Hi,
I recently offered to have a go at getting a 1969 Briggs and Stratton powered rotavator to run which a friend had inherited from someone on the allotment.
The engine is a B&S 3.5HP with a air flap governor, manual choke and pulsa-jet carby.
The engine had no oil to start with so added some SAE30. The compression has not been tested with a gauge- it is slightly harder to turn backwards than forwards (it has Easy Pull) so not sure if that is bad. The carby looks as if it has been replaced by someone trying to fix the motor as it looks very clean but had no diaphragm in the pump (which is on the side not the base). I fitted a new diaphragm, checked the jets- which looked v.clean, and fitted a new base gasket between the carb and the tank. I did not get a new gasket between the carb and the head which maybe was a mistake.
Anyway the problem is I can only get it to start by injecting some petrol into the throttle opening. Then it starts immediately and runs okay but a bit smoky. Without doing this injection trick the motor just won't start no matter how many times I pull the cord.
I have checked the spark and looks a bit weak. Setting the armature gap has made no difference to the starting.
I should mention that when I close up the air mixture screw the engine will cut out at about 1turn out position (keeping it at 1.5 t out seems alright).
Any ideas. Possibly poor compression, or leaking carb to head gasket, or points or condenser? Also my petrol mover has a B&S motor and that has a bulb you squeeze to inject a jet of fuel to get it to start. How is it that this sort of carb doesn't have something like this?
Any pointers of what to look at next would be much appreciated.
Thanks
Fossil Light
