03 RX1 shooting flame out of carb

[Josh.h]

So I just got an 03 rx1 that is back firing a flame through the carb and in the exhaust. So a little about this sled. So I bought it for 500 buck because the kid I bought it took the head of and didn't time it and cranked it and bent all the valves. So I bought and had a mechanic put a new head on and time it right. He got it to start but was hard to start it. So I had him clean and rebuild the carbs and he gave it back to me. So I took it to the yamaha dealer and he had it for 3 months and come back to me says it's a fuel pump so bought a new one and I picked it up and brought it home. Started try to ride it around act like no power but though it would be bad fuel drove for about 6 minutes and when I pulled infront of my shop it died. Won't start I can crank and crank but won't start. I see fuel pumping and like I said it's back firing. Any thoughts? I did see that the chain case tensions was not even on it the 2 bolts were gone so I pushed back in and put 2 new bolts in it.

 

[NLP_SLED_GUY]

Do compression checks. My initial thought is the valve timing still isn’t right.

This is two months old. Did you figure it out?