[twisty]

imported post

dave t. wrote:

hey how is everyone doing i need some help and advice on my 86 gl1200i it is back fireing some usually happens after i have rode 15 to 20 miles then shut it off for a while usually 20minuate or so then when i start it up it will back fire i use 93 octaine fuel and keep the plugs and filters changed and set at least every 2500 miles any help will be really appreciated thanks dave t

Dave your Wing has a (lost spark) type ignition.. What that means is it sparks each cylinder at both TDC compression & TDC exhaust. If there is an ignitable (burnable) mixture in a cylinder at hot cranking it will fire that off & it will pop back through the open exhaust valve &backfire in the exhaust. Some seem to do it more than others, if the engine is stopped with an open intake & exhaust valve on the same cylinder the hot muffler & convection flow will pull fuel & air into that cylinder & leave a stoichiometric mixture in that cylinder. A slightly internally leaking carb can also allow fuel into a cylinder that will ignite on hot re-cranking, a small hole or leak in the exhaust can also allow a backfire at start-up..

The best cure is to add a single fire ignition but that isn't available for the 4 cylinder Wing.. Another cure is to add a 2 revolution cranking delay to the spark system so it cranks over twice before sparking any cylinder (not practical to do).. You might try turning the R/H handlebar kill switch to off before cranking, then once it starts cranking turn the switch on.. If that stops the backfiring then you will either have to live with the backfiring or start it like that, or play with the throttle & choke to find a place it will start without the backfiring..

Twisty