Cat dissection

[Deak]

Nope not the furry flea ball kind. I was just wondering if anybody has considered splitting the catalytic converter, removing the innards and welding it back up again.

I remember a thread a while back about the difference a collector box makes to the exhaust noise with it being a lot deeper with an ‘echo-chamber’ effect. I’m sure that the empty cat box would give this effect.

I had a 750 Bonneville in the late 70’s with an exhaust system made by a company called Campbell Geometrics and this used a 2 into 1 system with an alloy collector box and then a short adjustable baffle megaphone. The sound from this was simply awesome. I remember my Dad saying he could here me leaving work 10 miles away. It was reminiscent of a Spitfire airplane engine at full throttle. I’d love to recreate that sound on my GS.

Has anybody got a cat converter surplus to requirements they are willing for me to experiment on?

 

[Jimb]

I thought about this before I got a Y piece and the guys at Rainbow had one from a scrapper that was all bent up and inside its all welded up to the outside casing so its a non starter, there is actually a connector box as well as a Y piece available from Touratech, I have seen one on an ADV and it does give a lower sound.

 

[(RIP) Kaister]

I used to have a bonneville - early 80's meriden - which had an assortment of pipery at various times, ranging from nothing at all on the headers to a unity equipe 2 -1 with a 'tulip end' muffler or 'goldie' on the end.

The 2-1 was about twice as loud as open pipes.

The bm with straight through remus and no cat is positively quiet after that.

Same firing order - though.

Its amazing what we got away with back then - but it was in Devon.

Phil

 

[Zwerver]

As far as I know, the chairman of the Dutch Gs-club, Rene,
has been experimenting with it.. His forumname: Dirtmaster...

 

[Chris G]

I did this, it works okay, not the easist job in the world, cos the cat is twin walled and is near indestructable.

I cut a slot in the end with a jiggsaw, and then set about the internals with a big drill bit [wear a dust mask or keep the inside wet - to prevent breathing the dust], when all the cat was out [bout 2 hours] welded plate over hole, - job done

 

[Randy]

I did this, it works okay, not the easist job in the world, cos the cat is twin walled and is near indestructable.

I cut a slot in the end with a jiggsaw, and then set about the internals with a big drill bit [wear a dust mask or keep the inside wet - to prevent breathing the dust], when all the cat was out [bout 2 hours] welded plate over hole, - job done

And?

 

[Shaunie]

Am I right in saying that some imported 1100 GS's don't have a cat?

If so, what's in the collector box?

I'm pretty sure mine is catless 'cos there's no lamda probe.

It still sounds shit though.

 

[Wreford Miles]

As a kid I had a Honda C90 field bike, I read in amagazine about tuning exhuast and the theroy that there's an optimun lenght from the exhust vale to the end.

Seem to remeber it was 44 1/2 in on an Austin A40!

Anyway fond a bit of straight pipe that ws a slide fit over the down pipe on the Honda and with the bike on the stand and running at what seemed about 2/3rds max revs i slowly moved the pipe an in one point the exhuast note changed to a higher pitch and the revs rose without anymore throttle.

Bottom line: I could now rev the Honad till the rings broke and the sound would hurt your ears.


Sorry nothing to do with ripping the guts out of a Cat...