Well there is a clue to your issues.I changed the Plugs as well and think I may have damaged one of the end caps at the external end, could this be an issue
Best to take them off to do it properly. Otherwise like you say it just chucks it through the inlet valves, if it blows through that far! It would more than likely just shift it around inside the carbs and lodge somewhere else. To do it properly you need to remove the mixture screws, blow through there until it blasts out the hole the main chamber by the butterfly flap. Take the jets out, blast them through and all the orifices in carbs. You got the tiny holes in the emulsion tubes etc.n the mean time if i take the airbox off and fire some carb cleaner down the carbs and run the bike would that help clean out the jets or just go straight into the heads?
If you can get the carbs off that's the hard part done. Just undo the screws to the float chamber. Remove the float which is held in by a pin this slides out. Just push it out with tip of screwdriver. Needle valve sit beneath this and lifts out. And the jets are just like bolts with a hole drilled down the centre. Flat head screwdriver for the two jets in each carb and IIRC 8mm spanner to remove emulsion tube which holds the main jet in the end. Just don't overtighten them when putting back in as they are brass. Count the turns out on mixture screw, watch the little spring and rubber washer on them. Do one carb at a time and don't bother with the diaphragm that will give you a headache with the spring replacement until you have seen it done.
Blast all orifices that you can see with cleaner inside float chamber, main chamber where the slide and butterfly flap is and air holes on top of carb. Put jets, needle valve and float all back together. Then put mixture screws back in and count the turns back out. Job done, simples. Once you have done it once you will wonder what all the fuss was about.
Carb work always sounds more complex than what it actually is. What is difficult is messing around with jet sizes, needle height, mixture etc. The Black art as you call it.
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