Ok, here's the thing.
I've been working away since Xmas and now I'm home. The Buell has been lanquishing in the garage all this time, feeling unloved and probably sulking, as I've been looking at Grisos.
I took it for an MOT last Monday, after giving it a fettle and a clean, but it took a bit to get going and would not tick over. At low RPM, it was dropping on to one cylinder, but pulled ok when accelerating.
Anyway, MOT in hand, I rode it home the long way, hoping that the problem would disappear, but it didn't. Reading about stale fuel etc. I then treated it to a full tank of fresh fuel, new fuel line and new plugs. I removed the carb and checked the diaphram, float bowl etc. and gave it a clean using carb cleaner. I put a bit of Redex in the tank as well for good measure.
I fired it up and the problem remained. No tickover and "missing" on a neutral throttle, although it revs ok.
While keeping it running one one, I pulled a plug lead at random (rear) and the engine still ran. Great, I thought, it must be the rear lead, so I found one of a set that I bought at Sproutfest a decade ago, and swapped the lead. No difference. I held the throttle so that it wouldn't die and tried again, removing the front lead and sure enough, it continued to run on the rear cylinder.
Today, I had a bit more time, so I took it for a thrash to Dorchester, hoping I could determine what was happening.
It seems quite happy accelerating under load at any RPM, even low down, but at constant neutral throttle, it doesn't like it below 3500rpm. On the over run , with throttle closed, it feels like I've switched the ignition off, until I blip the throttle.
Acceleration response seems sluggish to me also. But it runs great at 80mph+ although it didn't appear to make 6800rpm (race ECM).

It's OK to ride, but I don't want to get stuck in a town centre............

Any suggestions most welcome.

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I started out with nothing and still got most of it left.

Clean the carb again, this time pay particular attention to idle and progression jets and drillings.
I see this a LOT these days, especially at this time of year

Better yet, look upon this as a good excuse to fit an HSR42

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

Grisos are sound machines

......just not as good as a well sorted S1

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Mithered ta death.
92 MB
96 S2T
98 S1W
00 M2
01 X1
03 P3
10 CR

I'll have it off again tomorrow.

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I started out with nothing and still got most of it left.

Mine is doing exactly the same, one minute it was great the next it was behaving exactly like yours, not had a chance to take carb off yet but hoping its just a bit of crap in the jet!
Keep us informed how you get on

Will do. I'm pretty sure that I'll take it to Belgium this weekend. Just a bit embarrassing in slow traffic.

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I started out with nothing and still got most of it left.

Just avoid Jill Brown then

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xxxx

How about concentrating on getting your bike fixed first......

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Valencia Orange XB12Scg - serviced by Maz 2018
Black P3 Blast - serviced by Maz and fixed by Maz in 2019

I would have thought the opposite applied.....at least the heat would be taken off of Mojo's problems....they would all be laughing at me...!!

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Valencia Orange XB12Scg - serviced by Maz 2018
Black P3 Blast - serviced by Maz and fixed by Maz in 2019

...........I set 'em up..............

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I started out with nothing and still got most of it left.

Problem sorted today! As Pash and Maz predicted, it was a blocked idle jet! We are back in business again, bike is now with my brother for the next two weeks so he can have a hoon whilst I'm sunning it up in Spain!!