What is smog?

[JamesC]

I am thinking about getting a KTM 350 EXC-F and everyone says you should remove the smog kit because it makes the bike pop, but what is a smog kit? What does it do?

[awayatc]

smog is American for smoke/exhaust gasses.
Vehicles there need to pass emission tests.
Not in NZ.

Not sure what KTM has added to reduce smog

[SMOKEU]

It'll be something that will strange the performance out of it for emissions.

[pete376403]

The KLR had a smog kit - its a vacuum operated valve that bleeds fresh air into the exhaust port when the throttle is shut, to complete the burning of any unburned hydrocarbons . As such it wouldn't have a great (if any) impact on performance.
In the US there are two models of bikes, California (extra smog gear) and "49 state" models (the rest of the country) which are more uncorked. I'm guessing the KLRs that come to NZ are 49 state versions.
The California models often recycle exhaust gas back into the inlet to reduce combustion temperature, which in turn reduces oxides of nitrogen in the exhaust, but also reduces power. The OPs KTM may be a California model (or KTM may not bother producing two different versions) Hence removing the smog equipment to get the power back

[tigertim20]

It'll be something that will strange the performance out of it for emissions.

not always dude.

also referred to as AIS, and a few other acronyms.

basically its a system that dumps clean air into the exhaust to balance out the emissions.

there are rules overseas that state that exhaust emissions must not exceed XX amount. Dumping clean air into the echaust system to pass emissions is a cheap shortcut (or loophole) in the system, much cheaper than building an engine that actually burns more cleanly.

with regards to the popping -what it will likely do is the clean air allows the unburnt fuel that gets dumped into the exhaust ignite and make a popping sound.

You can get smog / ais blockoff kits cheap as fuck (about $20 on ebay) and they are usually very very easy to fit with basic tools yourself

[pete376403]

$20? The air blockoff on the KLR was a 6mm screw into the exhaust port air connection. A good dollop of Loctite studlock to be on the safe side, capped the vacuum port at the carb and its all good.

[tigertim20]

$20? The air blockoff on the KLR was a 6mm screw into the exhaust port air connection. A good dollop of Loctite studlock to be on the safe side, capped the vacuum port at the carb and its all good.

depends on the bike. kits for R1's are around that mark - depends on how the system is done on each model. Could have done all my previous bikes for much less than $20 if Id fabbed something out of stuff that was laying around, just tidier to buy the Ebay kits as the look prettier when you're done!

[Waihou Thumper]

My KTM is a California model 2001. It originally came with a can underneath in the same place we would have a tool kit standard from factory.
It was connected to the air box and the fuel system. It was simply a vacuum pump for exactly as you say, to control emissions, fumes etc...
I have removed it with no detriment to the engine at all.
The early models that came into NZ were sometimes spec'd US/Canada as KTM back in 2001 wasn't as big here in New Zealand.
I rang the dealership it came from and they recalled selling these models.
It is 2001 with only 550 km on the dial, sure is tight and new....

[hayd3n]

i had to fab blanking plates for my hornet