Motad exhaust, chop?

[andy_sheff]

I'm thinking of chopping the end off this for cosmetic reasons and to make it louder. Any one got any experience of this sorta thing ?

[matthewmosse]

It may mess up your jetting on the carbs, it may attract attention from the law and it may annoy people - depending on how loud. Also you may get MOT issues, especially if it's obvious that you've modded things. Personally I got fed up with the noise from my loud pipes  and sought out a motad off ebay to give my ears a rest. Cosmetically chrome will not overpaint easily, and the cut edge will rust so getting a tidy finish might be tricky. Getting used exhausts re chromed is really tough if not inpossible. I had a mate who used to drill the baffles out and another who thought ramming a steel bar up the silencer to demolish the baffles was a good idea, they sounded louder but I'd say they also didn't run so well, both bikes subjected to this kind of mod were less reliable then my older, higher milage bikes that I kept as the manufacturer or motad intended they were made to be used - at the end of the day there is a lot of research and science behind getting the back pressure right etc and whilst you can on some bikes achive more power if you know what you are about, most of the time there isn't much inprovement to be had without hours spent re jetting and needing to fully understand what is going on. It could be a can of worms in other words.

[SteveD CB500K0]

A few years back, my mate Jim in Camberley had a 750F1 with a Motad and asked the same question. Difference is, he asked Motad!

... and they said...

http://forums.sohc4.net/index.php?topic=5122.0

[matthewmosse]

Interesting. Cann't say I've had new motads on anything bigger than a 125, maybe mine had already been got at or more likely internally rotted out  given their age, running wise the Neta was better than the chrome one for what that's worth , but cosmetically it was not pretty. For loud the laser system was pretty noisy but loudest was the bsm with triuph rockett 3 silencer welded on. Those last 2 were in conjunction with K&N filter but std air mixing chamber and I'm pretty sure up jetted carbs off a 500, there was deffinately more power but when I tried the same on 550/k3 carbs it was rubbish to start and low on power.

[andy_sheff]

I see, I'm not scared about out digging deep in this exhaust and removing all it's internals.

[andy_sheff]

It's not for the performance by the way, it's for noise and looks, I'm not concerned over a few bhp!

[matthewmosse]

Depending on what carbs you are using the effects could be barely noticeable or quite bad - my expirience of carbs on sohc bikes is limmited to 500's which are very tolerant I feel, - and the k3 were my other bikes and both were tempremental and difficult with anything other than good condition exhausts and stock airbox or re jetting whic to be honest I really couldn't be bothered with, especially with the chore of removing the carbs off the bike.

[andy_sheff]

Yeah Matt I know what you mean, jetting etc its all a pain in the arse. I've seen many 750s on the net, mainly yanks, with open pipes and just running headers etc etc so I guess it can't be so bad ey

[K2-K6]

I don't feel that these motors run very well unsilenced at all.....the cam, the carbs, ports etc have been designed to run with a reasonable amount of sound suppression and you can chase around alot trying to get it anywhere near decent overall response if you get rid of all silencing.

To qualify that....they do sound and can go better with a bit less restriction....and if you want to cut out the endplate and fabricate a decent free-flow baffle to fit inside the rear section, then you should be able to get quite a good compromise, without having to chase after it with big changes in jetting.

[andy_sheff]

Interesting, and makes sense,  now in not so sure what to do. Perhaps cut the end off and just remove some of the baffle and leave some in there

[matthewmosse]

My mate literally hammered a steel spike to demolish the baffles on his xs250, worked moderately well on the first silencer but the second went less well as the steel spike ended up lost inside the silencer, completely lost and adding a fair bit of weight. Beyond the jetting issues either a really long drill or spike of fairly large diameter would deal with the baffles without cutting the end off the silencer - getting a tidy end cover made up would be possible and that would be the potentially be the make or break detail on this kind of job. The advantage would be that you could then both remove or add baffling to suit - I'd try to source the new backing plate before cutting the old one off as that will be the hard bit to get cosmetically right.

[andy_sheff]

I don't think an open end will look bad tho, it's a big bore pipe but the bikes gonna be a bit offensive anyway

[andy_sheff]

Unless I can just buy a different can for it, ile have to look tomorrow