S1 Publishing(Oxford)© 1999-06

World of motorcycleS
S1 Publishing(Oxford)© 1999-06
Exhausts-The Basics
This is just a general guide.
If you are about to do your own maintenance, using these pages, I take no responsibility if you get things wrong!

 Collars are the means the engine manifold manages to hold the downpipes. There are several different of collars, most have two holes which fit over two studs in the engine manifold. They come in singles or as two parts for each downpipe. In some cases they screw in, (e.g. Suzuki GT's). They very rarely need replacing.
Exhaust Gaskets
These are usually made out of a hollow copper ring. The reason they are hollow is that as the exhaust is clamped into the manifold they crush when the exhaust clamp is tightened making a airtight seal between the exhaust and the manifold.
 It is usually best that they are replaced every time the exhaust is removed from the engine.
Down pipes from a 4 to 1 system.
Note the flange on the end. the collar fits over this
Down pipes.
 The pipe that connects to engine manifold to the silencer or "can"
 Occasionally these get holes in them after a few years of use. These holes can be filled in most cases, but the best thing you can do if this happens is to replace them, as any repair can only be a temporary fix, and the fix won't ever look as good as a new pipe.
 There are 3 types of temporary repair, you can braize the hole. You can weld it, if it's just a small hole, just drop a blob of weld straight on the hole. If the large is too big for that, then a steel plate can be formed to fit, then welded around the edges, leaving an airtight seal.
 If you cannot weld, then a wire bandage will do the job. It doesn't look pretty, but it will get through you (if you do it a good job, it has even been known to pass a British MOT).
If you want to know more, click here
Collector Boxes
 These you only find in multi-cylider engines, and even then, not all engines have them.
 They are a pipe, or box which connects between downpipes underneath the engine.
 The job they are there is to equalize the flow of the exhaust gasses from the other separate cylinders.
 They also seem to collect moisture too, from rainfall, or consendation,. As the are usually lowest part of the exhaust the moisture collects there and these can lead to holes. These holes are usually worth repairing, depending on the location of the hole(s)


A  "can"
 Silencers or "cans" & baffles
 The silencer consists of two main parts, the "can" is the outside part of the silencer, inside the can you find the baffling
 Baffles, or baffling, in most standard four strokes, is designed to firstly reduce noise and secondly with some modern machinary, to remove harmful emmisions. Most cannot be fixed, but be replaced with a complete can.. One reason baffles to be burn out after several years or through heavy use.
 There is no real cheap fix for repairing the cans either, by the time they rust out and get holes, they are too thin to braize or weld, and even though you might the wire bandage I described earlier, it won't last very long on this part.
 In the case of some Moto X and other off road machinary, you can and remove or adjust the amount of baffling.
Silencers or "cans" & baffles

Some two stroke baffles can be removed for cleaning, this is not true when it comes to two strokes with expansion chamber, which cannot be removed for cleaning. Like the cans on four strokes, when they begin getting holes, they need to replaced, and there is nor real way of repairing them.
 When it comes to old syle machinery, as well as smaller two stroke engines, there is usualy a screw in a hole in the open end (back of the machine) of the exhuast. If you indo the screw, and with a good set of pliers, the baffle will come out (usualy a lot of twisting and pulling is involved).Inside you will usaly that is is covered in unburnt two stroke oil, and is very to remove, sometimes it is better to replace them. If you have clean them, then you'll need a petrol/parrafin bath for them to soak into.Then it's just a case of using a hard brush to remove the worst of it.I have been told there are other means to get the job, but the involve chemicals and more take has to be taken. So I'm not going to go it to them.


This is just a general guide.
If you are about to do your own maintenance, using these pages, I take no responsibility if you get things wrong!