after all the twists and turns of getting my 999 working properly again over the winter, it is now working really well. Except that under really force acceleration, I am getting a loud bang and a hesitation. Any ideas anybody??
Where is the bang from? Is it an exhaust thing (like when you shut the throttle with unburnt fuels igniting) of fro, the back (like the chain above) or the front (like headraces loose or front suspension topping out)?
Yes it would help if we knew what kind of a bang. Exhaust? Mechanical? From the engine? Transmission?
two up and under heavy acceleration, my fugly sounds like the big ends have well and truly gone. (by my self, long story) i'v traced it back to the exhaust/Cat mounting under the engine and the wife giving up the fags
Sorry, yes, a loud exhaust, unburnt-fuel type bang. It's difficult to tell if the hesitation is before, after or at the same time. It's often when I'm doing an overtake, so some poor car drivers must be getting terrified. It's only with large throttle openings and highish revs. Most of the time it's completely unnecessary to accelerate that hard, so it only happens once or twice per ride.
TPS reset was done six weeks or so ago. It did help smoothness and power but didn’t stop this problem. During the efforts to get it going, it did suffer some pretty hefty back-fires and I can’t help wondering if my Pipercross filters got damaged in the same way as the cafe racer 999 filters did a few weeks ago.
Take it to a knowledgeable dyno operator and see if you can replicate the bang. I assume something to do with ignition time/map.
It has a new cps and the (standard 999) map was recently flashed to the ecu - the same map that was previously installed. It runs perfectly otherwise. The bike has a power commander but the settings haven’t been touched. No dynos in this immediate area.
Maybe - worth a try but it was fine before the work to get it running and then not. One thing I changed is the pump assembly. I got the wrong new filter and ended up putting the s/h filter in in my impatience. Even though the assembly looked pristine, I don’t know how many miles it’s done. If it’s clogged, would it do this??
Big bangs suggest mistiming of ignition to me. Spark plug is a good suggestion, IMO. I'm no expert but I do remember my old Suzuki deafening me with backfiring due to a mistimed sparking issue. Very loud.
higher the pressure in the cylinder, the higher the pressure (V) required to push the sparks. any weakness in the HT insulation, it will find another route to earth. never say never, but, hmm, i dont think its HT related.
Spark plug integrity may be sufficient to accommodate adequate sparking at idle and at moderate revs but possibly break down at peak revs. Sometimes it's a game of millimetres and milliseconds. Faulty HT lead insulation would tend to manifest in failed sparking, with loss of power ... but probably no "banging". Another issue that used to manifest in my old and beloved Suzuki, especially in the wet.
