Carb queries

[Phil C]

No I haven't done that. To my inexperienced eye the carb looks generally pretty clean, so I'm kind of thinking there's unlikely to be a blockage. But then I don't really know what to judge the cleanliness by. Maybe an ultrasonic cleaner is something I should consider - after all it can't do any harm (except a few more quid spent on something that would be used maybe only once.) I'll certainly keep it in mind, thanks Stubaker58 (unusual name you have there, makes mine sound pretty boring!)
You having a Monobloc makes me wonder what kind of carb would have been on my bike originally. From what I've read, the Monobloc was a good carb and the Concentric, whilst also pretty good, was built down to a price (I could be wrong.)
I'm keenly awaiting the result of chaz's investigation today - should help me narrow things down.
Phil

[Pete A10]

There is a YouTube video on unblocking pilot passageways on concentric carb may be useful - I can't work out how to copy the link!!

[Phil C]

Yes, thanks Pete, I saw one by Paul Henshaw, where he describes a common place for a blockage is the right angle bend furthest from the pilot air screw. But, as I see it, if I had a blockage there then when I squirt down the fuel passageway I wouldn't get any carb-cleaner spurting out of either of the two tiny holes, but I do get it from one of them. Anyway, interesting video. If I remember rightly he uses nozzle cleaners and thin wire. Actually, I've just this morning received some nozzle cleaners in the post, but won't be prodding around with them unless I have to, in case I do more harm than good.  Phil

[chaz]

Phil
pm sent, I would be wary on nozzle/jet cleaners as small ones can break off inside then totally blocked so take your time,  a cuppa and the door shut for no interruptions.. I also use small drills but take my time and  I have a good selection of small size ones.

[Phil C]

Thanks Charlie. Did you try squirting carb-cleaner into the pilot fuel passageway to see if it came out of one of the tiny holes or both?  Phil

[chaz]

Phil
the pair and single 300/301 showing blanked off holes. Its possible as these carbs are diy tuned items , someone removed a plug in the past but would only come out of one hole

[Phil C]

So chaz, just to be sure I'm understanding you correctly, please could you tell me these two things: firstly, are you saying you squirted carb-cleaner into the hole shown on the photo but it only spurted out of one of the tiny pilot holes in the bore, not both? And if that's the case, then was the hole it  spurted out of the one nearest the centre of the carb, rather than the one nearest to engine?  Thanks very much chaz.  Phil

[Phil C]

Sorry Chaz, got my holes muddled. If, with the bowl off and put to one side,  you squirt into the carb pilot fuel intake hole (threaded hole on the face which mates with the bowl top face) and watch the two very tiny holes in the carb bore, does it come out of one, or both? If only one, which one? Phil

PS am I testing your patience? I'm very grateful for your help!

[chaz]

Phil, here to help, if only I could get my motor right!!
squirting cleaner into either the pilot screw hole or the outside of the three (the opposite plugged) on the air filter side results in spray coming out of both small holes in the bore

[Phil C]

Haha 😁, thanks Chaz, yes but (I think!) you're still not squirting into the pilot FUEL hole (bottom left hole on photo attached.) If you squirt in there, does it come spurting from BOTH the very tiny holes next to each other in the carburettor bore? Phil

[chaz]

Sorry Chaz, got my holes muddled. If, with the bowl off and put to one side,  you squirt into the carb pilot fuel intake hole (threaded hole on the face which mates with the bowl top face) and watch the two very tiny holes in the carb bore, does it come out of one, or both? If only one, which one? Phil

PS am I testing your patience? I'm very grateful for your help!

thats where you threw me, the first time ive ever noticed the hole is threaded, I thought only the two bowl fitting holes are threaded,
just checked, only comes out of the slide hole not the engine side one.

note for future... next house... garage attached to house..

[Phil C]

So mine is the same as yours, which I assume is in working order. So I'm now going to refit mine to the bike (well, not tonight, but maybe tomorrow) and I'll see what happens. I expect you'll be hearing from me soon! Thanks again for your help. I'll try not to cause confusion in future!   Phil