heh, aye, nice pic - I think I get the gist of your explanation re. the unburnt gases.
:)

Thanks,

Alex.

If you like the popping with standard pipes, wait until you fit a pair of :CCC: cans. :deathmetal[1]:

The popping is due to excess air in the exhaust, either through leaks or more probably the Air Intake System that Yamaha have fitted in an attempt to clean up the exhaust gases for emission tests.

Not sure about CaptMoto's explanation, a twin is really two singles joined together. Assuming each has it's own carb and exhaust pipe, the combustion chambers are independent and so it does not matter if one piston is up when the other is down, each one still fires once every two revolutions.

When the throttle is closed at high revs, the rear wheel is driving the piston up and down. Very little fuel is getting into the cylinder, but it is still sucking in vast quantities of air. I would guess this causes a very weak air/fuel mixture, but can't figure why this causes popping.

Unburnt fuel in the exhaust can ignite when it hits a hot surface and causes a backfire, this is usually due to an over rich mixture, not what we have with the XT.

As Capt says, maybe someone more knowlegeable can explain what is going on.

RedDog, i take it you recommend the Carbon Can Co pipes then? Can you simply stick them on without doing anything to the fuelling/airbox?

Phew
 

I'm just glad to learn its the bike making that noise i thought for a while it was me. was gonna go and show my ass to a doctor.:sad11:

Ukiboy, oops just noticed this is the XTZ section. Don't think CCC do cans for the XTZ yet.

But yes, If you have an X or R I would recommend them. They look good and sound even better.
Had a lot of popping for the first few days but it more than halved after I tightened the clamps again, which confirms the air leak theory.
I increased the CO reading from 25 to 30.
http://www.xt660.com/gallery/display...ls%20fitted%22