Loud Exhaust Fix.

[chrisa]

So... I've been a bit concerned about the RT (2015) noise factor. It gets louder the longer you ride. So, after reading a post on here about an end cap you can fit to the outlet that seems to work a bit I decided to have a think.

I stripped the exhaust. The packing inside is very glass fibery. I removed it and put in the bin. The exhaust seems to have two sections or zones, three if you include the end cap. Right at the bottom 'around the bend' there was very little if any packing. I'm unsure if that section is perforated...but regardless I bought some packing fibres, not the cloth - I used this on my KTM to good effect as you can pack the stuff into any shape unlike the cloth variety - and using a pokey thing got plenty of packing in there. Then I fitted 5mm or so (once around) of exhaust mesh along the length of perforated tube and fixed in place with wire. The mesh is stainless steel and very loose knit, the idea being to create an expansion area internally to receive some of the 'pop' as the gases go through the silencer. Replaced the tube of the exhaust and packed it. So, just the end cap left.

The inner plate of the end cap comes apart in much the same way as the KTM. I removed this. Over the final outlet (inside the end cap), which is kind of oval shaped, I put a tea strainer domed in the direction of flow and held it in place with more mesh. I hoped the mesh would also take out some of the noise by resonating. Tea strainer mesh was all I could find on the day but will probably change this for a different mesh with larger holes at some point. Assembled and riveted the end cap on. Fitted to bike. Warmed up the bike.

From the start it was obvious that this had made a very noticeable difference, so to confirm that it hadn't lost power I went for a road test. Maybe the tiniest amount but the bike goes very nicely and popped the front just as easily as before.

Back at the garage I prepared phase two! A 28mm X 22mm end feed reducer. The 22mm socket end was carefully ground down to create an interference fit (i.e it needed a mallet to 'tap' it in. I inserted another rolled piece of knitted exhaust SS mesh. See pic. Then drilled down through the mesh and out the other side of the fitting into which a long self tapping screw was inserted, ground off the excess. Started the bike and offered it on/off the end of exhaust outlet, revved it up to see if any difference. A VERY noticeable difference, especially to the 'after burble' when you close the throttle. Great. Tapped it into exhaust. (Note: the last picture below doesn't show the fitting tapped in all the way. It obviously goes in as far as the taper of the fitting). Went out for an hours ride this evening - it's a brilliant mod. The sound is now nice and smooth. The weird thing is I expected the power to be killed quite a bit, but it's absolutely fine. I would say you have to crack the throttle a little more than before to loft the front but I mean a little.

Time will tell if this lasts. The packing will last of course. My only point of concern is the tea strainer which may or may not carbon up. We'll see. But really happy. For £15 I've got a properly packed exhaust and I estimate 50% quieter.

Patent pending. Patent pending. :-)

Edited May 2, 2015 by chrisa

[lineaway]

Yes, that will clog up in time. You just made yourself an unofficial U.S. spark arrestor!

http://lewisportusa-com.3dcartstores.com/SPARK-ARRESTORS_c_157.html

Edited May 2, 2015 by lineaway

[chrisa]

Hi.

Yes, the tea strainer may well do. The wire mesh absolutely won't. We use this stuff at work for filters and it's incredibly free flowing. I used some in my KTM a while back and when I stripped the exhaust to repack it, which it didn't need, the mesh was completely clear, if discoloured.

Pictures below showing the finished job as the image above makes the end cap look huge and in reality it looks fine.