Topic: 750k stock 4-4 or 4 -1 exhaust? I'm curious, was this a fad in the day?

[dylboss]

I'm curious.  I see so many "original" bikes that have been outfitted with a 4 -1 exhaust, or even a 4-2 exhaust.  Was this a fad in the day, or does this continue?  I'm kind of a stock guy myself, and I LOVE the look of the 4-4 exhaust, so I don't really get it.  What do you think?

[killersoundz]

I personally love the sound of a 4 into 1 on a cb750. That makes it for me. It just doesn't sound like anything else. Also slightly increased performance. That's my case

[CBNJ74]

I'd love a stocker for my K3 but decent used ones are hard to come by And new ones go for around 1200 bucks!

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[Stev-o]

It was a fad back in the day. Many hoped for increased performance but it took more than just slapping on a new pipe. 
Nowadays, an original 4-4 in great cond is hard to come by, and expensive if you do ($1000).
On the other hand, a new 4-1 can be bought new for a little over $400.

[d3buttz]

Supposedly 4-1 are easier to to tune / balance carbs and have a better tourqe range on the bottom revs, but all that was most Likely stuff they said to convince people to buy them. I hate the unsymmetrical look of 4-1's

Brought to you by Carl's jr.

[dylboss]

Ok, interesting so far.  I'm kind of a purist, so spending 1k on a set of new pipes to keep it original is ok in my book for a restore, but I do understand the budget side of things, 'cause I certainly ain't rich.  A rider.....well, ok....then a 4-1 makes sense.  I guess I'm a little anal with keeping things OEM and true to their original state.

[killersoundz]

This video helps explain why I like the sound so much

CB 750 Cafe Kerker 4-1 (no baffle)

[shinyribs]

I love my 4-1! It is not symmetrical and I dig that. I love how there is one side of the bike that is completely free of exhaust tubing! Exhaust on these bikes are impossible to hide completely and I hate to see them. And I think a 4-1 just sounds great. My 4-1 sounds nothing like that video of the green bike. I dont have the megaphone on mine.Personally ,I think they sound like they are under water at idle with that setup.

I have all the respect in the world for the stock 4-4. It was the original setup and looks cool in a retro sort of way,just not my cup of tea.My bike had 4-2 chopper pipes when I first got it. The had a nice deep sound at idle,but these bikes always sound zingy when you whack in to the throttle.You just can't hide the sound of an inline 4.

Like I said,i did everything I could to hide my exhaust. I think it makes the bike just look bulky.When sitting on blacktop the pipes basically disappear.

PART_1332634066690 by Shiny Ribs, on Flickr

[Hinomaru]

It was a little more than a fad back in the day, especially with the street/strip crowd who rode their bikes to the drag strip on Saturday night. A stock Honda HM300 exhaust system was heavy at around 30 lbs. and slowed you down in the 1/4 mile. Aftermarket 4 into 1 exhaust was a popular weight reduction/performance mod as it changed your power-to-weight ratio. The lightweight RC engineering header is a good example:
 

[cgswss]

I guessing you already know that there are 4 into 1s that are for show and 4 ->1s for performance.  In general, to get performance you have to have some spaghetti in the pipes to get equal length pipes.  4->1s that have nice neat side by side pipes are more for looks.  A TUNED 4->1 with the proper jet and needle changes will often give you about a 10% power increase and a lot more noise.

[phil71]

Who knows what was behind the design, but hm300s sound sick and look threatening.

[754]

 Easier to clean, and as mentioned lighter..  and sound.. and you can go to straight thru in 2 minutes..
 Gotta remember back in the day, after masking a few hundred thousand 4-4s, they got a tad boring.. they sounded good but it got boring after hearing iot a thousand times.... if you were there, you would totally understand..

[phil71]

Everything old is new again. Anytime I rolled up on some sportbike , they were always shocked at the hm300 note.

[xsmooth69x]

It was a little more than a fad back in the day, especially with the street/strip crowd who rode their bikes to the drag strip on Saturday night. A stock Honda HM300 exhaust system was heavy at around 30 lbs. and slowed you down in the 1/4 mile. Aftermarket 4 into 1 exhaust was a popular weight reduction/performance mod as it changed your power-to-weight ratio. The lightweight RC engineering header is a good example:
 

the cigar in his mouth just makes him look like a boss. i would buy that exhaust because of it!

[TwoTired]

I'm curious.  I see so many "original" bikes that have been outfitted with a 4 -1 exhaust, or even a 4-2 exhaust.  Was this a fad in the day, or does this continue?  I'm kind of a stock guy myself, and I LOVE the look of the 4-4 exhaust, so I don't really get it.  What do you think?

4 pipes/mufflers are heavier than 2 or 1.  And aftermarket was cheaper than buying through Honda.

A properly tuned 4 into 1 can give an HP boost at a calculated RPM.  The race bikes had tuned 4 into 1s (tuned), and of course there's a lot of popularity in having your bike "look" like a race bike, that "fad" was there from the beginning.  And, much of the changes were for the sake of "personalization".  It cheap to make a bike look like it is custom.  And, few will know if the performance envelope got better, worse, or simply "changed".

4 into 1s are a trade off, though.  If tuned so that the reflective exhaust pulses arrive at the exhaust port just as the valve is closing, this only happens in a narrow RPM range.  At all other RPM's the reflected pulses just foul the exhaust extraction of neighbor cylinders and actually hinders power output.  Doesn't matter with race bikes at full constant flog.  But, a tuned 4 into 1 on a street bike, is mostly operated in the RPM range where the exhaust is a detriment to cruise power.

Cheers,

[CoachDoc]

I'm curious.  I see so many "original" bikes that have been outfitted with a 4 -1 exhaust, or even a 4-2 exhaust.  Was this a fad in the day, or does this continue?  I'm kind of a stock guy myself, and I LOVE the look of the 4-4 exhaust, so I don't really get it.  What do you think?

I agree totally about the 4-4 pipes.... Love 'em. My original pipes on my '74 550 rusted out by the early 90's. When I sought replacement 4-4's from mother Honda, they were no longer available. Flash forward 17 years , and amazingly to me Honda made another run of OEM 4-4 pipes, and I jumped at the opportunity to get a set. In the interim I ran briefly a very nice Mac 4-1, which now adorns Frosty's 550 down under. Both systems are Good looking, and a lot of guys like the look or the lighter weight of the 4-1. Me, I'm content to have a good looking OEM 4-4 system once again.

[cgswss]

Back in the day, I had a very long drill bit with a reduced shank so I could use it in a 1/2 drill.  That drill when up the rears of many "stock" mufflers.  I had race bikes to tune, I just wanted more sound on the street bikes.  Most of my street bikes were "almost" box stock.  Only once did I build a Q-ship.  That was very breathed upon suzy 1100 (well real displacement was much more then that)  On that bike I gutted the stock mufflers.  With about everything after market inside, of course I re-jetted and made some other changes.

I used to joke that it benefited from "trickle down tuneing"  When I found something that worked better on my race motor, the old part from the race motor would find it way into my Q-ship.  The only thing that gave it away to the trained eye was how low it sat in the front and how stiff the rear was.  That and maybe the lack of tread on the rear tire.  That was at about the end of the "good old days" on Woodward.  But we had other places we went to race.

[754]

 I got up to as high as 58? mpg with a Hooker 4-1 and pods..it was actually 67mpg using an Imperial gallon. If it suffered at any rpm range it would be down low, certainly not at cruising speed or higher.. If they had as LMITED A POWERBAND as some are suggesting, they simply would not have sold in huge numbers..
 Look around today.. what is one of the first/popular mods done to any bike these days.. somethings dont change much.
 Keep in mind, there was a large gap of a few decades between the throwing the stock pipes away days, and when the finally started producing them again.

[cavi]

I just bought a 78 cb750f and I have the stock 4 in to 1 but my muffler is rusted and a bit too quiet.  i would ultimitly like the kerkler, but I am considering just the mac slip on muffler for now.  Has anyone used one, do they sound okay or bad?   If I go with the kerkler am I going to have to rejet or just to tune the carbs?
I am also open to other suggestions

[Bailgang]

The main reason I picked a vintage Japanese 4 cyl bike in the first place rather than a V-twin cruiser is because that's what I remember the most when I was a kid growing up in the southwest suburbs of Chicago along with those bikes running aftermarket 4 into 1 exhausts (usually Kerkers) and I've grown to prefer the look of the 4 into 1 over the stock look as well. I shy away from the debate of whether there is any improvement in performance because for me it's nothing more than personal preference besides the cost of a NOS or repro exhaust was way out of my budget though I must admit that the Kerker that's on my kids 750 is a bit too loud and obnoxious for me.

I have a nephew that has the Kaw H2 my brother used to ride at that time and it still has the Bill Wirges expansion chambers on it that my brother put on it many moons ago.

[Don R]

Even if you ran your stock exhaust they rusted out soon. In the midwest they might only last a couple years. Then a 4 into 1 was a no brainer. Our Honda shop took truck loads of stock exhaust to the scrapyard.

[BossMaroon]

My exhaust rusted after just 1 or 2 years after I bought my 750 in 1974.  Never even considered buying replacements, went with a Kerker, never had to retune, and I thought at the time it sounded better and was a bit faster.  I would have to say most were changed due to rust.  On my 1974 replacement that I have now, having all stock exhaust seems like the right way to go, I bought 2 used and 1 new when replacing the old rusted exhaust that came with the bike.

[lucky]

Its all about the BARK!!!

CLICK on the photo for larger version.

[shorty24]

From what I understand concerning the Honda engineers' stand on placing 4-1 exhaust on the F model fours was not so much about (engine) performance as it was weight loss.  Stock 4 into 4's with individual muffler/silencer setups was HEAVY.  IIRC, a little over 20lbs was lost just going to a 4-1.

[Stev-o]

I just bought a 78 cb750f and I have the stock 4 in to 1 but my muffler is rusted and a bit too quiet.  i would ultimitly like the kerkler, but I am considering just the mac slip on muffler for now.  Has anyone used one, do they sound okay or bad?   

My 550F had a slip on Mac on it when I bought it. I did not like the sound or look and sold it. Found a good cond stock and put that on.