Added this to the local Toronto boards, but worth sharing again I hope. Without a muffler of some sort it really is just a tip on a straight pipe. Might be ok for a v-twin or a inline four, but its a bit much on a parallel twin 250.

Its not a DIY so I put it in the farkles section. If you plan to do something similiar you can PM or post here if you have questions.

Enjoy!

From the original post + some editing:

I have received a lot of questions about the exhaust set-up on my 250R, so I figured I would share. Thankfully the comments are mostly positive after the latest addition of a chamber that actually trims the sound level

The original custom exhaust I made was this guy; A custom old school yosh (probably older than me) mated to the factory header:

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/7bf48fa0.jpg

Then I saw the gixxer setup on Kawi-forums and loved the look. The near finished and then finally finished pics:

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1169.jpg

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1171.jpg

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1173.jpg

This is whats inside of the muffler

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1196.jpg

All done

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1184.jpg


http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1185.jpg

I liked the look and the challenge of a custom exhaust setup. It was a fun project but time consuming. Until an actual chamber was built, the exhaust was also too loud to bear. At that point it was a straight pipe with a tip on it.

I made a chamber was made using 1 3/8" tube and 0.080" sheet steel to make a "pancake" style muffler. Then I used 1 3/8" perf tube wrapped with steel wool. The steel wool I bought is intended for muffler use and not for cleaning pots and pans... i doubt there is any difference but it was easier to work with.

The geometry of the actual muffler is far (very very far) from ideal, since the perf core is adjacent to the upper wall of the muffler body. Very little packing material fits in this area. In this case there was no physical space to build it any other way, and rotating the flat face of the muffler to be parallel to the ground would cause ground clearance issues. If you look at the photos I actually had to press the chamber in at certain spots to clear the right fairing. Nothing some round stock, a bf hammer, and some heat couldn't take care of.

To make this bad boy fit, a lot of changes we made to the factory header. Some patience, and the "measure twice, cut once" motto were followed. When it was all said and done, some high heat manifold paint and fresh exhaust gaskets were the name of the game.

Overall the sound is good. It’s louder and deeper than stock, and different from the many other 250R’s with slip-ons. Going forward, Im not sure I would do it again during the riding season, it too away time that could otherwise be spend on the bike.

Nice work!

Very nice. I like the idea of improving the looks, but keeping it relatively quiet. I'm guessing there was no way to turn the muffler so it sat flat to the bottom of the bike.

nice job.

how's the high temp paint holding up? we built some custom exhausts for our xr100 race bikes and it always cooked the high temp paint off.

Thanks for the complements guys!

Camaro: Turning the muffler sideways is probably possible but a tremendous amount of work. The cooling fins on the oil filter housing require either a compromise on ground clearance, or a lot of painfully slow custom work to just skirt around the bottom of the engine. You will also have to trim the fairings to make it fit, or again some crazy geometry work to make it fit.

Here is another pic to show you just how tight it is.

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1188.jpg

http://i385.photobucket.com/albums/oo291/np6000/Ninja%20250R/IMG_1193.jpg

Putting it below the oil filter housing makes it the lowest point on the bike. The way I set it up, the bell crank for the rear shock is the lowest point.

Broom: I have used VHT High temp flame proof paint. They have two, I use the one rated for a higher temperature. Holds up quite well, provided you have the right surface finish and its (very) clean before you shoot paint. If you look at the photos I ran out of paint and used tremclam flat black on the gasket side of the Gixxer tip. You can see its discoloured to a silvery blue and keeps getting worse with time. I need to repaint it.

ahh... i think i was just using BBQ paint... haha

I see the tight clearances now. Maybe if you decide to keep messing with the design you could look into a bullet muffler design, though as you said there isn't very much room to mess with.

I see the tight clearances now. Maybe if you decide to keep messing with the design you could look into a bullet muffler design, though as you said there isn't very much room to mess with.

Whats a bullet muffler design?

If I were to change anything I would try to make this: The coned perf tube within a perf tube. Probably increases back pressure a tad, but would make things even quieter. Also kinda tricky to hand fab.

A straight through design. Probably wouldn't make it any quieter (in fact most likely a bit louder), but might fit up inside the fairings.

Something like this (maybe they only call cats shaped like this bullet)
http://www.summitracing.com/parts/JEX-A3009B/