Hey everyone....'07 roadstar with 17000 miles. I rode everyone of them and love this bike. Before 5000 miles, I removed the AIS, reworked exhaust to stage two and installed the K&N air filter. It soon developed a backfiring and coughing back through the carb that only happens after a period of short trips and a lot of setting in the garage. When I get it out after that, it will start and idle fine, but when I take off and it reaches mid range rpm under load, it will cough, sputter and backfire. If I hold the throttle at probably 3/4 open, it will continue this for quite a ways and slowly gain rpm until it reaches an rpm that will run smooth. If I shift up a gear, I go through the same thing. When I get to fourth gear, I hold it as wide open as it will run, it will cough and backfire and embarrass the hell out of me for a mile or so, then smooth out.
It will then run fantastic for the rest of the day, and on extended trips will run fine on the following days.
Only after I return home and let it set or make short runs up town for a few days, will it repeat this sputtering and backfire.
Inside the exhaust it is extremely black and carboned up, and I assumed it was probably running a bit rich and maybe the town driving was letting carbon build up in the cylinders, but I'm averaging 42 to 47 mpg on day trips which seems very good. Any ideas on what my next step should be. I thought I would need to rejet after the mods I made, but it just ran so good, I never went any further, and just yesterday, I took a 350 mile round trip with a couple of harley owners, and it ran so well (44.5 mpg) (better than the harleys) and I fell in love with the bike all over again.
Any suggestion appreciated.

Probably need to adjust your PMS a bit. Also our R* are very cold blooded it can take a good 3-5min for mine to warm up or it will do the same. You make want to run some seafoam in your tank too.

Steven

I am not a carb guy by anyone's definition, but is it still the stock jetting? If so it is probably rich. Have you tried running some seafoam in the gas to help clean up the carbon issues? I am sure the carb guys will want to know more. Removing the AIS should not have created any problems unless you have a leak somewhere. imo

Let me know what you come up with for a fix. Mine has just started doing the exact same thing. We are set up the same with the exception that I am at a stage 1 on my exhaust. If I down shift and punch it to get the RPMs really high, it seems to clear it up a bit. It doesn't happen every day, but it happens enough to make me rethink the AIS removal.

I can almost guarantee that the AIS removal will NOT cause backfiring only help reduce it. When you change the exhaust AND add new air cleaner you need to rejet. Stock jetting is normally rich anyways.

Steven

Check for exhaust leaks and tweak the PMS. If you have had the xhaust off it is a good bet you have a leak.

it really sounds like jetting since you did a K&N and the exhaust you have to rejet. Ais removeall will only help unless your block off plates are leaking which i doubt

when I take off and it reaches mid range rpm under load, it will cough, sputter and backfire. If I hold the throttle at probably 3/4 open, it will continue this for quite a ways and slowly gain rpm until it reaches an rpm that will run smooth. If I shift up a gear, I go through the same thing. When I get to fourth gear, I hold it as wide open as it will run, it will cough and backfire and embarrass the hell out of me for a mile or so, then smooth out.

This isn't the same as the decel backfire issue. It doesn't happen all the time for me. I ride every day and it has happened like 4 times in the past 3 weeks. Go to give her some throttle and she just coughs and sputters. It clears up after a while, but it shouldn't happen at all.

I'm not a carb guru by no means but have been adjusting my PMS as of late an I tried 2 turns out ran good but have popping on decel and cough on occasion. Keep adjusting out on PMS and 3 1/4 turns out and upped my idle speed and she runs great with no popping or cough. Don't know if I'm jetted correctly and not stock but if gas mileage doesn't suffer I believe I have found here sweet spot.

I would throw some Sea Foam into the gas tank and maybe spray Deep Creep or Carb cleaner into the carb throat (while running) to clean out any excess carbon build-up. Also, make sure your air filter is clean.

Determine that the bike is warmed up before you get concerned. Mine takes about a two minute running/driving onto the highway to warm up and then a 1/2 mile to get running good.

The hotter she gets, the hotter she gets!!


FYI - I bought used heads with only 2000 miles on them for a project (AIS removed). The combustion chambers & valves were pretty carboned up, especially the right side intake valve from each cylinder.