2G 420a popping noise from exhaust

[MasterMatt209]

My brothe just had the top end of his 420a rebuilt we went by the shop after hours to pick it up he started it and he said his rpms were jumping around. His exhaust sounded very weird too it would pop frequently sometimes pretty loud I'll have a link to video shortly. Anyone know what it could be? I figured the shop would have made sure everything was okay but apparently not. Maybe misfiring?

 

[MasterMatt209]

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Here's the video

 

[Priority DSM]

Does he have straight pipes no resonators/cat.

Sounds good to me. Like my '64 Harley.

 

[AK Maniak]

Sounds pretty decent to me

 

[MasterMatt209]

Straight pipe and no trust me it was popping pretty bad pretty sure it's a misfire

 

[Kela]

Straight pipe and no trust me it was popping pretty bad pretty sure it's a misfire

Maybe your mechanic didn't did good job on valves. This is what engine usualy does when it has bad valves. They don't close well

 

[project96gst]

2 step and antilag!