Engine braking will be reduced if something is holding the revs high.
On an 11xx, the symptoms noted would be consistent with throttle cable seating or inlet air leaks.
Look at where the throttle cables meet the throttle bodies and make sure the cables ends are properly seated.
Check that the little rubber bungs that seal the vacuum take-off's on the throttle bodies are in place (the ones that you connect gauges to when balancing the throttles).
Check the connections of the throttle bodies to the inlet stubs on the cylinders and the air intakes to the throttle bodies.
Caveat: I've never messed with a 1200 (but the checks above can't hurt)
Edit: or as you're in that there London, book it in to Steptoe.
On an 11xx, the symptoms noted would be consistent with throttle cable seating or inlet air leaks.
Look at where the throttle cables meet the throttle bodies and make sure the cables ends are properly seated.
Check that the little rubber bungs that seal the vacuum take-off's on the throttle bodies are in place (the ones that you connect gauges to when balancing the throttles).
Check the connections of the throttle bodies to the inlet stubs on the cylinders and the air intakes to the throttle bodies.
Caveat: I've never messed with a 1200 (but the checks above can't hurt)
Edit: or as you're in that there London, book it in to Steptoe.



