On my ryder I started hearing a loud BOOM / Backfire when I turn off the ignition key. I have recently replaced the inlet needle along with the bowl gasket & fuel filter and spark plug. Everything seems to be in tip top shape except now it is backfiring thru the exhaust when I turn off the key. I have already plugged in the two wires into the fuel solenoid but I cannot understand why I am now getting this BOOM ing noise when I turn off the key. Any input please ? Thanks.