Topic: Weight savings with a 4-1 vs a 4-4

[gregwaits]

As much as I love the symmetric appearance of my K8 with the stock 4 into 4 pipes, it has been pointed out to me how much dead weight I can trim off if I switch over to a 4-1 set up. And aside from the weight advantages, it performs better too (that's what I hear).

How much weight difference is there anyway? My buddy says I'd lose at least 50 pounds. That would make a helluva difference in performance (acceleration and cornering), so I am seriously considering it.

Now, how can I convince the wife that I need to spend another 300 odd dollars on a bike that already looks pretty good? 

[Gordon]

Unless your buddy knows of a 4-1 system that's lighter than air, he's exaggerating just a little.  

I don't know the weight of the stock K8 4-4 pipes, but a set of 550K 4-4 pipes only weighs 25 lbs.  I can't imagine that the K8 pipes would weigh so much more that it would even be possible to create a 4-1 that would weigh 50 lbs less.   

[Gordon]

I'd say you can probably drop around 20 pounds with a 4-1.

And you'd also lose the cool factor of the stock pipes...

[ekim98]

I was told that a complete stock 750 exhaust system is about 38 to 45 lbs, but I don't know for sure. I do know that my MAC 4 into 1 only weights 13lbs- 4 ozs. as I mounted it, so it did save some weight.

I would prefer a 4 into 4 cr look or even a nice 4 into 2 but they cost to much imo.

[TwoTired]

"Performance" is a subjective term.  Good 4 into 1 design uses the exhaust velocity from other cylinders to help scavenge the cylinder that is currently on the exhaust stroke.   Proper 4 into 1 design makes this only occur in the upper RPM band, such as what you would use in drag racing or track "performance" where peak engine power is needed all the time.  Below that optimum RPM band, such as cruising about town and highway functions, the interference of neighboring exhaust pulses are actually a detriment to cylinder scavenging.
If you plan to keep the engine wound tight in the HP band and you plan on re-jetting the carbs to take advantage of this benefit, a 4 into 1 that is designed to take advantage of its benefits (not all are) is a step up.  For everyday use, you will lose low and midrange "throttle twist performance" and be more dependent on down shifting to get that HP boost.

The are also the extra costs of ear plugs to consider...

Did I mention that not all 4 into 1 exhaust designs are made to provide a performance boost?  Many are simply made to look like they might.  Pipe diameter, length, and internal baffling in the silencer determine if, and at what RPM, a "scavenge effect" takes place.  I don't believe the MACs, for example, have any scavenge effect inherent to their design.  This choice is simply a looks, sound, and economy decision.  IMO.

Cheers,

[MCRider]

I was told that a complete stock 750 exhaust system is about 38 to 45 lbs, but I don't know for sure. I do know that my MAC 4 into 1 only weights 13lbs- 4 ozs. as I mounted it, so it did save some weight.

I would prefer a 4 into 4 cr look or even a nice 4 into 2 but they cost to much imo.

I agree with the two above. I'd always heard the difference between stock and a Kerker for example was 20 pounds. The Kerker has a larger muffler than the MAC, so that makes sense with ekim98's experience.

[ekim98]

"Performance" is a subjective term.  Good 4 into 1 design uses the exhaust velocity from other cylinders to help scavenge the cylinder that is currently on the exhaust stroke.   Proper 4 into 1 design makes this only occur in the upper RPM band, such as what you would use in drag racing or track "performance" where peak engine power is needed all the time.  Below that optimum RPM band, such as cruising about town and highway functions, the interference of neighboring exhaust pulses are actually a detriment to cylinder scavenging.
If you plan to keep the engine wound tight in the HP band and you plan on re-jetting the carbs to take advantage of this benefit, a 4 into 1 that is designed to take advantage of its benefits (not all are) is a step up.  For everyday use, you will lose low and midrange "throttle twist performance" and be more dependent on down shifting to get that HP boost.

The are also the extra costs of ear plugs to consider...

Did I mention that not all 4 into 1 exhaust designs are made to provide a performance boost?  Many are simply made to look like they might.  Pipe diameter, length, and internal baffling in the silencer determine if, and at what RPM, a "scavenge effect" takes place.  I don't believe the MACs, for example, have any scavenge effect inherent to their design.  This choice is simply a looks, sound, and economy decision.  IMO.

Cheers,

 Your probably right about the mac not being a performance pipe per say , but you/I can tell some difference when you get the rpms up that it "seems" to kick in some., but I don't know if its a real gain or just getting into the good power range. Mine probably doesn't help that much as it is quite quit even in the upper rpms range. For me cost and a look were the main factors over performance.

[firecracker]

You should definitely get rid of that heavy 4-4.




...then sell it to me.  

Forget weight.  I'll lose the 20 pounds myself to get that look.

 

[Gordon]

Now, how can I convince the wife that I need to spend another 300 odd dollars on a bike that already looks pretty good? 

IMO, if your stock system is in decent shape you can find a lot better things to spend $300 on than a new 4-1 exhaust. 

And yes, I'm talking about spending that money on other things for the bike!  

(like a Dyna-S, some pods, and a couple of in-line fuel filters _{just for TT}

[ekim98]

With the mac and pods I installed I probably didn't gain much but my 1/4 speed/times shows I didn't loose any performance so it was a fair trade imo.

[Gordon]

With the mac and pods I installed I probably didn't gain much but my 1/4 speed/times shows I didn't loose any performance so it was a fair trade imo.

How is that a fair trade if you spent extra money on a new exhaust and pods and didn't gain anything in return?

[mlinder]

New Math.

[ekim98]

With the mac and pods I installed I probably didn't gain much but my 1/4 speed/times shows I didn't loose any performance so it was a fair trade imo.

How is that a fair trade if you spent extra money on a new exhaust and pods and didn't gain anything in return?

New math = less weight than rusted out 4 into 2 exhaust. Pods = less weight + cheaper than replacing old rubbers, clamps and better looks imo than stock air box and still have the same performance so I call that a fair trade off. If it had the stock pipes then it would have been a loss.

[Clyde]

I just shipped a set of Z1 pipes and they weighed 25 kgs (55lbs) boxed.
The box and foam packing is probably around 3-4 kgs, so I estimate the pipes are around 22kgs/48lbs.
A CB750 would be comparable and my old CB750 4-1 weighed about 10kgs or 22lbs.
I am not sure of any performance gain as I did not put the bike on a dyno, but my view was always that the main difference was the weight reduction.
It seems that most people are doing the opposite now and going for the original look. Certainly in Australia a 750 is worth a lot more with 4-4 as people want and are willing to pay for original pipes.

[MCRider]

I just shipped a set of Z1 pipes and they weighed 25 kgs (55lbs) boxed.
The box and foam packing is probably around 3-4 kgs, so I estimate the pipes are around 22kgs/48lbs.
A CB750 would be comparable and my old CB750 4-1 weighed about 10kgs or 22lbs.
I am not sure of any performance gain as I did not put the bike on a dyno, but my view was always that the main difference was the weight reduction.
It seems that most people are doing the opposite now and going for the original look. Certainly in Australia a 750 is worth a lot more with 4-4 as people want and are willing to pay for original pipes.

I just cringe thinking of all the stock systems that ended up in the landfill in favor of 4-1 back in the day.   

[rhinoracer]

4-1 and 4-4 pipes weight about the same so the major weight savings are in the silencer.

My Supertrapp weighs around 2 lbs. probably less.

[754]

I clearly remember taking my 73 set to the dump, along with a set of k2 4-4s..

[rhinoracer]

I clearly remember taking my 73 set to the dump, along with a set of k2 4-4s..

OK, but how much did they weight? 

[ekim98]

I clearly remember taking my 73 set to the dump, along with a set of k2 4-4s..

OK, but how much did they weight? 

Someone on here said stock mufflers weight approx. 7-1/2 lbs. each, if I'm remembering right! I've never had any stock mufflers to weight, so I don't know for sure.

[gregwaits]

A mechanic I know has a set of aftermarket 4 -1 drag pipes. The pipes dump into the one pipe under the bike. It has no muffler, so if I was to buy these from him ($50) I will have to deal with that, or get a muffler shop to fab me a tailpipe that would flare out to the side so I could secure it on the frame.

But by then it probably would end up costing me more than a new Mac set anyway. Grrrr.

[goon 1492]

get even lighter exhaust... Pay big bucks for some titanium customs made.  then top it with some kerkers

[754]

GREG, if you got a pic we may be able to ID or help out with a baffle..

[MCRider]

A mechanic I know has a set of aftermarket 4 -1 drag pipes. The pipes dump into the one pipe under the bike. It has no muffler, so if I was to buy these from him ($50) I will have to deal with that, or get a muffler shop to fab me a tailpipe that would flare out to the side so I could secure it on the frame.

But by then it probably would end up costing me more than a new Mac set anyway. Grrrr.

If the collector is long enough you may find a baffle at an auto parts store that will slip in. Drill and pin it from the side. Also, you may find a baffled cheapo chrome tailpipe tip. I've seen some bikes with these setups and thought they were pretty good on the cheap.

I had one once (header with no muffler) and took an old baffle out of a CB750 stock pipe, had a weld shop weld round plates on each end that were the diameter of the collector, slipped it in drilled and pinned it from the side. Cost about $20 labor and sounded real good actually.