KTM Owners Forum banner
  • Hey everyone! Enter your ride HERE to be a part of this month's Bike of the Month Challenge!

1 - 17 of 17 Posts

·
Registered
Joined
·
1,667 Posts
Discussion Starter #1
Upon stripping my carb for a clean I found the idle was only one turn???

The manual states 1.75 turns so I turned it out to 1.5 to test and found it now back fires alot more when I throttle off,...

Can anyone tell me why and if I should go to 1.75??

450 exc 08 - runs well on 1 turn and 1.5
 

·
Registered
Joined
·
3,643 Posts
might have this wrong but turning it out makes it richer i think. the backfiring is unburnt fuel igniting in the exhaust so if you made it richer there will be more fuel going out into the exhaust and therefor more backfires? make sense? ktms do tend to backfire as they exhaust is only a push fit and it draws in air that allows the fuel to ignite
 

·
Registered
Joined
·
1,667 Posts
Discussion Starter #5
Hi John, the bike did pop alot before but now it full on backfires like a gun!

Not to bothered and will try a few settings, just wandered if you ktm guru's had any words of infinite wisdom.

I am sure this is another of those subjects that keep getting repeated, but a search didn't turn much up.:frown:
 

·
Registered
Joined
·
3,643 Posts
did you check the float levels as that can make it go too rich too.
also the 'idle' as you call it is the mixture screw which is under the carb. the idle is the large black knob which just lifts the slide up slightly to raise or lower the revs.
did you set the revs at +/- 1200 and then adjust the mixture properly ie turn it one way and then the other to get the best idle?
also have you checked that the carb is sealing properly on the rubber intakes?
 

·
Registered
Joined
·
1,667 Posts
Discussion Starter #7
Oh while i'm on the carb subject, is it normal/compulsory to remove the sub frame each time you wanna remove the carb?
 

·
Registered
Joined
·
3,643 Posts
Oh while i'm on the carb subject, is it normal/compulsory to remove the sub frame each time you wanna remove the carb?
???????????????????!!!!!!!!!!!!! not on my 2005 model it isn't! see my re-build thread
 

·
Registered
Joined
·
1,667 Posts
Discussion Starter #9
I set the black knob to allow 1mm clearance as per manual and the lil mixture screw underneath to 1.5 turns out from 1 and gave it a good ol clean. I'll give the seals a good check tomorrow but quite sure they good.

As for the sub frame I can't seem to get the carb out without removing it. But I bet that's just me being a pleb.. (pig to do if you just wanna whip the carb out)
 

·
Registered
Joined
·
3,643 Posts
on my bike i just loosen the clips and swivel the carb in the rubbers (with tank off!).
You have to set the mixture screw while it's running to get it right. Set it a standard then while its running turn it in until the revs start to alter then do the same while turning it back out. Set point is in between where it idles best.
 

·
Registered
Joined
·
511 Posts
Dunno if it works on the newer models, but on my 05 you can remove end can, remove subframe lower bolts, loosen top bolts, loosen airbox to carb jubilee clip, then just swing the whole subframe up and over and out of the way. Takes 2 minutes.
 

·
Registered
Joined
·
3,643 Posts
did you set the idle as mentioned earlier?
 

·
Registered
Joined
·
1,667 Posts
Discussion Starter #14
No not yet, I have been given an order by the lady of the house not to touch my bike in any way till monday, as I must pack for our weekend away..:(

Can't complain really she lets me out 3 times a week and I work on the bike all the time. I will keep you posted mon/tue
 

·
Registered
Joined
·
1,667 Posts
Discussion Starter #15
also have you checked that the carb is sealing properly on the rubber intakes?
Can't believe it!!! I just got back off holiday and have done the suggested checks on the carb. Starting with the airbox intake rubber - It was completely undone....:wanker:

Glad I checked that 1st... It seems fine now so I will go for a run tonight and check it out..:rolleyes:

Do you think I have done any harm - It only did one 2hr run green laning in damp conditions:confused:
 
1 - 17 of 17 Posts
Top