My MC21 won't start unless I squirt a bit of fuel into the carburettors, then once that fuel is burnt the engine stops. I've checked there is fuel in the bowls and the throats look clean. I haven't gone further until I have more info as the on-line workshop manual isn't all that clear.
The bike stood for many years in the weather before I bought it, and it took some time to get all the electrics working. It has weak spark but obviously enough to fire the fuel.
I found compressions were low in both cylinders and put that down to the length of time the bike stood idle. A bit of oil down the plug holes brought compression up and I'm hoping once I can run the motor for a while the rings will seal.
My questions are: Is there an electric fuel cut off solenoid fitted to the carbs; How do I check to see if the reed valves are working and would they cause the no-run symptom; Does the PGM control the fuel into the cylinders.
Thanks in anticipation, Wellsy.

There is no electric or vacuum fuel tap. The PGM does not stop fuel getting to the carbs from the tank, or from the carbs into the cylinders.
The PGM does control the air correction solenoids, but this will not have a HUGE effect on things and certainly will not stop the bike from running.
Very basically, the PGM mainly makes slight changes to the fuel/air mixture at mid-range rpm. And of course is responsible for the ignition advance curve.
It sounds as though the jets are blocked or the float valves are not opening.

As a bare minimum, I would pull the carbs off, remove the float bowls, remove the slow jets, main jets and emulsion tubes and make sure that they are not dirty or blocked.
Also check that the float valves are in good condition and working properly, and check the float height.

While the carbs are off you can look down into the reeds with a torch, or push them open a bit with your fingers to get some idea of what's going on and remove them if necessary.
I doubt that the reeds are the primary reason for your engine not running, going off the fact that the engine runs with the aid of "manual" fuel injection.
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[color=#808080][size=9]Yes,.. I too know how to waste Time and Money,...

Have you checked the fuel tank outlet/tap isn't blocked or one of your hoses?

nxrsr20 wrote:Have you checked the fuel tank outlet/tap isn't blocked or one of your hoses?

Yes, ran separate hose from the tank which is sitting on a bench above the bike - most of the fairing is off so I removed the tank to access the coils etc - there is ample fuel to the carbs and I'm thinking the inner components will need cleaning as Tuckerbag suggests. Will take the carbs off and go through the process.

TuckerBag wrote:There is no electric or vacuum fuel tap. The PGM does not stop fuel getting to the carbs from the tank, or from the carbs into the cylinders.
The PGM does control the air correction solenoids, but this will not have a HUGE effect on things and certainly will not stop the bike from running.
Very basically, the PGM mainly makes slight changes to the fuel/air mixture at mid-range rpm. And of course is responsible for the ignition advance curve.
It sounds as though the jets are blocked or the float valves are not opening.

As a bare minimum, I would pull the carbs off, remove the float bowls, remove the slow jets, main jets and emulsion tubes and make sure that they are not dirty or blocked.
Also check that the float valves are in good condition and working properly, and check the float height.

While the carbs are off you can look down into the reeds with a torch, or push them open a bit with your fingers to get some idea of what's going on and remove them if necessary.
I doubt that the reeds are the primary reason for your engine not running, going off the fact that the engine runs with the aid of "manual" fuel injection.

Many thanks, I'll take them off, as the bike has been idle & in the weather for years your suggestion will mean less problems when I eventually get on the road.