87 moto4

[Snow]

Hello. Just joined hoping to get good help. I got a 1987 moto 4 on trade. Went to start it for the first time and flame shot out the carb and caught the air box on fire. Timing looks to be good. The intake valve had no gap. Would that be the reason? Thanks

 

[Awk08]

Hello. Just joined hoping to get good help. I got a 1987 moto 4 on trade. Went to start it for the first time and flame shot out the carb and caught the air box on fire. Timing looks to be good. The intake valve had no gap. Would that be the reason? Thanks

an intake valve hanging open sure would cause a backfire

welcome to BF

 

[Larry's Shee]

Awk is right, set the valve lash/gap on both valves to start with.