4 to 1 Exhaust... what's the truth?

[BigDaddyD]

Hey all...

So once and for all...
What's the truth behind going to a 4-1 exhaust?
I've been reading alot of back and forth here about no real gains besides some weight loss.
And then I've heard people swear by them.
So what's the story?

I've got a '77 gs750 w/pods that's running fairly well. But my 4-2 exhaust is in fair condition tho a little beat up here and there (some leaks and missing a head gasket bolt, baffles starting to rust a little).
I'm just thinkin if there's a significant power gain, that when I go to fix my exhaust issues I might just step it up to a 4-1 and sell my old setup since I already have the pods on there and she's running smooth.

So what's the deal?
Are they worth it?
Are there reasonable gains for the money or should I just fix up the system I have now??

Help me see thru the lies and deceptions!
;-)

Thanks!

 

[Nessism]

I'd love to see some actual dyno numbers to quantify how much power gain can be achieved by adding pods and a header. Proponents talk in terms of significant increases but in my experience the gain is more in the slight to moderate range.

My estimation is a power gain in the range of 6%, mostly at high rpm. Power may actually go down at low/mid rpm depending on the pipe. Noise will go up, maybe significantly, again depending on the pipe. Pods add a significant amount of intake snort noise. Weight will come down - which boosts performance.

On a more personal side, it seems that a large number of headers on GS bikes I've seen are rusty and loud. Many also require elimination of the center stand and block the oil filter. V&H seems to be the best commonly available (in the US anyway) - MAC is the only other. Used pipes show up on ebay but are often dented, since they typically hang low under the engine, and rusting.

I've been looking on ebay for more than a year now for a nice clean stock exhaust for my 550E - no love other than paying big bucks from over seas. Recently settled on some slip-on mufflers - NOS Winning Performance brand. Going to coat the inside with heat resistant paint to ward off rust before installing them to see if I can extend their useful life. Hate to add noise but there are not a lot of choices these days when it comes to exhausts.

 

[UncleMike]

I'm considering going 4-1 on the 750, but no pods.

 

[Mark M]

Hey all...
So what's the deal?
Are they worth it?
Are there reasonable gains for the money or should I just fix up the system I have now??

Thanks!

Well, whether it's worth it or not is subjective. There are several things to note, as well.

• A 4-1 will make the most peak power (and torque), but will also have a hole in the torque curve around 1/2 the tuning rpm where the peak occurs. How bad the hole is depends on a lot of things. On my 1100E it really isn't noticeable at all. Smaller engines will probably have more of a dip.
• A 4-2-1 will make less peak power and torque than a 4-1 (not by a lot, but measurable), but should have a smoother torque curve.
• Pretty much any aftermarket 4-1 should be significantly lighter than OEM and offer better cornering clearance. Actual ground clearance is less because of the fat collector sitting under the oil pan. Often, 4-1's require the removal of the exhaust system to change oil. Yes, this is a PITA.
• There are real gains to be made compared to OEM. Your engine will rev harder, make more power and be louder. Just the exhaust will not make huge gains, but you will definitely feel them when riding. Combined with pods, you will see significant performance increase along with a lot more induction noise. Not all systems are the same, some make only a bit more power, some make significantly more.
• I think the 4-1 looks much better, but that is personal opinion.

My 82 1100E had a Kerker 4-1 canister system installed and a big K&N filter installed with the back half of the airbox removed when I bought it. It had been jetted and dyno'd by a local shop in town and gave 102rwhp and 69ft-lb of torque. At 3400ft altitude, with no correction (I think, I am at work, the graph is at home). I put pods on it and re-jetted it (the original shop jetting was OK, but I have it much better now), along with degreeing the stock cams to the stock lobe centers. It is now noticeably stronger than when I bought it and it will pull 5th well past redline. I bet it now dyno's at around 105-108rwhp. I don't know what stock was, but I know it was never over 100hp, probably more like low to mid 90's. So that is a solid 10+% increase, which feels like a lot on the road.

I am planning to fabricate my own true megaphone exhaust tail pipe this year to replace the Kerker can and I expect another solid improvement as the Kerker only has about a 1" diameter outlet on the can. And is still painfully loud.... Mine will have a 2" muffler core and more volume to hopefully cut the sound levels while increasing power some more.

To me, it was worth it. But I also really like the look and sound of the 4-1 and the pods, and I don't mind tuning it until it is right. Not everyone will be the same.


Mark

 

[doctorgonzo]

I think it's mostly look, with slight performance increases. I plan on putting a 4 into 1 on my GS1000 95% because I like the look, and 5% for the various performance gains.

 

[catbed]

ummmmm... you said you were missing a HEAD GASKET bolt? id jump on that as my first priority. dont want to damage the head.

 

[Guest]

Pods add a significant amount of intake snort noise.

Man, do I love that noise. That's probably the best description I've heard yet. I've always described it as animal from the muppets when he gets excited.

 

[UncleMike]

Now you guys are getting me thinking about pods too!

But I want something that's going to require little to no guessing with regards to jetting. I was thinking a simple 4-1 and a Stage 1 and I should be good to go, yes?

 

[Bad Kaw]

Re-read Mark M's post. Without re-stating the obvious - which he did a nice job of - the gains to be made by a properly tuned motor with a 4-1 are factual...not theoretical.

 

[doctorgonzo]

Man, do I love that noise. That's probably the best description I've heard yet. I've always described it as animal from the muppets when he gets excited.

Me too, love it.

 

[Guest]

Man, do I love that noise. That's probably the best description I've heard yet. I've always described it as animal from the muppets when he gets excited.

Pods add a significant amount of intake snort noise. Weight will come down - which boosts performance.

Me too, love it.

:-D

 

[doctorgonzo]

Damn you lucky SOB and your VM carbs. I really wish I could get rid of my CVs.

 

[BigDaddyD]

Do those V&H 4-1's block the oil filter?
I've read that they claim they don't block anything.
Just wondering if that's true or not.

 

[Guest]

Do those V&H 4-1's block the oil filter?
I've read that they claim they don't block anything.
Just wondering if that's true or not.

The V&H isn't too bad... you can get it there pretty good, and the oil drain is not blocked...

But the Jardine I just put on is much closer to the engine. It can be done, but it would be easier with the pipe off.

 

[andrewclaycomb]

All I know is once I put on pods, V&H 4-1 and a Dyna ignition and coils the bike really came alive. It felt torquier. This was on my 78 750. I know some people warned me about selling it, but I am starting to regret selling it so soon because now my new bike is down, being worked on.

 

[kilog55]

i want to do that to my 850 but Nessism mentioned the muffler mount changed in 82 and no one lists a complete exhaust for an 850 but said the 750 would work fine

 

[doctorgonzo]

I'm not touching my stock until ready for a swap for sure. I have TWO missing header bolts, but it doesn't leak. One is sheared off and will have to be extracted, the other I think is just gone. So when it comes off it's probably off for good.

 

[UncleMike]

I'm not touching my stock until ready for a swap for sure. I have TWO missing header bolts, but it doesn't leak. One is sheared off and will have to be extracted, the other I think is just gone. So when it comes off it's probably off for good.

Not that it's great, but missing two exhaust header bolts is a damn site better than two exhaust gasket bolts...

 

[Shin-Ken 1074]

The critical issue with 4-1 systems is that to improve performance, and provide better fuel economy as the engine will be running much better with the exhaust gas being scavanged more efficiently through the 4-1 system is to have the headers tuned to the engine and the muffler designed to work with the headers. Off the shelf items may work and most bikes show some level of improvement but to see what can really happen to your bike fit a tuned system built by an expert. Making tuned headers is an art and it may take time to find someone who is able to build a system, but worth it in my view, cheers.

 

[Mark M]

Off the shelf items may work and most bikes show some level of improvement but to see what can really happen to your bike fit a tuned system built by an expert. Making tuned headers is an art and it may take time to find someone who is able to build a system, but worth it in my view, cheers.

Very true, but you have to remember that most GS owners are not interested in an exhaust system that doubles the value of their bike.

I wish V&H would build a street version of their drag pipes, with the collector underneath the engine instead of beside it. Keep the same short, equal length primary tubes and the true megaphone tailpipe (with a reverse cone to remove the torque drop in the midrange) and a small muffler section after the meg. I would pay new prices for that in a second. But they don't seem to be interested... Guess I will have to make my own, then.

Mark