Topic: What is up with my exhaust pipes setup.

[AddLightness]

Hello SOCH4,

I'm new here on the forum, and I am also new to the CB bikes. Having looked at many different pictures of the CB350, I now realize that what I bought last week (a 72 model), does not have a stock exhaust pipe set up. Is anyone familiar with the exhaust on my bike. I take it that it was done this way to get cylinders 1 and 3 and then 2 and 4 to fire out of the same exhaust. Thanks for any input, I definitely like this place and man is there a ton of info I need to read through!

Martin

[seaweb11]

Photos would be a great help in coming up with an answer to your question.

I believe the CB 350 should have a 4 x 2 exhaust system.  If all four are collected into one pipe it would have to be an after market set up.

photos?

[Gordon]

Stock 350F pipes are 4 into 4, but not many have made it this long.  They were thin and rusted out quickly.  The most common replacements were slip-on mufflers that used the stock headers and turned the exhaust into a 4 into 2, which sounds like what you have. 

[camelman]

I have a 4-2 setup on mine and love the sound.  Can you try posting pics again?  There is a size limit that you might have surpassed with your first round of pics.

Stock pipes were the 4-4.  Sweet look, but short lives.

Camelman

[flybox1]

yep, most dont have stock.
pretty rare to find ANY original 4into4's not rusted out like swiss cheese.
they are, as some say, "unobtanium"
thechrome was thin.  pitted/rusted fast.
back inthe day, tons of these got the Jardine 4into2's when the originals went bad. some got the SS style 4 into 1's
new pipes these days are ($1000)MIVV's, or a (~$350) MAC 4into1.

[vames]

Does anyone sell just the 2-1 slip on mufflers that fit original headpipes?

[flybox1]

if they do, i havent been able to find them   
i'm needing new cans as my 30+year old Jardines are a little past pitted underneath. 

[AddLightness]

Yes, pictures would be helpful. I guess it is a size limit. What is the limit BTW?

Martin

[Gordon]

Well, you have the same mufflers that most 350F's ended up with, but those definitely aren't the stock headers.  Stock is 1/2 on the left side and 3/4 on the right.

[The_Crippler]

Well, you have the same mufflers that most 350F's ended up with, but those definitely aren't the stock headers.  Stock is 1/2 on the left side and 3/4 on the right.

I read those as fractions and was really going to have to question that...   


Another good general rule (for the next time you pick up a bike) on stock vs not pipes is what color the headers are.  Many aftermarket pipes blue significantly up at the top, where-as most stock ones don't.   It's not infallible, but it's fairly reliable.

[Gordon]

Well, you have the same mufflers that most 350F's ended up with, but those definitely aren't the stock headers.  Stock is 1/2 on the left side and 3/4 on the right.

I read those as fractions and was really going to have to question that...   

You mean you don't have the stock 1 & 1/4 exhaust system?

[The_Crippler]

I was more concerned with how you'd get half the pipes on one side, and three-quarters of them on the other.

[AddLightness]

Alright, ya'll are a bunch of comedians    Thanks for the laugh.

Is there any reason you think it was set up with 1 and 3 on one side and 2 and 4 on the other?

Martin

[TwoTired]

Alright, ya'll are a bunch of comedians    Thanks for the laugh.

Is there any reason you think it was set up with 1 and 3 on one side and 2 and 4 on the other?

Martin

Yes, it has to do with the firing order of the exhaust pulses.  You don't want the exhaust pressure pulse from one cylinder to foul the exhaust scavenge from another.  Or, you'd like the exhaust pulse form one cylinder to help smooth the exhaust velocity to better scavenge the other cylinder.
  The firing sequence is 1,2,4,3.
The crossover is supposed to make the exhaust scavenge more efficient at normal street speeds.  Therefore, more low and midrange power.

That's the functional theory.  Implementation is, of course, another matter.

Cheers,

[bryanj]

sstandard 350/4 exhausts are now available again look on Dave Silvers website