Usually when the engine fires out the exhaust it is either running too rich , the timing is retarded, or the valves are too tight.Check the color of the spark plugs to see if it is rich.For the timing to change enough for it to backfire it would be something electrical like the ignition module.And lastly if the valves are tight, they will get tighter when everything is hot and expanded.I hope this gives you a direction to start looking.
o2 prairie 650 supertrapp idsx,dynojet jet kit,Diamond G module & air box snorkle,HL clutch kit,Moose front and rear bumpers(rear mounted upside down, front mounting tabs welded onto frame lower than headlights), 2 inch lift with 28 inch itp 589's,front 2500 lb. winch and rear 2000 lb. winch,60 inch cycle country plow with electric lift and angle.
1964 Chevy Malibu conv. 355 cu.in. 4 sp. two stages of nitrous 850 hp at crank [email protected]
1970 Chevy Nova 396 auto tubbed and caged.
2000 Ford F350 4x4 7.3 diesel 538 hp 925 lb. torque at crank
1994 HD Dyna wideglide 96 in. S&S custom wheels and paint
1972HD FLH 1200 port and polished heads,sifton cam, aries piston,lightened flywheels,5 sp. in a 4 sp. case trans
1994 prostreet HD sportster 1200 105 hp. 180 rear tire ,midglide front end ,custom wheels,removeable wheelie bar.
Special construction 96 cu in rigid, 10 in over springer,250 rear tire,5 sp w/kick and electric start,3 in. open primary,foot clutch hand shift.
08 Skidoo 800 Renagade XP
02 Skidoo 800 Summit
He who dies with the most toys dies with an empty wallet(and usually single)