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Author Topic: Mac 4-1, Did YOU have to rejet?  (Read 5045 times)

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Offline ddanz27

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Mac 4-1, Did YOU have to rejet?
« on: April 13, 2011, 12:59:27 PM »
Mac says there is not a need to rejet. Is this true or no.
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Offline TwoTired

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #1 on: April 13, 2011, 01:05:17 PM »
True, unless you have the a "lean burn" 77-78 model SOHC4 with PD carbs.

(Applies to exhaust change ONLY, if other changes are made to induction or engine, that is another matter.)

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

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Offline ddanz27

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #2 on: April 13, 2011, 01:18:14 PM »
Thanks TT, on the same lines... Where might I find good quality header gaskets? I cant find any out there. Other bikes yes but for the 350f I am striking out right now :(
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Offline TwoTired

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #3 on: April 13, 2011, 01:27:19 PM »
Have you tried Western Hills Honda?
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline benjamin550

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #4 on: April 13, 2011, 03:04:11 PM »
I bought my Mac pipes at www.nichecycle.com/. WAY cheaper than actually ordering from Mac (no clue why), free shipping,  and I also bought gaskets from them. They were really helpful on the phone too.
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Offline ddanz27

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #5 on: April 13, 2011, 05:45:59 PM »
Quote from: rotortiller on April 13, 2011, 04:17:02 PM
I stuck one on my K-7 this year and it needed no rejet (115 mains). It runs smooth with nicely tanned spark plugs PD41A carbs. I'm running the stock airbox with a filter and the float levels are stock at 12.5mm. It's pretty quiet.

RT
Are you saying they are quieter than stock? Thats not really what im looking for tone wise...
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Offline Hasenkopf

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #6 on: April 13, 2011, 07:20:52 PM »
you can pull the muffler apart and do things like drill little holes in the baffle.
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Offline pikehk

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #7 on: April 13, 2011, 07:44:38 PM »
Word of Caution: Niche Cycles does not have exhaust gaskets for CB500 four. Trust me the ones on the website are for the twin. My Mac Exhaust is pretty dang loud. How loud do you guys think your bike should be? My Mac is louder than most after market exhaust for newer bikes.
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Offline cb650PK

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #8 on: April 13, 2011, 08:17:22 PM »
Mac has street baffle and race baffle and they can be bought on there web site I think. Obviously the race baffle which is strait threw design is louder then the chamber street design.
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Offline TwoTired

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #9 on: April 13, 2011, 09:50:02 PM »
I would expect the "race baffle" to require a some carb alterations to restore proper mixtures throughout the operating ranges.
No direct experience, though.  Just and expectation on based on physics, how the engines works, and what the carbs were originally intended to provide.

Cheers,
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Lloyd... (SOHC4 #11 Original Mail List)
72 500, 74 550, 75 550K, 75 550F, 76 550F, 77 550F X2, 78 550K, 77 750F X2, 78 750F, 79CX500, 85 700SC, GL1100

Those that learn from history are doomed to repeat it by those that don't learn from history.

Offline Scott S

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #10 on: April 14, 2011, 05:11:34 AM »
 CB500, Mac 4-1, Uni-Filter in stock airbox, Pamco Ignition....no need to re-jet.

 I like the sound of the MAC with the baffle. It sounds "growly" and mean up close, but when my GF or Dad does a drive-by for me, I think it's actually pretty quiet. That means your neighbors probably won't hate you. Not because of your bike, anyway.
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Offline mrrch

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #11 on: April 14, 2011, 05:39:18 AM »
There is no packing in the all black unit, just baffles, I drilled my new one last year for a bit more rumble.
+1 on ordering from Niche Cycle (also abit cheaper direct thru their website rather than their ebay listings)
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Offline Scott S

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #12 on: April 14, 2011, 05:42:01 AM »
 I have the all black unit, too. Bought it more for looks than the price. I prefer the all-black on my bike.

 There's a difference in the packing/baffling on the chrome vs. black units?
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Offline ddanz27

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #13 on: April 14, 2011, 06:18:26 AM »
Quote from: pikehk on April 13, 2011, 07:44:38 PM
Word of Caution: Niche Cycles does not have exhaust gaskets for CB500 four. Trust me the ones on the website are for the twin. My Mac Exhaust is pretty dang loud. How loud do you guys think your bike should be? My Mac is louder than most after market exhaust for newer bikes.

I only mention the volume because Rotortiller mentioned that his is quieter than stock. Thats definitly not the direction I wanted to go. I have always had the belief that a loud bike is a safer bike (because they can hear you AND see you). Just my opinion though. I am not wanting a bike that rattles your mirrors when it drives by but something that sounds good and will be noticed is all.

Thanks for all the guidance on the Macs guys. From what I have seen out there, there is not another 4-1 that is the same value is there? I am wanting black and will be wrapping anyways so chrome is something I am staying away from.
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Offline apex_seeking

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #14 on: April 14, 2011, 06:49:00 AM »
I had the factory 4-4 on my 550. I swapped it out for the black mac 4-1. Stock air box and stock jets. Runs great with the baffle and should be rejetted to run without.

As far as being loud, it is louder than stock with the baffle and I think it sounds good. Without the baffle, it's really loud. I count say how loud it is for onlookers but when on the bike it's too loud to be comfortable.

just my .02.
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Offline Radam

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #15 on: April 14, 2011, 07:10:36 AM »
I have the mac 4-1 on my F3. It rattles a little bit sometimes, so I was wondering if replacing the baffle would fix that? I've made sure that it's tight everywhere else. I'm not sure if mine is drilled or not because it came that way. I think it is drilled. If I get a replacement baffle should I go ahead and drill it before I put it in?
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Offline apex_seeking

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #16 on: April 14, 2011, 07:45:17 AM »
Mie had a nasty rattle even after I got the set screw tight, It was the interior end of the baffle. It didn't fit tight so I welded a screw to that end and put a bolt in there to hold bothends tight. Now its not as tinny. Little more of a growl.
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Offline lone*X

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #17 on: April 14, 2011, 08:22:19 AM »
To be louder your pipes need to be more open that stock, like straight through, then Yes, you would need to re-jet.  But there is more.

"I have always had the belief that a loud bike is a safer bike (because they can hear you AND see you)"

This line needs to be thoroughly diagnosed.  IMHO The loudest a pipe will be is from behind or to the immediate side.  Even straight pipes are not as loud from the front of the bike.  So for someone else to hear them in full glory they would need to be behind or beside you.  This is not from where most of the road dangers come from.  By far the most common danger is from a cage making a left turn in front of you.  For this you need a really loud horn.  Check out Stebel motorcycle horns, Sounds like a 18 wheeler, loud when you need it and its loud all the way around.  It will make people drop their cell phones, wet their pants, and take notice! And it is only loud when you need it.

Also, is a loud bike really safer if it is in fact destroying the riders hearing?  Other people harming you is one thing, but harming yourself?  This is not just an opinion.  It is fact.  One that I can attest to.  You may be riding your bike regularly, hours on end, and the combination of loud pipes and wind noise can greatly affect your hearing.  It is a slow progression to hearing loss, you will not notice it for several, maybe many years, but it will be there.  After more that 40 years on bikes I truly wish I had left the baffles in all the pipes on all the bikes I have owned.  It really sucks to be half deaf.
« Last Edit: April 14, 2011, 08:24:36 AM by lone*X »
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Lone*X  ( Don )

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VTX1800C for two up cruisin.
Several others have come and gone but whose keeping track.
52 years on two wheels and counting.....
"The best safety feature of any motorcycle is the one God put between your ears.  It's also the least utilized"

Offline ddanz27

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #18 on: April 14, 2011, 08:26:26 AM »
You bring up some really good points loneX. Thanks for your input. That all makes sense. I will check those horns out too. Are they gaudy at all? I need to replace my horn anyways but want something subtle and black...
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Offline lone*X

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #19 on: April 14, 2011, 08:33:43 AM »
They aren't really gaudy, not like air horns with trumpets, although they do have a little bulk.  I haven't put one on my 550 but have had several on other bikes, including my daily driver, an 1800VTX.   If you have a Harbor Freight store around you they sell a chinese clone of the Stebel that you could look at and decide if it would work for you.
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Lone*X  ( Don )

75 CB550K1  
VTX1800C for two up cruisin.
Several others have come and gone but whose keeping track.
52 years on two wheels and counting.....
"The best safety feature of any motorcycle is the one God put between your ears.  It's also the least utilized"

Offline mrrch

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Re: Mac 4-1, Did YOU have to rejet?
« Reply #20 on: April 14, 2011, 09:10:50 AM »
I added a second baffle retaining screw 180 degrees from the original to stop the tinny rattle.
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