My 94 sport 400L has been backfiring lately. Mostly on start up but occasionally it does it when i turn it off.
It seems to backfire where the elbow pipe meets with the main pipe of the exhaust. (stock) It is also very hard to start. Just cranks and cranks then BOOM, it backfires...like setting off some TNT. (does this sometimes but most of the time it isnt that loud). Once i get it started it seems to run/idle fine until i shut it off again. Then the same problem occurs. Just changed the spark plug too(black, oily, wet). Any suggestions: air leak, fuel mixture, blow by, throttle, choke, rings, water....

Thanks

Jeff

 

If your plug is wet and oily then your mixture needs to be checked out. That might just be your problem?!?

 

Yea, I was just gonna say we had this problem about 3 weeks ago on my dads Prairie 400. Getting it started for the first time this year and it just wouldn't start. I changed out the plug and poop, started right up. It did need to be ridden a little to get it going good. Thats what I told my dad, take it out for a little WOT once in awhile, he's always babying the thing. Seemed to be the only problem.