Dave Grant

[Dave Grant]

Hi l have a 115 V4 Yamaha Outboard that hasn't yet done 10 hours. When giving it a run after a few minutes it started backfiring. What is the problem?

[99yam40]

always give the model # so everyone knows what motor you are having problems with.

Sounds like a lean sneeze

[DougBradlow]

Yamaha V4 Backfire

Yep if its backfiring out of the carbs it is running to lean and could eventually burn a piston or blow out a reed valve.You need to back out the idle adjustment on both carbs until the coughing backfiring stops.