Yamaha XT660 R

c-m · World Chat Champion Joined: 12 May 2006 Karma :

Am I missing something here?

Isn't the XT660 R a single cylinder bike making about 45bhp?

If that's the case, why in every picture i've seen of it, does it have twin exhausts with two sets of downpipes coming from the engine?
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yen_powell · World Chat Champion Joined: 22 Jun 2008 Karma :

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Plenty of singles, including low powered ones, have twin exhausts outlets.
I presume it's something to do with speed of gas flow from the outlet valves.

P. · Red Rocket Joined: 14 Feb 2008 Karma :

600cc single, 2 outlets.

https://yesterdaystheory.pwp.blueyonder.co.uk/TT600R2.jpg

Fizzer Thou · World Chat Champion Joined: 06 Aug 2011 Karma :

G · The Voice of Reason Joined: 02 Feb 2002 Karma :

Good point! I did 'know' that, but was thinking of my KTM and forgetting it had a different type of frame (the exhaust port is still angled a bit).

Fizzer Thou · World Chat Champion Joined: 06 Aug 2011 Karma :

My KTM450RFS has twin exhaust ports

https://i666.photobucket.com/albums/vv23/WiNot_Rhencullen/Workshop/Picture212.jpg

but is joined at the nearest point to the cylinder head so that KTM were able to narrow the twin downtubes of the frame accordindgly.The older KTM400RFS bikes c.2002 had twin header pipes that joined just before the secondary length.I seem to remember reading that KTM found that twin downpipes had less gasflow than a single,hence the switch c.2004.
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