Popping on over run

[pencil shavings]

When I first got my bike, 03 SV650S, it would pop and crackle really nicly on the over run at about 4500 revs. Now I only get a really small burble at about 3500, but no pops and bangs. Nothings been changed in terms of fuling, air in take or exhaust, no engine mods at all actually.
The exhaust is a straight though two bros race can.

Anyone got any ideas of things I could check or do to get my pops and bangs back!?

[G]

If there was a slight air leak at a joint, this can be a cause of poping and banging of an exhaust system.

Over time the slight leak may be subjected to a build up of carbon deposits and hence the hole would gradually become blocked, stopping or reducing poping and banging.

[pencil shavings]

I was thinking that it could be somthing along the lines of reduced air intake, but I thought it would more likley be down to the air filter than a gap in the joint.
If I put a free flowing air filter in would I be able to regain the popping on the over run? because it does sound the danglies!

[yorkie_chris]

You'd make it run really lean and burn things without remapping.

Does your pointy thing have PAIR system on?

[Smudge]

yep Chris ive still to disable mine and get a remap before i burn it out

[yorkie_chris]

It'll be right with just a can

The PAIR doesnt actually effect the mixture at all on normal running, it just burns any excess fuel on the overrun by admitting air

[Smudge]

yep i think its added after combustion

[ThEGr33k]

http://www.peterverdonedesigns.com/images/content/motorcycle/pair.jpg

As you can see, just after.

Your popping might be affected by temprature. I notice mine pops more in warm dry weather. I think it requires the exhaust to be really hot, so as the weather is cold then the exhaust will be cooler.

Just a guess though ;)

[pencil shavings]

thats a good point about the temperature. except i thought that cooler air was higher in O2 and i thought that was the crucial part in the bang and pop. are possibly the O2 content is higher but the exuast dosent heat up enough to make use of this?

has any one else experianced this?

[thor]

In cold weather air is denser you you get more oxygen for the same volume.

[yorkie_chris]

cooler air was higher in O2 and i thought that was the crucial part in the bang and pop.

In cold weather air is denser you you get more oxygen for the same volume.

Yup, the %age of O2 remains the same, colder air is generaly more dense.

So I would say that in cold weather the mix will be leaner, same volumetric flow, more mass flow for the same fuel.
So in hot weather there'll be a bit more fuel there to burn with the PAIR air and cause them bangs.

I'd remove the PAIR on general principle, its extra weight and complication that doesn't do much.

[Smudge]

you environment killer you, last night i started her up with some revs as i was in a tunnel and wanted to go rrooaarr but too much revs and she went rrooaar oooooo bang and a flame shot out lighting the tunnel up i thought i betta get out of hear cos it sounded like a gun shot lol

[ThEGr33k]

LMAO Smudge.

I think it is probably a mixture of several things, rest assured it is in no doubt all directly related to the temp. :smt023