Exhaust pipe question - where is the CAT?
- Thread starter sam2019
- Start date
But you also get rid of the O2 sensor surely.
Carby models would have no 02 bung, no bump/ no cat.
Next model had O2 bung, Bump and Cat horizontally mounted.
Then it had an O2 bung and a Bump/Cat mounted Vertically and closer to the exhaust port thereby allowing the Air injection to be deleted?
That's my understanding anyhow!
One thing they all have in common is their purpose.
Which is to allow the exhaust Gasses to escape ( I am disregarding the emissions and noise concerns) and the better the Gasses go out the better you can get them in.
We have seen modified Air filter covers that are available at a price, the first iteration was an OEM cover trimmed down on a Lathe.
Then the super metal one.
Oh nearly forgot, the other thing the header pipes have in common is the wonderfully useful restriction ( I wait to be informed of its importance) do the Math.
OD of header is 43mm the OD the end that accepts the Muffler is 35.5mm about a 17% decrease in diameter of the OD which is both directly relative to the ID and when expressed in Square Area is considerable
Carby models would have no 02 bung, no bump/ no cat.
Next model had O2 bung, Bump and Cat horizontally mounted.
Then it had an O2 bung and a Bump/Cat mounted Vertically and closer to the exhaust port thereby allowing the Air injection to be deleted?
That's my understanding anyhow!
One thing they all have in common is their purpose.
Which is to allow the exhaust Gasses to escape ( I am disregarding the emissions and noise concerns) and the better the Gasses go out the better you can get them in.
We have seen modified Air filter covers that are available at a price, the first iteration was an OEM cover trimmed down on a Lathe.
Then the super metal one.
Oh nearly forgot, the other thing the header pipes have in common is the wonderfully useful restriction ( I wait to be informed of its importance) do the Math.
OD of header is 43mm the OD the end that accepts the Muffler is 35.5mm about a 17% decrease in diameter of the OD which is both directly relative to the ID and when expressed in Square Area is considerable
Last edited:
the BS4 has no lambda??
My error
My understanding is the old BS3 header pipes have no cat but I could be wrong. This outfit makes a header pipe.
htexhaust.com
But seems like they not set up to ship overseas.
Bend pipe (OE Type) - FOR Himalayan & Scram 411 / Ht exhaust - bend pipe only - SB 741 - Ht Exhaust
Hi-tech EXHAUST BEND PIPE
htexhaust.com
thanx, but I can really just use the BS3/carby header pipe and add a hole for the o2 sensor. That should be easy enough.My understanding is the old BS3 header pipes have no cat but I could be wrong. This outfit makes a header pipe.
But seems like they not set up to ship overseas.Bend pipe (OE Type) - FOR Himalayan & Scram 411 / Ht exhaust - bend pipe only - SB 741 - Ht Exhaust
Hi-tech EXHAUST BEND PIPE
EDIT: I only now realize this in in India!! and cheap!! and they provide for the O2 sensor attachment. I am going to get one!
that solves the riddle where the BS4 has the cat. so I really need a BS3 pipe.
A cat does not need any electronics to do its thing. That is why my stock standard carby has them too. A cat is just a honeycomb made from metals (platinum/rhodium, etc) that when it gets to the right temperature it acts as a catalyst for engine emissions to further oxidise/burn. That's why on BS6 it was moved closer to engine exhaust to guarantee hotter temperatures and to meet higher standards.
Dool have u had experience with buy stuff from India with companies like this? I would like a pipe like that.No, you really need to buy that header pipe and cut off the end and use a slip on Muffler
Good price considering it includes the Fittings to hold the Heat shield that normally covers the Cat.
well, it takes time. and there is customs duty. but so far everything has reached. I could order a few and send them to Dool. just sending one will be expensive as parcel are calculated by size more than weight and this item is big but 3 of them wont be much bigger so shipping should only increase marginally. Packing will be a bitch and I have to check if they are not oversized for mail service. 105 AU$ a pop in case we get that to work.
