nope just take the cat out as below. to get it working almost like a race pipe you can do as i did below. nice flow in the gas and keeps the std look ;)



http://i92.photobucket.com/albums/l3...e/P1010206.jpg
http://i92.photobucket.com/albums/l3...e/P1010207.jpg
http://i92.photobucket.com/albums/l3...e/P1010210.jpg
http://i92.photobucket.com/albums/l3...e/P1010211.jpg
http://i92.photobucket.com/albums/l3...e/P1010212.jpg
http://i92.photobucket.com/albums/l3...e/P1010213.jpg
http://i92.photobucket.com/albums/l3...e/P1010214.jpg
http://i92.photobucket.com/albums/l3...e/P1010215.jpg

the holesaw goes down the end pipe. i pressurised it to make sure the welds were air tight - not that easy as it turned out - hence the thicker welds. i normally weld much nicer than that !

Great! Thank you very much
Only one last question: with the new holes, noise increse to much?

Thank's again

Not as loud as a race system. But is a bit noisy for 5am starts! Not as loud as my ktm exc and that has a FIM legal enduro can fitted. In traffic you'll not stand out too much so as to get pulled by police. With the fuel mod and filter ( snorkle removed) you'll get better fuel economy and pulls better.

Thank's for all your support!
I've just posted pictures and comments on an Italian forum ( www.clubtenereitalia.it), I hope this isn't a problem (I refer all my post to xt660.com, not as my personal)

no that is fine. i've done a in review of the xt660z in the latest Adventure Bike Magazine as well. i'm going to post that on my own website ( www.redbikejohn.com) once the mags are off the shelves in the stores. this on-line version will be much much longer and in depth compared the magazine one as i was restricked to a small word count.

Exhaust rattle
 

My 660 z has got 14 miles on the clock and the exhaust rattles when you roll off the throttle even just revving it up in the garage.
Reading this thread it sounds like there is a possibility of the CAT coming loose in the can.
Is this correct and if so is it a warranty job?

I did a similar de canning job on my old KTM duke but I ground off the weld seam right round and removed all the tortuous plating inside the can and got an almost straight through route for the gas. I then TIG welded the seems back up and you couldnt tell anyone had even been in there. The can lost about 3 kilos in the process.
It Made a lot of difference to the performance but the fuelling remained ok.

This is how my cat came out:

http://www.mijnalbum.nl/Foto-RU86HYFE.jpg

... at least, I suspect it is the cat (btw. that's cm's, not inches)

Toss it, put on a aftermarket piece: looks better, less weight.

HJ

if the rattle is from the rear then yes its most likely the cat but if its from the front is could be the inner skin of the downpipe that has seperated from the outer - that is if yamaha fitted a double skinned pipe to the bike, they mostly do.

Hi, and thanks for an excellent write-up in cat removal. Its done, and the engine feels better, more willing. :applause:
Only regret is that I used the hole-saw aswell... Its too loud for my taste. Cool to begin with, but after som miles I get tired and its a pain in my ears.
Maby not the volume itself, but the sound is pretty "hard", not that nice deep thumping I was hoping to get.

Do I have to re-open it and weld the holes shut, or do you think its possible to use rubber plugs or something in there?

Ill probably get a single can one day, but Id like to make a fix for now..

Osmund