Hello XT forum.

I have a new to me 2013 XT660X that is completely stock and has gone 7800km.

However, the exhaust is popping like crazy especially when slowing down. Is this normal or is it possible that there is something wrong? I dont remember my old KLX250 having this problem.

Thanks

My standard 660z pops like corn in the microwave

TADTS

Blocking the AIS pipe reduced the popping on my Tenere, it's worth trying.
http://www.xt660.com/showthread.php?t=5544

Don't close the throttle completely. I think its the unburned fuel escaping.

The popping and backfiring is perfectly normal. It is (as Jaques says) unburnt fuel igniting in the exhaust when the throttle is snapped shut.

On older bikes (with carbs) like your KLX the fuel wouldn't ignite (unless you had a leaky head/downpipe gasket) as it is starved of oxygen and would just pass out into the atmosphere unnoticed. Current emission regs mean that unburnt hydrocarbons in exhaust gases are a big no no, so air is deliberately introduced to the exhaust port downstream of the exhaust valves to make sure any excess fuel is ignited and burnt off.

On the XT this is known as AIS (Air Induction System) and an ECU controlled valve opens to let air into the exhaust from the airbox to burn off excess fuel when the throttle is suddenly closed. It also opens on a cold start to clean things up as the engine runs rich, and also to speed up the warm-up process as the head, exhaust ports and system will get hotter quicker because of the fuel igniting in them.

AIS is important if you have cats fitted (stock exhaust system) as unburnt fuel quickly damages the catalyst.

If you don't like the popping effect of the AIS (and you don't have cats) then you can simply block or clamp the pipe to the AIS valve that runs from the airbox (or remove the whole system altogether). You cannot just unplug the AIS valve under the tank as its default position is 'open' and the bike will pop and bang all the time!

__________________

I blocked mine for Dyno testing (messes with the test results) but then unblocked it the other day.

Shotgun!

__________________
Bike: 2013 XT660Z, TKC70 tyres

Mods:
Barkbusters, Scottoiler, DIY Tail Mod, DNA Stage 3, Power Commander V & O2 Eliminator, Exan X-Black Stainless exhaust, Tool tube, Ohlins linear front fork springs, Nitron rear shock, JT front and Supersprox rear sprockets, D.I.D. VX 520 chain, Adventure Spec bashplate, DIY USB Outlet, DIY chain guide, Kev's Throttle mod

http://www.facebook.com/onemooseonemotorbike

If you block the AIS, the catalyst will get damaged by the unburnt fuel.

However, in most countries motorcycle emissions are not tested, so you can block it and it doesn't matter if it gets ruined or not. It is up to you. If you don't like the popping then block the AIS - the bike will run fine. Just bear in mind that the catalysts may not work as well, if at all as time passes.

__________________

Yeah I know in Denmark where I am from they dont test ****. I was riding a big bore KLX with all emission stuff removed and no one gave a ****.

However, I have now moved to Germany and they are more strict here and I am not 100% certain what they test for so I will keep it all stock for now. I was more worried that there was some kind of issue with the bike, but since this is apparantly is fairly normal I wont bother doing anything.

Thank you all for your feedback.

This is why, although you can block the AIS with the stock system, it is always worth mentioning the effect on emissions and the catalyst. In some countries, and I'm pretty sure Germany is one (Switzerland is another), your bike will fail it's roadworthiness test with the AIS disconnected or blanked off and a non-functioning cat. Always worth checking your country's specific regulations before doing some mods - they aren't all the same.

In the UK, like Denmark, no ones cares about motorcycle emissions once the bike has passed initial type approval, unlike with cars and commercials. Emissions testing for motorcycles is on the cards for all EU countries in the near future...

__________________