Fitting a new exhaust to your motorcycle
Stock silencers on today's motorcycles seem to be getting bigger and fatter, while the sound just gets thinner. Fortunately, the aftermarket suppliers offer rear silencers and complete exhausts that are lighter, sound better and offer an eye-catching custom look.
Replacing your exhaust: a popular tuning measure for motorcycles
It's not just about looks. These aftermarket systems generally offer better performance – even the street-legal versions – with a noticeably more linear torque curve and improved ride dynamics thanks to the much lighter weight. Changing your exhaust is really quite simple in most cases. Not for nothing is fitting a new exhaust system right up there at the top of the list when it comes to motorcycle tuning and styling.
Owners of the current generation of naked bikes and sport bikes (with electronic fuel injection) now have options to jazz up the look of their bikes that would never have been street legal in the past. Just take a look at the Hurric Supersport Exhaust with its ultra-short, snappy look – what more could a biker ask? And as if that wasn't enough, it comes complete with EC type approval! So no tedious trip to the test centre to have it approved, or the hassle of carrying proof of road legality around with you – because the marking on the exhaust says it all! And if you want to enjoy a real race sound (but please – only on the race track or privately owned land), most aftermarket silencers are now supplied with a removable dB absorber (dB killer).
Just removing the dB absorber, or just using a K&N permanent air filter, usually still falls within the control range of the electronic fuel injection system, which ensures the correct air-fuel ratio. It's generally only with a combination of tuning measures (such as sport air filter plus removed dB absorber) that you need to start thinking about enriching the fuel mix (e.g. in the form of a Power Commander). This also applies if you fit a proper race exhaust system, which is not approved for road use. If your motorbike has carburettors, it will largely depend on the model of bike as to when you need to adjust your air-fuel ratio – if you're only fitting an EC type-approved silencer with dB absorber, you will seldom need to add bigger jets. But it will be essential, in most cases, if you do more extensive aftermarket tuning (exhaust plus air filter with increased flow). After any customisations, we therefore recommend checking the appearance of the spark plugs and looking for any other indications that the engine is running lean, such as backfiring when you take your foot off the gas, or increased engine temperature. And what about catalytic converters?
Since 2006, motorcycles have been required to pass an emissions test similar to the one for cars. If you change the exhaust of any bike built from 05/2006 onwards, the aftermarket exhaust must also be fitted with a catalytic converter in order to comply with exhaust emission standards. If you're lucky, the original cat may be housed in the manifold – in which case your aftermarket exhaust does not need to have one. Motorbikes prior to 05/2006 do not need a cat to meet the exhaust emission standards, and this still applies if you fit an aftermarket exhaust.
Fitting an aftermarket silencer: our example shows a Hurric Supersport with cat on a Kawasaki Z 750, built 2007 or later
Before starting work, jack up the motorbike and secure it against toppling over. Lay something soft, like a blanket, on the floor so that you have somewhere safe to put both the original parts and new add-ons without them getting scratched.
Removing the stock exhaust
First undo the screws on the manifold clamp, the midpipe bracket and the rear silencer bracket on the motorcycle frame. Make sure you're holding the silencer securely when you take the last screw out of the bracket so that it doesn't fall to the ground.
Turn the silencer outwards and clockwise and remove the black cap on the actuator of the control shaft by undoing the two hexagon socket head screws.
Before detaching the cables on the control shaft, you will need to undo the hex nuts holding the cables. After detaching the cables of the actuator, use cable ties to secure them out of the way on the motorcycle.
Caution: the "decommissioned" cables must not be permitted to come into contact with any moving parts, so it's best to tie them up well out of the way of the chain, sprockets, rear wheel and swing arm! You can also remove the cables completely if you prefer, although this can lead to an error message on the instrument panel, which in turn could result in the bike only running in safe mode. At the least you will have a permanent error message, which would then have to be deactivated via the electronics. This is a job that can only be done by a motorcycle workshop.
Pre-mounting midpipe and rear silencer
Insert the Hurric midpipe in the original manifold and loosely pre-mount the manifold clamp.
Push the Hurric silencer onto the Hurric midpipe all the way. Align the silencer and the midpipe so that the exhaust system is parallel to the motorcycle. Push the carbon clamp over the Hurric silencer and attach it to the original bracket on the frame of the motorcycle using the original fastenings.
Insert the springs in the spring eyes provided for this purpose. This is generally easier if you use a proper spring puller tool.
Aligning and fixing the silencer
Align the silencer with the bike and ensure tension-free installation – this is important to avoid the risk of vibration damage. If the exhaust will not rest against the mounting point on the frame in spite of all alignment attempts, it's best to insert a thick spacing washer rather than simply tightening the entire system against the frame using the bolt. Finally, tighten the M8 screws on the frame bracket and on the clamp of the midpipe with a torque of 21 Nm. Once you've finished installing your new silencer, and all parts are properly secured, you can carry out your first sound check. And we promise you, that sound will put a smile on the face of any biker!
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The Louis Technical Centre
Problems getting spare parts? Or maybe you've got a technical question about your motorcycle or an accessory The Louis Technical Centre can help! Remember to quote all the necessary details of your vehicle – better still, send us a copy of your registration document.
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These tips for DIY mechanics contain general recommendations that may not apply to all vehicles or all individual components. As local conditions may vary considerably, we are unable to guarantee the correctness of information in these tips for DIY mechanics.
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