suzuki DT9.9 backfire

[iceman52]

I have a 1989 or 90 DT9.9 with low hours, it has a backfire through the exhaust when running, it runs good but the backfire slows the engine enough to prevent idling. it will backfire every 2 seconds at slow speeds, engine revs up and it's not so noticeable. it has clean fuel and carb has been cleaned, any ideas where to look

[Hoosmatroos]

Could be an air leak somewhere. Gaskets from carb to inlet oke? Adjustment from the carb to lean?

[gordonm1]

that sounds like a fuel problem to me. the low speed backfire has been connected with fuel starvation.

since your motor still runs, a heavy saturation with fuel additives with fresh fuel might clear the problem up. I just got my carbed 15 hp running with a long soak and vibration. my low speed jet was plugged.

I read and searched and an enzyme additive was said to be the best for ethanol fuels. I can't say what brand but the bottle looks blue and they had it at oreillys and Walmart. I have been through two bottles and had to soak my carb for 5 days and actually hooked up a vibrator to my carb soaker to undo ten years of no use.

get some carb cleaner in there right now or start wrenching on the carbs.

[Hoosmatroos]

This was 2 months ago. I think he solved the problem but forgot to report back