09-11-2017, 04:59 PM
(09-11-2017, 01:22 PM)Hugh Barnes Wrote: Yep, as described, pump behaves flawlessly... OM carbs are far less sophisticted that later series models and don't have such things as breather pipes (I think). To be clear, when I open the throttle, the engine will die completely - almost as if one had run out of petrol or someone had turned the ignition off in error...
Today task is to track down a replacement manifold to eliminate that...
Hi Hugh,
It stills feels like ignition to me?
However if you think it's mixture related (odd with black plugs) - it does sound like how an unchoked cold engine responds with flatness / coughing / spitting? That may also fit in with the cooler weather at this time of year compared to June. How does it run on choke with the choke levers pulling the jets out? Or alternatively you could wind the mixture nuts down 3 or 4 flats and see if it runs like that and then back to normal when warmed up?
SU pumps can run OK on an open end but stall against pressure, something subtle to do with the spring behind the diaphragm. But you'll be able to tell if the pump is clicking or see the kick on the ammeter when it does.
Dave