[prestonlaw]

I will start with my bike and then move onto the problem...

2005 Ninja 250 with 13,500mi
Muzzy Exhaust / K&N Pods / Jet Kit / Denso Iridium Plugs / 8.8mm Pro Wire Set

With all of the above installed at 3,500 Miles I decided it was time for some basic maintenance

I re-charged my K&N Filters, re-packed my Muzzy Exhaust, swapped out my Denso Iridium Plugs w/ the same, and put in a new battery.

I then fired up the bike, it idles and rev's fine, drive it down the road and it accelerates just fine, but then when maintaining speed or decellerating the bike runs rough and wants to backfire. I had this same problem when I installed the filters/exhaust/jet-kit back at the 3,500 mile point, but I lifted the needle and it was running perfectly for the past 10k, now a simple tune-up and it's back to square one? Doesn't make much sense because everything is the same as before?

Any ideas on where I should start? I really don't want to tear apart my carb and do any adjusting, hoping for a simple fix or an idea that I didn't think of, I'm running the same parts as before?

Note: Choke is not stuck, and this is at regular temp. If I put the choke on it seems to run a hair better but still not right.

And here are a couple small pics of the bike so you can see what I'm working on...

[Wheels]

Thanks for posting stats about your bike
To start did you do valve adjustment between 3500 and 13500? If you haven't taken the carbs apart since then that could be another issue besides...

Wait wasn't someone making a problem form page with radio buttons, automated problem check list.. anyone. .. .

Tighten bolts check intake/exhaust leaks and shout at it when it is bad, tough love

[prestonlaw]

I actually have never done a valve adjustment on this bike and I have owned it since day one - I checked it once but they were not out of spec...don't think that's the problem since it was running just fine the day before the maintenance...no exhaust leaks, no intake leaks ->

Could some crap have gotten into the carbs and cause a problem like this while the filters were off the bike? I did have the filters off overnight and did not cover the intake on the carbs

[pyr0boy]

While I haven't had exactly the same problems as your are now, and wish I had all those sexy shiny parts , I can suggest somethings.

Intake manifold shot (behind the carbi black tube thing)
Head Gasket (Compression Test Time)
Unclean Fuel clogging up your nice jets

I think valve timing is a possible problem, although they would have to be a GIANT step out to make this happen.

Hope this helps.
----
Pyr0

[dwkfym1]

I got a dumb theory for you. Maybe your valves were causing a lean condition which was mitigated by your dirty filter and an exhaust that needed repacking. And now that you have cleaned out your filter and repacked the exhaust, the original airflow is back and your valves are still promoting a rich condition. The way to make sure would be to do an adjustment. What do you think? I think worth looking into if you got an extra 2-3 hours around..

[autocracy]

[Hexfactor]

I don't know about the lean condition, but that is one clean bike! The exhaust is very nice and i like the chain guard too! Very nice.