Building custom pipes for CB1100

[metalmaven_imp]

There are a lot of smart people on this forum and I was hoping that some knew of backpressure and other details when it comes to exhaust.

I am thinking of taking my 4 into 1 and making it 4 individual pipes, two on each side of the bike.. If I run straight pipes all the way back with some simple baffle inserts, does that affect much?? Or will it simply just kick butt.. :biker:

 

[Lord Popgun]

Google Helmholtz resonator

 

[metalmaven_imp]

Google Helmholtz resonator

I googled it. Read it. I just think its a little over my head lol.

 

[metallyguitarded_imp]

You lost me at "...a lot of smart people on this forum..."

 

[Randy B]

Even if you have a 4 into 4 you're still going to want crossovers to connect the pipes as this does a couple of things. The first being it equalizes the backpressure across the cylinders. Second it can help with scavenging and help make a little more power. Third it changes the tone slightly and actually can help keep it a little quieter (if that's what you want). Of course the tone ans noise level will be more greatly effected by the mufflers you choose than anything else.

 

[kDiqq_imp]

Alright, I've discussed this a lot on hot rod forums when it comes to headers and free-flowing exhaust. You want to flow as much air out as possible for big power. Backpressure on modern four strokes is nearly irrelevant and is not needed. I've seen people say 'Oh I dyno'd more power on the 1-3/4" headers over the 2" headers, backpressure matters!' The truth is, if you get headers that don't match the head, you get turbulence and that causes reduced flow. People with 2" exhaust ports that use a 2" primary do see big gains over a 1-3/4" header. Anywho I tangented, you don't need to worry about backpressure. Pipes have a head loss caused by friction between the passing air and the rough surface of the pipe. With as many bends as there are in the pipe, you're going to get some backpressure no matter how much you try to alleviate it. So worry not. It will be there and it is not needed. Keep your primary size consistent with exhaust port size, you'll be fine.

Though, if you want to make more power, a nicely designed collector will provide a scavenging effect. A really nice example is how automotive headers are made, but your 4 in to 4 shouldn't lead to any significant loss in power (or any loss at all IMO) but I HAVE BEEN WRONG and you should never trust me

 

[Inline4_imp]

You lost me at "...a lot of smart people on this forum..."

My comment isn't going to be as eloquent as some here could have posted, but


LOL!!!!!!!! :clap: :clap: :clap: :beerchug: :beerchug: :beerchug:
Just classic! Thanks for the chuckle. :hello:

 

[metalmaven_imp]

Thanks guys! So it would be a lot less work to make 4 individual pipes than it would be make build a crossover into the mix.. Is that a really important thing to have in the exhaust system? I dont want to half ass it, just asking the question..

 

[Cormanus]

One smart member

 

[metalmaven_imp]

One smart member

He looks like he could rip a mean fart, but thats not the kind of exhaust im talking about here..

 

[kDiqq_imp]

Thanks guys! So it would be a lot less work to make 4 individual pipes than it would be make build a crossover into the mix.. Is that a really important thing to have in the exhaust system? I dont want to half ass it, just asking the question..

You're gonna define how important it is. In my opinion, it really isn't. It helps with pulse regulation between cylinders and I rarely see it anymore. It's not a feature in the factory header, so that leads me to believe it's not required.

 

[metalmaven_imp]

Does anyone know if modifying the exhaust or adding an aftermarket pipe voids the warranty??

 

[the Ferret]

Depends on what is being warrantied. Judgement call by mother Honda's reps.

 

[ChipBeck_imp]

Does anyone know if modifying the exhaust or adding an aftermarket pipe voids the warranty??

Metal,

I was a new car dealer for 25 years and am pretty familiar with how this works. Mick has it right but to clarify a bit more, if your mod caused or contributed to the failure then your warranty might not cover you. I say might because I've seen manufacturers cover things that were caused by the owner to maintain good will. So if your exhaust mods caused the bike to run lean and it burned the motor up it probably wouldn't be covered. But if you modify your exhaust and have a transmission or electrical problem that is unrelated to your mod it would be covered. Only failures caused by a mod would be denied.

Dealers want to cover everything because they are reimbursed at full retail rates on both parts and labor by the makers when they do warranty work. I am surprised by how many people think that warranty work comes out of a dealers pocket. Manufacturer reps audit the dealers service departments to keep dealers in line so excessive or incorrect repairs are not being done. Cheers.

Chip

 

[metalmaven_imp]

Does anyone know if modifying the exhaust or adding an aftermarket pipe voids the warranty??

Metal,

I was a new car dealer for 25 years and am pretty familiar with how this works. Mick has it right but to clarify a bit more, if your mod caused or contributed to the failure then your warranty might not cover you. I say might because I've seen manufacturers cover things that were caused by the owner to maintain good will. So if your exhaust mods caused the bike to run lean and it burned the motor up it probably wouldn't be covered. But if you modify your exhaust and have a transmission or electrical problem that is unrelated to your mod it would be covered. Only failures caused by a mod would be denied.

Dealers want to cover everything because they are reimbursed at full retail rates on both parts and labor by the makers when they do warranty work. I am surprised by how many people think that warranty work comes out of a dealers pocket. Manufacturer reps audit the dealers service departments to keep dealers in line so excessive or incorrect repairs are not being done. Cheers.

Chip

Metal,

I was a new car dealer for 25 years and am pretty familiar with how this works. Mick has it right but to clarify a bit more, if your mod caused or contributed to the failure then your warranty might not cover you. I say might because I've seen manufacturers cover things that were caused by the owner to maintain good will. So if your exhaust mods caused the bike to run lean and it burned the motor up it probably wouldn't be covered. But if you modify your exhaust and have a transmission or electrical problem that is unrelated to your mod it would be covered. Only failures caused by a mod would be denied.

Dealers want to cover everything because they are reimbursed at full retail rates on both parts and labor by the makers when they do warranty work. I am surprised by how many people think that warranty work comes out of a dealers pocket. Manufacturer reps audit the dealers service departments to keep dealers in line so excessive or incorrect repairs are not being done. Cheers.

Chip
Thanks Chip that makes sense. I am still thinking of modifying my exhaust, It is definitely going to happen at some point. I am almost done with the backrest too so that will free up some brain powerrrr.

 

[StreetFighter_imp]

There are a lot of smart people on this forum and I was hoping that some knew of backpressure and other details when it comes to exhaust.

I am thinking of taking my 4 into 1 and making it 4 individual pipes, two on each side of the bike.. If I run straight pipes all the way back with some simple baffle inserts, does that affect much?? Or will it simply just kick butt.. :biker:

It would allow the bike to breathe but you would likely lose a lot of low end torque from it.

Now, considering doing that to a cruiser would have required a stage 1 jet kit, I'm not sure if you would need some type of update to the mapping or not.

 

[Ole]

If you do this, and your low end torque is down, incorporate 4 Snuff Or Nots into your system.

remember them? I do because I is old

 

[the Ferret]

Had them on my CL77 lol. I is older than you

 

[metalmaven_imp]

If you do this, and your low end torque is down, incorporate 4 Snuff Or Nots into your system.

remember them? I do because I is old

Snuff or nots.... huh, I might have to google that one lol

 

[flynrider]

Manually operated baffle-like devices. Ostensibly so you could open your scrambler's pipes off road, and muffle it on road.

As I recall, most people with Snuff or Nots, just left 'em open all the time