Hi all can anyone suggest how I stop my WD B40 popping.I have ajusted mixture and Timing no better.
Its a push fit into the head and is quite a good fit
Thanks
Paul
Is it like mine, popping when engine braking?
Check for an air leak at the inlet manifold/carb.
Been busy riding other bikes. Got a couple of minutes to check. The exhaust pipe seemed to be a tight fit in the head. But connecting an air hose to the end of the silencer revealed a subsantial leak. Also a small leak in the joint between pipe and silencer. Will see when I have time to fix it.
Would that cuase a popping exhaust? I'd say it would just create blowing from the leaks.
My money is still on an intake air leak. Excuse me if I'm wrong.
Exhaust gas exits the head through the pipes, if the force of the exhaust pressure is greater than the pressure acting in a forward direction all is ok. Let the throttle off and pressure reduces, a leak that lets air in at a higher pressure or speed can enter the cylinder through the exhaust valves causing the back fire.
Putting an airline on the silencer does nor necessarily confirm a leak in the exhaust system, dependent on the position of the valves the air could escape through the bellmouth.
On second thoughts...perhaps not!
I had engine at compression stroke and could feel air leaks with my right hand. A good thing with high level exhausts.
Put a mark on the pipe where it came out of the head. Dismantled. The pipe could now go another 5mm into the head. Practiced my blacksmith skills making a new bracket. Painted it black. Why does paint take so much time to dry? Cut off rear end of the pipe an inch. Makes it possible to fit silencer without removing rear shock. As I sometimes is a belt and braces type, smeared on high temperature silicone on joints and assembled. Had an hour tour on the Ninja to cool a bit. Today +30C. Then a test ride. No popping. Problem solved.
Even better, the lack of response at more than half throttle gone, now pulls much better.
Top job and obviously down to air leaks as others suggested. Soemthing else I've learnt.
Hi all thanks for all the responses,
Yes it pops when the throttle is fully closed on over run, if I open it slightly it pops less
Mike can you tell me what silicone you used as I would like to try that on my Exhaust
The carb and manifold are all good fit , new o rings and seals. The carb is fitted to one of amals screw on filters .
Thank you
Paul