Reply To: Carby 250 dies when choke turned off
The float seat was a little restricted yes, so it’s a good job you have cleaned out the mesh cone that’s under it. Now the bike can correctly meter its fuel.
Feeding fuel straight to the carb is okay with a clean auxilary pump, just make sure there is an inline fuel filter as you will never know , micro debris may be present in the fuel than our eyes can see.
Was the airbox still connected and fully secure ? And also if you spray under the airbox rubbers and carb engine rubber pipes, with carb cleaner, do the revs change ?
It may explain the slow drop of revs as it’s either
– Hunting for fuel to idle down (clogged pilots / mixture screws too lean / airbox suspicious)
or
– intake manifolds on the engine have a micro leak somewhere
or
– Vacuum hoses have a leak (double check they are blocked hard if not using fuel pump and fuel tank)
You can clean the fuel pump yes , but open it. Don’t use air compressor, just a gentle washout with the carb cleaner helps.
No need to spray carb cleaner inside the “silver” hole of the pump , as that’s just for air vacuum.
If the fuel pump is faulty , it will be slow to deliver fuel or if bike is switched off , fuel will leak in to the silver vacuum hole , then leaks in to intake manifold pumps (which is not good for engine health as fuel washes down piston walls and oil is like water and smells very very strong of fuel, this is a sign to immediately flush engine and piston rings may need changing
Which means your compression should be around 150-175 psi hot healthy. It will run at 130 psi but it isn’t ideal, i believe that’s a limit , which means rebuild time soon.
I assume clearances are spot on ? (can affect compression values too)
Or if possible, expect to change head gaskets while replacing piston rings or pistons with rings , this would be an opportunity to really inspect cylinder walls and valves are sitting nicely in the valve head.