Kawasaki Sportsbike Riders Club - Australia - Online Forum

I had a yoshimura slip on for my 2010 250r a while ago and it backfired occasionally on start up.Quite loud when it did it too.Thinking about putting it back on but would like to solve the issue first before i go terrifying the neighbors at 5 in the morning . I asked at Flywheels whether it needed jetting and they said only really if you go the full system not just a slip on.
Does any one have any ideas on causes and cures?Is the backfire one blow away from damaging something?
I've been running the stock can for ages now but the Yoshi really does look nice on the bike.I know it sounds like a WRX cross lawnmower but the stock can sounds like a sewing machine.

it leans out any bike with a better flowing exhaust.when does it back fire?on a back off.

Only on startups.Not every time though.

sounds lean to me webcase do you youse the chock?or cold start.

to me it sounds like the idle circuit is lean best to check it out with a AFR unit

She's a choke start.It doesn't go otherwise in the mornings.It did it without the choke also of an afternoon every now and then also.Its one of those things where it wasn't every day or all the time but odds on to be in the silence of 5 am "" BANG !!!!!""
Could it be as simple as adjusting the mixtures?Whats an AFR unit?

If it's just a slip on it's cool. It's a 250 so jetting won't get you much. Don't rev it when you start it and you'll be fine

i had the same thing with mine when starting it cold without choke...... it has never done it while tho choke is on during start up....... However i have an akrapovic slip-on, not a yoshi..... however i had the exact same thing with mine on cold starts..... but only when i had the choke off...... does sound awesome when it crackles n pops when down-shifting though.... =P

Ive got a screaming demon slip on and very rarely i get the backfire at cold/ warm startup ONLY because ive givven the bike a bit of throttle before starting it up... ive started to think that because of the reason of no electronics and carby, the vaccuum sucks a bit too much fuel at the startup it goes BANG!! thats just my opinion, i cant be 100% on the issue because im no mechanic lol!

and in saying that i always get backfire when using the engine brake... love the noise but i havent noticed it doing any harm to my bike at all Hope this helps!

Have you altered anything else along with the slip on?Airbox mod or replaced it with a K&N filter kind of thing?Would adding one make it worse??
I'm probably being a bit of a nana about it.I do all kinds of crap to my car and don't blink but since i've bought this bike i'm scared to touch the damn thing

my bike is as stock as they come other than the slip-on and a couple of cosmetic things... not jetted,no K&N filter, no airbox mod...stock as a rock, and sheruns quite well
Are u on ur P's/ L's?

I'm on my P's.Bout a month to go till blacks.Had the bike for nearly a year and half.Had the pipe for a while but just haven't run it for a few months as the backfire was giving me the shits.
I'm not looking to add anything ($$$)to the bike to get anything more out of it hp performance wise,just trying to make sure the backfire isn't damaging anything.But i really like the look of the slip on over the stock can and if there was an easy fix for it.

First things first, have you made 100% sure that there's not an airlink between the linkpipe and the muffler, etc ?

they do backfire every now and then mate, my zx6r does every now and then too, nothing to worry about!

Six Addict wrote:they do backfire every now and then mate, my zx6r does every now and then too, nothing to worry about!

Glad i'm not the only one.

mike-s wrote:First things first, have you made 100% sure that there's not an airlink between the linkpipe and the muffler, etc ?

Now that you mention that.On the standard can it has like a sealant tape of sorts on the connecting tail that connects to the headers.Looks like the old muffler bandage stuff.The Yoshi didn't come with any and i never really thought it would need it being such a straight through unit.(Basically a can with a bit of rolled mesh in it.)
I'll throw it back on and see how it goes.
Thanks for the help guys.Much appreciated