Kawasaki Sportsbike Riders Club - Australia - Online Forum

My 01ZRX1200s back fires each time i back off or going down hill, i mentioned this to the mechanic when i put it in for its 12000k service he said it was because the external small tail pipe was removed by previous owner i have even changed premium fuels as suggested by owners manual any answers / suggestions

happened to my bike when i took the stock pipe off and replaced it (ninja 250) it only happened around 5750 rpm on trailing throttle.

dunno if the bike has a kleen air system (injects air into exhaust to burn already unburnt fuel) but this could be it... if so then maybe as the bike gets into a rich zone more unburnt petrol reaches the exhaust and hence gets burnt?? maybe im just speculating here... (IMO)

i wouldnt worry about it as it just makes the bike sound mean...

Thanks for quick reply my exhaust is all still original stock standard i have a feeling the service was not a complete one ? as requested but still i paid top dollar

bigdave58 wrote:he said it was because the external small tail pipe was removed by previous owner

i dont understand this.... u have stock pipe but the small pipe was removed??? other thing to do would be to tighten all bolts/nuts on the exhaust to stop air getting in that way....

again im just putting my idea out there... others may help

Perhaps mixture screws or carbies are out? Is it a carbied bike? Maybe you could take a pic to show us what you mean by the pipe removal you were talking about?

Is this the full on BANG! backfire, or the vrrrmmm pop pop pop type?

DaveGPz wrote:Is this the full on BANG! backfire, or the vrrrmmm pop pop pop type?

How bout the "POP" do I still have an airbox type???

1. Check header flanges for leaks.
2. Check mid pipe joint for leaks.

On stock systems , zorst backfires are usually caused by air leaks ie loose flange bolts / exhaust clamps etc... check it out and see how you go

if it's just a popping sound and not a mega loud bang thats just normal, most kwackas do it..it's the Kleen.

here is some info re removing kleen system which I think helps the popping ?? (insert member experience here)

http://www.ksrc-au.com/phpBB3/viewtopic.php?f=31&t=9175

also, you may want to put in dyno-jet kit to clean up your fueling, 16hp increase for less than $300. This may fix it also..

it is more of a popping noise not full on back fire, there is a small chrome pipe extention in centre at the end of tail pipe, you can just see it on lifeofcrimeguy reply (bike photo )this has been removed would this cause the problem it is a carbied bike the machanic said he checked carbies and all was good ?

My 9 and 10 did it also, 1 was carbied and other efi so hmmm but i think it is the carbs

G'day Bigdave58,

I also own a '02 ZRX1200S. These bikes run a emission exhaust system. The later ZRX's even have a catalytic convertor.

From your airbox to the top of the rocker cover you will see some rubber hoses some people call it a spider it goes into to plates attached to your r/cover under these plates are reed valves these valve allow clean air into all 4 exhaust ports to "clean" up your emissions. You can buy block off kits from a few places in the states (Muzzy, Ivan's) are a couple. You can also try richening up your idle mixture! I am not sure about your bike but some ZRX's idle mixture screws are capped and require a plug to be removed. Best done with carbs off bike. If you have no plugs then just check where your screws are set and wind them from base to approx 3 turns out and see how it goes. It is very normal for ZRX's to pop. I like it, On the dyno my beast on decel spits out about a 12" blue flame looks awesome!!!

Hope this explains the popping for you!!!