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Old 07-31-2012, 10:58 AM   #1
noob-saibot OP
Joined: Mar 2010
Oddometer: 27
Duke 2 bog at 3k

Hey My Duke 2 has developed an intermittent bog / hesitation a 3-3.5k rpm in first few gears (1/8 throttle ish). Doesn't always happen and when it does sometimes its just a stumble but sometimes it proper bogs and backfires. Powering through usually can be done if I can but doesn't always help and slipping the clutch can be required till i'm past 3.5k as I do plenty of city commuting riding. Don't understand what could be causing it when its being so intermittent. For instance on the way home from work it was not present at all whereas this morning it was very much present but seem to also go after a few miles which can often be the case when it is there.

Was up on dyno just a few weeks before it started and running clean and smooth as you like with nothing showing. Bst has all the usual mods done. Air / fuel screw adjustments make no difference to it. New plug too. No off idle stumble, as is bst's norm and no bog when free revved. Drained some fuel the other day and there was a tiny bit of water in it but nowhere near enough to do this I reckon. Have been through a few tanks aswell at this stage with some ethanol in once or twice to burn any off. One thing to note is once a few tanks back I let it get to the reserve time and when I switched over it got really really bad, backfiring a lot and eventually died. Switched back to normal and eventually it started and just about got home. Haven't let it get to reserve time since.

Any idea's? I know, I know look at bible and open the carb up etc but would like to see if anyone can pin it down based on the above randomness before anything is done. Surely if it was blocked jets or bad float it would be constant and not weirdly intermittent all round
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Old 07-31-2012, 11:22 PM   #2
Joined: Jul 2005
Location: Traveler
Oddometer: 5,194
Is the carb loose?. Screw the plug cap on tight.

Is your needle/needle valve worn out?
'02 KTM 640 Adventure-lowered
"On the road there are no special cases."
Cormack McCarthy-The Crossing

The faster it goes the faster it breaks.
And high performance=high maintenance.
Bill Shockley
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Old 08-01-2012, 01:20 AM   #3
noob-saibot OP
Joined: Mar 2010
Oddometer: 27
Originally Posted by bmwktmbill View Post
Is the carb loose?. Screw the plug cap on tight.

Is your needle/needle valve worn out?
Carb is secure and needle / needle valve / diaphram were fine last time I moved the needle clip - maybe 6 months to a year ago. Needle was smooth with no sign of grooving.
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