"pop" or "misfire" on quick throttle?

[taoster]

hey guys, this is the first time riding this bike for more than 2 miles after i bought it. Its a V-TWIN with V&H Co2 intake, bassani road rage full exhaust, and Ivans flash (tuned for Intake and slip-on, not full exhaust) and new spark plugs. There was maybe 2 gallons of old fuel(i'm not sure how old, could be from mid 2019, or could be from january 2020) from the previous owner and i topped it off with name brand 87.

So while slowing down to a stop, i would do a quick rev to rev-match for a smooth downshift, and sometimes it would "pop" and hesitate to rev up. It would just be for that split second that it wouldn't rev up. This happened numerous times when giving it a quick throttle burst. But not all the time. I'm leaning towards old gas but i'd just like some confirmation. Any help would be appreciated! Thanks guys and be safe!

 

[motomania2007]

What bike?

Popping on downshift or closing the throttle is caused by an exploding unburned fuel inside the exhaust and happens on downshift or throttle closing as that allows oxygen from the air into the exhaust where the oxygen meets hit exhaust gases including unburned fuel.
Air can come in from the outlet of the he muffler or through any joint in the exhaust.

 

[taoster]

What bike?

Popping on downshift or closing the throttle is caused by an exploding unburned fuel inside the exhaust and happens on downshift or throttle closing as that allows oxygen from the air into the exhaust where the oxygen meets hit exhaust gases including unburned fuel.
Air can come in from the outlet of the he muffler or through any joint in the exhaust.

It’s a 2014 Yamaha bolt. It’s not exactly like the popping from decel. It’s as if it’s sputtering. More like one single sputter if that makes sense... and this happens as I’m giving it a quick rev with the clutch pulled in.

 

[squidworth]

I think to a certain extent, what you're experiencing is inherent to v-twins. If you can post a video, that would most definitely understand whats going on. I've had an 08 Superduke and 08 Tuono that have similar behaviors during downshifting.

 

[FLH03RIDER]

As motomania2007 said... "Air can come in from the outlet of the muffler or through any joint in the exhaust." Check for leaks a long the exhaust and also the intake.

Don't those motor make a bunch of gurgling and popping noises in stock configuration anyway? Stock exhaust reduces most of those kinda noises.
I'm going with the current "tune" and the exhaust system on the bike exacerbating the issue.

Oh wait, isn't that engine a 60deg with a staggered firing sequence? Ha, ha... that explains the weird noises! :laughing JK

 

[bobl]

I think the OP is talking about a pop and a hesitation when accelerating the motor to match speeds when down shifting, not on trailing throttle, but on opening throttle. That sounds more like a lean condition on opening the throttle. If it were mine, I would call Ivan and check it with him. He seems to know his business. Another thought would be an air intake leak at the carb/head/manifold junction. That could be checked by spraying WD40 or something those areas. However, the new gas would be easy and cheap, and might be the problem.

 

[afm199]

Sounds lean. Dump all the gas and put in NEW gas and try it again.