I have an '06 XL 1200 C with 2800 miles on it and the only modification being the removal of the back shell of the air filter housing. When I'm sitting at an idle and give it throttle it backfires and spits, some times justonce and other times several back fires and spits,even to the point of the engine quitting. The engine also feels like it is hitting hard at an idle, one cylinder hitting with a sharp ignition of the fuel air mixture, and the engine will rock back and forth harder than before.

I have read the other threads about backfiring in this group but I cant believe that just removing the back shell of the air cleaner would cause the mixture to change that much.

I'm using a K&N filter and live at 1200 feet above sea level.

Your help in this matter is deeply appreciated.

 

removing a whole cover changes it alot. your running REALLY lean

why did u take it off? its not worth it

 

Sure Sounds on the lean side to me ....

 

By removing the back shell what are you meaning. It is my knowledge that it is needed to hold the carb in place against the intake manifold ensuring a tight fit. That is, unless you have an adapter of some kind.

 

The bike was already running lean when it came from the factory, you just made the problem worse. The solution is to rejet the carb.

 

[sm=chairshot.gif]> is needed to hold the carb in place against the intake manifold ensuring a tight fit < When I said "the only modification being the removal of the back shell of the air filter housing" I cut away the plastic around the mounting pad between the carb and the filter housing.

Will I need to have the bike dyno'd to find out what jets to use? [:@]

Thanks for your help.

 

You will likely be real close if you install a #45 pilot and #180 main jet.

 

Thanks I will give it a try.[sm=deal.gif]

 

[:-]Picked up the factory maintenance manual and it shows the Main jet to be a 185 jet and the slow jet to be a 42 jet.

So it looks like I will need to get a 190 Main jet and a 45 slow jet?

[IMG]local://upfiles/55053/1401FBD7A81D426F9BC08DF442EF6ED5.jpg[/IMG]

 

Leave the 185 high jet and change out the low to the 45. See how it runs with that first. The 190 might be a little too much. Besides, it's the low jet you want to change because all your problems seem to be from that area of the RPM range.For that matter, most folks are using 45/180.