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

it might be possible to put some sort of expanding plug in but don't go for rubber as it'll only melt. the sound seems loud at first as the OE one is so quite. forget the single can. i just bought a MTC single can and they are LOUD, even with the bd killer in. no way are they below the legal limit.

you can have it for �100 if you like. stainless round can. all complete with link pipe and brackets.

Decatting the exhaust
 

Ive just decatted my standard exhaust as per the instructions here.
Ive gone a bit further as I did a couple of other things as well.
When I cut the cat out I decided to also cut out the pea shooter pipes on the other end. I was surprised at the difficult route the exhaust gases have to take to get out of the pipe. theres more restrictions in the other side of the box as well.
Anyway using a 40mm hole saw I cut round both pipes and snapped off the tack weld on the end of the perforated pipes, then I pulled out the 2 restrictive tubes.
I then welded on some 32mm stainless steel perforated tubing, stuck it out of the end of the silencer and then welded in some plates and a couple of bits of tubing just to finish it all off. I blocked off the AIS pipe in the air box to stop the popping.
End result, lovely sound which isnt to noisy, engine definitely breathes a lot better low down, I dont think its upset the fuelling and it still looks stock except for the larger bore pipes on the end.
I will post some photos tommorrow.

Sounds a good mod lets see pics.:typing[1]:

Can someone remind me how to attach photos

Use photobucket

You need to host the image on the web somewhere first as Wide suggests (like Photobucket, Flickr or something similar) then use a direct link to that hosted image from your post in the forum.

Create an account on an image hosting site (if you haven't already got one).

Upload photos.

Find the photo you want to use.

Copy the direct link for the photo from the image hosting site (easy on Photobucket as this is one of the options under the image in your album).

When writing your post click the �insert image� button on the tool bar, paste in the copied direct link back to the hosted image and you're good to go!

Have just started a decat. Would love to see some photos of the new exit pipes.
If u struggling email them to me and I will post them up :-)

Is it necessary to change anything else on the bike after this change, mapping, etc?
Got a spare exhaust, going to do the same and compare

What is the option of cutting off the pipe, remove the cat through the hole from the back side en re weld the pipe?

http://i806.photobucket.com/albums/y...2013/Decat.jpg

You would have to make a huge hole! The cat is twice the diameter of the hole.

http://i660.photobucket.com/albums/u...eden/002V2.jpg

http://i660.photobucket.com/albums/u...eden/001V1.jpg

http://i660.photobucket.com/albums/u...eden/003V1.jpg

i will try to do a diagram tonight to show where I did the cuts.
I put a large cut in both sides of the silencer just after the inlet pipe using a nine inch grinder.
This gives you another weld to do but means you can hacksaw out the last of the cat easily as it strongly welded in.
There is a central baffle plate that separates the inlet chamber with the cat in it and the outlet chamber with the two baffles in it.
If I was doing another pipe I would remove the whole upper section of the exhaust in one go as this would give you better access to the whole of the box for not much more welding.

looks a great job... how is the sound/tone of exhaust now

decatt
 

The sound is good, not that loud but it now sounds like a big single rather than a neutered cat. You have to do the AIS mod or it pops like hell on the over run.

Well done the pics of the way you cut it will be helpfull if I try and take the same route, cheers

Looks a good job mate.:bravo:

nice job! good write up, thanks.

Random question about your R&G tail tidy.....

Are both those lights brake and tail lights...or is one just a tail light and one just a brake light? Also do they come away from the black backing plate easily? (just screwed on?)

cheers

Hello, Yes both units are both tail light and brake light.
The LED assemblies are attached by a couple of 3mm screws but there a bit crap and corrode up easily.
One complaint I have had with the R&G tail Tidy is that the LED's point up to the sky and if your following you dont really see when the brake light comes on. I will stick a bit of packing behind the lights when I get a chance, to 'dip' them a bit.
The R&G is definately a lot lighter than the stock unit which weighs a lot. Im not that keen on the shape of the lights and have seen some good modified tail units on this forum.
Still doing the sketch of the exhaust and will post it this weekend.

Decatt the exhaust
 

Ive attached my drawing of the exhaust internals. Please excuse the quality but I need to sharpen my crayons.
Hope it give you an idea of whats where and which bits to cut out.
My mates got an XTZ and If he wants his pipe done I will get a photographic diary whilst doing it as it makes a lot more sense.
The perforated tubing used in the baffles was supplied by the excellent folk at PJ Engineering (1 &1/4 inch stainless steel)
the also supplied the outer tubing which fits over the performated tubing perfectly and finishes off the out side of the pipes really nice.
Happy welding!

http://i660.photobucket.com/albums/u...sieden/IMG.jpg

Also started on mine today

http://i806.photobucket.com/albums/y...013/DeKat3.jpg

http://i806.photobucket.com/albums/y...013/DeKat4.jpg

Monday the welding will be done

Put it back on the bike today
Disappointed, it's like the grump is gone, hollow empty noise ???

oh dear thats a bit dissapointing
Ok so whats the general opinion on de catting the standard exhaust ?? Sound wise I mean

Looking at the pic it looks like you left some of the side bits in situe so the sound might be bouncing around at bit. When I took mine out and cut the extra holes it performs better and doesn't sound to bad at all. I think I put price on this thread earlier but if not check on my website for the review. It has step by step photos.

I made a long drill bit and through the tail pipes and the baffle pate into the cat rattled it around to cut out the cat.gose well sound great.:SPanikengun77:

Basic decat done, haven't expanded tail pipes, yet!!
Sounds nice so onwards and upwards with the mods.

http://img.tapatalk.com/d/13/02/15/ryhyjy8a.jpg

Well just done mine with de cat courtesy of local stainless exhaust place and it does sound much nicer , will wait and see how the extra popping and banging goes but at the moment it brings a smile to my face. Ive done the same version as RedbikeJohn and I think its been for the better, especially at the mo I couldnt even contemplate forking out for expensive aftermarket cans

Can no one really record a sample of the sound of a de-cat stock exhaust?
Preaty please :)

hi there i am thinking of doing this mod, i just have 3 questions

1. how much louder is it now?

2. did you put the heat resistant wool back?

3. if you did put the wool back did you weld the mesh back in first then place the wool on top of the mesh and then weld the top on?

thank you!

As for sound....the De-cated zorst is louder than the standard, but not much really. Maybe has a little more bass to it but not much.

I dont have mine done but i have ridden behind a Ten with it done and its not totally obvious.

1. Not much
2.No. Dug everything out and put nothing back in.
3.N/A

thank you ime going to fire the cutinng tools/welder up next week ime also going to video it and make a before and after sound recording and put it up on youtube! :icon_wink: