Hi. New here. Loads of great information here ppl.
Thanks a lot!

So, I bought mine used half a year ago (2014 orange/black model),
I'm a new biker so I had little to compare it with. Whatever the case,
the bike fits me pretty well and I really like it!

A few months ago and as I had to do a few minor repairs (broken
turn signal, some missing nuts at the rear fender side application
from a bad passenger seat fit up) the bike was left stored for 2
months and after fixing the above I decided to do an oil+new filter
maintenance. Following the manual's instructions I drained
it and poured *2 litters* of new 10w40 / jaso ma oil. Bike started
normally but I noticed that if, say, after 1 minute of idling (choke
closed by then) I opened the throttle so it will go BrrOOm, it will
stall after I release the throttle. Bike didn't do this before.

After a little inspection I found out the oil level was above full
(window completely covered) so I went and pored some on a
pan till I could be certain it was slightly bellow the F mark. Tried
to start again, no problems but the above symptom remained.

Thinking this would be an easy fix I though, maybe the spark
plug got covered in oil or smth, so I went and replaced it
with a new dpr8ea-9. This *almost* resolve the situation but it
would still stall sometimes if I do the same. When it does happen
it always happens in the same way:

start -> idling with choke open (20s) -> idling with choke halfway through (30s) -> idling with choke closed (1m) -> Sudden throttle opening by me (1s) -> throttle release (me again) -> bike back to idling for a fraction of a second -> bike stalls sometimes, if it doesn't stall it feels like its "right about to stall" for a fraction of a second (have seen the lights almost blink) but it will retake its normal idling.

One thing to note: The more I open the throttle in this sudden
motion, the more likely the bike is to stall.

I'm attaching a pic of the replaced spark plug and from all I know it
shows signs of a too rich condition (no oil though), but I'm not
100% if this is normal with this bike.

I'm thinking that maybe the revs are too low when idling or smth and
that's why it stalls but it doesn't if I don't do the sudden "brooom" so
I'm really not sure. Even if it was the case I don't have a tachometer
to attach to it so I'm not sure how would I adjust this. So far I
haven't made any adjustments to the idle speed. Also, I haven't
take the bike out since I first parked it for repairs so I don't know
whether not using it for 1-2 months can be the culprit some how.

Ideas? Solutions? I really need some help here

Thanks a lot!

Hey Serowbot, thanks a lot for the info. Just a question though. Any idea why this didn't happen before? Is it normal to have to adjust the idle speed after an oil change or once in a while? What about the sparkplug picture attached, does it look to you like its running too rich? From all I know that sparkplug was there for something like 10 months. If this is the case, is there an easy procedure to adjust this?

Yeah. I have the stock one but as the problem started after the oil
and filter change and got better after replacing the sparkplug I'm
trying to find some logic to it :/

A thing I mentioned in my first post that I'm not sure you considered
but I keep thinking it's related is that the chances of the engine stalling
increase if I open the throttle more.

Do you guys see some pattern on this? Something I could have done wrong in the oil/filter replacement process maybe? something else to
check before pumping up the idle revs?

That plug does look a little black and sooty. Probably running a little rich. Have you rejetted the carb? Maybe a previous owner did? "Old" thinking on this forum was a little on the rich side. Thanks to Dave and his O2 meter tuning we've started to rejet with a 50 pilot and 150 main (plus you may have to play with the washers to adjust the midrange).

Sounds like a carb problem to me.

Mann and original front

Kris01 Thanks for the info.

I do suspect there's a too rich condition too but this bike was idling ok before the oil+filter change so I'm inclined to think its not carb related. Although I would love to get some help with the carb adjustments/rejetting latter on

I'm not sure about the previous owner rejeting it tbh. Will try to find out. Anything to look for other than wear on the carb's nuts and bolts?

Has the brass plug on the idle mix screw been removed? If so, maybe it has been rejetted.

Let me try to find a picture.

Sitting 2 months is enough time for the ethanol fuel to corrode something in the carb. It is also enough time that the fuel can begin to degrade...fresher fuel may help considerably.

Most likely it is more apt to stall when you open the throttle more....because the RPM's are higher.  When the engine is spinning and you close the throttle after the "BROOM"....the jets that meter fuel are all closed except the idle (pilot) circuit.  The high vacuum pulls a lot of air past the slide and butterfly - but there is very little fuel to mix with it and the fuel mixture therefore goes horribly lean.  The TEV valve in the carb is supposed to help with this condition....and it may be plugged up.  I also believe the TEV was set up to work with ethanol free fuel - and it may not richen the mixture enough with E10 to correct for the lean condition.

Make sure your idle is high enough, add some Seafoam or other fuel system cleaner, and avoid going "BROOM" if that make the bike stall.  There really isn't any reason to go "BROOM"....the bike doesn't achieve any benefit from that - just gently open the throttle and ride the bike....cracking the throttle open on this bike really doesn't serve any purpose.  If after running a few tanks of fuel through the bike the situation doesn't return to normal or the bike is not running well...then take the carb apart and clean it.

If you have not been riding the bike and that black plug condition was discovered after starting the bike on choke and warming it up in the driveway.....don't worry about it.  You really need to take the bike out and ride it and get it fully warmed up before a plug reading has any meaning.