WB Carbon Pro 2 Exhaust Problems

Guys i have fitted a White Brothers Carbon Pro II system to my 2007 YZF 450 but i'm having problems with it. I haven't had the bike to the track yet as i'm not sure if i will pass the noise tests with the problem i'm having

Anyway i have started the bike on the stand and its popping and banging real bad. It will pop when you open the throttle and spit a flame out of the tail pipe and the same when you shut off the throttle and the header pipe seems to warm up and glow much quicker on this system than any other pipes i have had fitted before? I know popping when you shut the throttle off is common but i have never had a bike that popped and flamed when you open the throttle?

I have spoken to a few people over here in the UK but nobody knows much about the WB systems so any help would be great. I have checked the seal where the header pipe meet the cylinder and that’s seems fine. I didn't fit the jet that came with the system as i guessed that they would be for the US market/weather so wouldn't be right for our nasty cold damp weather we get here in the UK. One bike shop did say it would just be down to contamination from manufacturing, things like release oil etc and metal filings inside being burnt off and that it should clear up and become quieter once the packing had loosened up a little??? does this sound right?

Any ideas where to start looking? what are symptoms of running lean? and running rich?

Thanks in advance and sorry about the long post :thumbsup:

Guys i have fitted a White Brothers Carbon Pro II system to my 2007 YZF 450 but i'm having problems with it. I haven't had the bike to the track yet as i'm not sure if i will pass the noise tests with the problem i'm having

Anyway i have started the bike on the stand and its popping and banging real bad. It will pop when you open the throttle and spit a flame out of the tail pipe and the same when you shut off the throttle and the header pipe seems to warm up and glow much quicker on this system than any other pipes i have had fitted before? I know popping when you shut the throttle off is common but i have never had a bike that popped and flamed when you open the throttle?

I have spoken to a few people over here in the UK but nobody knows much about the WB systems so any help would be great. I have checked the seal where the header pipe meet the cylinder and that’s seems fine. I didn't fit the jet that came with the system as i guessed that they would be for the US market/weather so wouldn't be right for our nasty cold damp weather we get here in the UK. One bike shop did say it would just be down to contamination from manufacturing, things like release oil etc and metal filings inside being burnt off and that it should clear up and become quieter once the packing had loosened up a little??? does this sound right?

Any ideas where to start looking? what are symptoms of running lean? and running rich?

Thanks in advance and sorry about the long post :thumbsup:

absolutely nothing wrong with the pipe....your jetting however is off and it is lean. Do not test jetting with bike on a stand. You must get the temp up.

You may have issues with passing the db sound test as these pipes are very loud.

Thanks for the reply, so i guess i need to look and see what main jet i have in there then try going up a size yeah? or will lifting the needle up one help?

The system came with a new jet but i didn't fit it as i thought it would be for US jetting so wouldn't be right here in the UK

Am i right in thinking that cold and damp means denser air so will need a bigger jet for more fuel yeah?

If i get the jetting right it will stop the popping and banging so will help with passing noise tests but does anyone know what level of noise this system is rated at?

Cold means denser air and the need for a bigger jet. Damp means the air contains less oxygen per pound (because it's been displaced by water) and the opposite.

Very cold temperatures tend to dry the air, also.

You don't want to necessarily want to change the main jet, but rather the pilot jet, as that deals with the fuel delivery from about idle to close to 1/4 - 1/2 throttle. You should go up one jet I think on the pilot and go from there.

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