Background:
I just bought this bike, and I had an issue where it would stall once the engine warmed up and it would sputter when I was aggressive on the throttle in 3rd or 4th gear. I took the bike to a local shop and the technician checked electrical connections, changed the battery, changed the air cleaner filter, and cleaned the IAC. Now the bike no longer stalls at idle but now it will sputter at times when taking off in first gear, backfires, and idles very low.

Mods:
1550cc big bore kit
Upgraded cams (unsure of specifics)
True dual exhaust
Power Commander III usb

Any assistance is solving this issue would be greatly appreciated!

 

Check fuel pressure , could be a plugged fuel filter or pin hole / break in the fuel line inside the tank .

Any codes come up ?

 

How can I check fuel pressure? Wouldn’t fuel pressure cause an issue no matter the engine temp?

I believe the only codes were for the battery and the blinkers. (LED’s installed without load equalizer)

 

You would have to get your hands on pressure tester or take it in to have done , just to rule out a fuel issue . Good point , if your bike runs and ride great until it warms up , then starts acting funny then it's possible it may not be a fuel issue . How many miles on the bike ? if the fuel filter hasn't been changed for awhile it's probably due for one .

Could be a temp sensor acting up also , they are known for not throwing a code when they start going . No way of testing it either , that I know of , but cheap enough to replace .
Map sensor , check connection and clean with sensor clean .

You may want to try cleaning the IAC again and see if it improves , if it's still the original one it's possible that's its just simply tired and needs to be replaced . Take a rag and place it inside the throttle body and spray it down with some cleaner , check the butterfly as well and make sure it's clean and shiny , no carbon build up around the seat when closed .

Other things you might want to do , is check voltage at idle and at 2000 rpm , just to rule out low voltage . At 2000 rpm you should be reading 14v + , but nothing over 15v . I have seen voltage regulars fail when they get hot , worth a check .

Go through all your connections , connectors , fuses , relays etc and check them for corrosion , use an electrical contact cleaner on them . I've learned over the years , corrosion can cause all sorts of hard to find issues .

I don't know much about your PC3 , but possible that it could be a tuning issue . You could contact the dealer and see if they have an updated map or have any suggestions .

 

I cleaned up the throttle body quite a bit. In doing this I realized that I could see quite a bit of what I assume is carbon build up on the front cylinder side of the throttle body. On the rear cylinder side it was totally clean.

I assume this is not normal.

Any idea what this might be?

 

The only only thing I can think of is that there might be a intake seal leak on the rear cylinder , which would possibly make the front run richer ( PC3 Tuning ) . Remove your plugs and compare them , guessing the front one is going to be a lot darker . Post pics of plug if you can . You would have to check for intake seal leaks , very possible with an older bike .

Maybe someone here will chime in and elaborate on this , a little beyond my expertise ...

 

UPDATE:

I brought the bike back to the shop to have any possible codes pulled. There were no codes even though the check engine light came on the night before.

The temperature sensor values appeared to be reading normal values.

I replaced the IAC with no noticeable change.

I am starting to think this may be a tuning issue. Any other recommendations would be greatly appreciated.

 

Confirm your fuel pressure is in spec before you go chasing your tail.
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