistake but I doubt it.

More likely, many 4-1 pipes assume the owner will convert the mounts. The spigots come off, and the pipe bolts directly to the head with bolts supplied. New exhaust gaskets are required (be sure to pick the old ones out, they were between the spigots and the head, smashed flat.)

This is true with Kerker and others. Could be the answer. Or I could be wrong.

[alis]

Sorry for not clarifying, its going to be a 4 into 1 for a completely stock 78 750k.
Thanks for all you information.
Next question? Am i better off ordering directly from Mac or from another site, I was going to use BikeBandit.com, they have it for $260 in all black. Are the ones deirctly from Mac better built?

[MCRider]

Sorry for not clarifying, its going to be a 4 into 1 for a completely stock 78 750k.
Thanks for all you information.
Next question? Am i better off ordering directly from Mac or from another site, I was going to use BikeBandit.com, they have it for $260 in all black. Are the ones deirctly from Mac better built?

No problem, sorry I couldn't help. As far as ordering, I don't know.

I'm going to CRC2 this weekend, assuming they don't have a waiting line out the door, I'll ask. Exactly what part of yours doesn't fit. I was thinking the muffler mount on a 78K is different than on earlier Ks.

They've been selling MACs for at least 20 years.

[sangyo soichiro]

Thanks MCRider.  I was able to mount them... just confused as to why they didn't utilize the old spigots. 

[MCRider]

Thanks MCRider.  I was able to mount them... just confused as to why they didn't utilize the old spigots. 

Oh, OK. Yeah the spigots are throw aways...usually.

The Marshall Deeptone I bought for my project requires the spigots. I had already disposed of mine as I'd been running a MAC then a KERKER, then an RB Racing all of which didn't use them.

I had to scramble, a member here had some spigots.

[alis]

Sorry for not clarifying, its going to be a 4 into 1 for a completely stock 78 750k.
Thanks for all you information.
Next question? Am i better off ordering directly from Mac or from another site, I was going to use BikeBandit.com, they have it for $260 in all black. Are the ones deirctly from Mac better built?

No problem, sorry I couldn't help. As far as ordering, I don't know.

I'm going to CRC2 this weekend, assuming they don't have a waiting line out the door, I'll ask. Exactly what part of yours doesn't fit. I was thinking the muffler mount on a 78K is different than on earlier Ks.

They've been selling MACs for at least 20 years.




I haven't even bought anything yet, Im not into welding so i really want an exhaust that can bolt right on.  To me simple is sometimes better.  If you could let me know what you find out I would apprecitate it.

[MotoMartin]

MACs aren't a real high quality product. I had a 4 -1 set on my XS1100, then another set of MAC pipes this time 4-2.  The head pipes can get rusty in as little as 3 months. The chrome is pretty thin, and they will go blue almost instantly. It may be worth the extra $ for a higher quality product or a used set of OEM. Just my 2 cents.

[GammaFlat]

There's really no welding required. 

The 77/78 bikes were outfitted with 2 studs per cylinder.  The exhaust end that meets the head is flanged.  2 odd looking parts and a "flower" with 2 holes in it complete the installation.  The flower presses the two "half round retainers" into the pipe flange and subsequently into the gasket/head once you tighten the nut on the stud:


The pre-77 has a spigot  held onto the head with 2 screws.  The pipes then slide over the spigot and a flower "clamp" tightens the pipe to the spigot. 

A Mac comes with some "header bolts" (socket head bolts) and the pipes have a retainer with holes (see pic):


The bottom line is that the head is the same and the exhausts are interchangeable.  The tricky part is making sure you have the correct parts and also not messing up the threads in your head if you need to remove studs. 

[alis]

Ok, thanks, so my unerstanding now is that the exhausts are interchangable.  Does the ones for 77 or 78s come with a different way of holding up the muffler than the earlier models?

[GammaFlat]

The K6 and prior factory exhausts hang from the footpeg bolt.  The 77/78 are attached to a plate that attaches to the frame near the footpeg.  The K7/K8 footpeg is placed slightly in front of where the k6 and prior footpeg goes (maybe higher too?!). 

In any case, the footpeg is what you care about for a MAC and most aftermarket exhausts.  I'm about to move a MAC 4-1 from a K6 to a K7.  I believe the existing hanger (came with the MAC) on the footpeg will work for either. 

[alis]

Thanks Gammaflat for the information.