back firing when starting up

[smartbike11]

morning
hope you all had a fantastic xmas, and are enjoying being back at work!!!!!.
I need to pick some brains, i have currently got an 03 600 hornet, when i start her up in the morning she sometimes backfires(yesterday was really quite loud), it happens even when starting up with the choque on and the choque off, i dont work far from home about 5 miles so its not getting a really good run to clear it out. any ideas waht might be causing this, i have cleaned out the spark plugs and changed the oil?, it is due for a service next month, also whether or not it makes a difference, there is an aftermarket scorpion end can fitted, any help would be gratefully
recieved
chris

[Jon B]

Could be running a bit rich maybe.

[chris_1127]

what jon said - look for black sooty plugs after its been ticking over for a while to indicate this. check that the air filters not clogged too.

If its not the filter, and its running ok thoughout the rest of the rev range it could be the exhaust - although from memory when i put an aftermarket exhaust on my gsxr i had to richen it up a bit not lean it out.
if its just at the lower end of the rev range you may just need to play with your pilot mixture to accomodate for the freer flowing can

[Funky]

Use redex when you fill up your tank, about 1 in every 3 times, it'll help clean your system through.

[billinom8s]

good tip funky

[smartbike11]

cheers guys,
it runs fine, once its started its just when it fires up initially?

[Mike Daytona600]

Use redex when you fill up your tank, about 1 in every 3 times, it'll help clean your system through.

We use some stuff by Silcolene called Pro FST. It's about a tenner for a litre but will last you ages. Works really well.

If you're only doing 5 mile journys the first thing you should do is the cheapest and most fun option. Take it for a f'ing good blast to clear out the cobwebs. Get it nice and warm. If still happening after that tell them when you take it for a service.