Help - Running like turd

[deepsky]

Soo almost finished fixing up my 92 xj600s which i bought as spares or repair - think it'd been sitting up for a while so I stuck fresh fuel in, cleaned carbs, checked valves (which are a little bit out but nothing overly major) and plugs... Turned out it was just the carbs needed a good clean to get it running.
Anyways, i dunno if it's pinking but when running there's an intermittent knock... Well, more of a 'clonk' and you can proper feel it through the bike and it kinda feels the engine sorta has to catch up when it does it.
Does it on idle or when revving, it's no more or less prominent or worse when revving compared to idle.

Also, over the last week its kinda developed a bit of an issue. It runs like crap when you've got the choke on and warming it up and wont idle off choke easily. tried adjusting idle but it makes no difference.
Also has a really flat spot about 1/5th of the way on the throttle and you gotta proper wind it back before itll pick up.
Airbox is all connected as are breather hoses - it was running fine before.

Unfortunately it's just running on the stand atm as I havent got an mot on it yet and can't ride it so dunno what it actually rides like.
In any case, it really doesn't sound terribly happy at the moment.
When it was running a week or so ago when i originally got it all cleaned out and running pukka it idled and ran beautiful, no lag or hesitation at all on throttle so I doubt there's anything terribly wrong with it.

Ideas?

[bobh]

It's not pinking - that would only happen under load. It could just be that it is misfiring every now and then, and the knock is the transmission going from drive to driven.

I'm thinking maybe water in the bottom of the tank? Or a duff HT lead?

[deepsky]

Can you test HT leads on a multimeter to see if they work? I assume you'd check for resistance?

Could be water in fuel actually, didn't think of that will check - its been standing outside with only a few litres in.

[CD]

Water in fuel is common - the filler cap leaks.

Also make sure all carb choke plungers are moving free and the seal inside are good and soft.

[deepsky]

Well, I've poked, prodded and hammered virtually everything and today suddenly it's burst into life and is running perfectly so I've not a clue what it actually was that cured it...

Happy days!

[neilmud Lord Protector]

Thats the trouble wiv bikes they are like wimmen show them a firm hand & they are better ;D

Running & ducking the flack Neil

[deepsky]

I just gave it the strongly worded ultimatum that if it didn't sort it's act out that it wouldn't be getting a good hard ride.

So yeah, just like a woman :-D

[CD]

Sounds like the worn wire of doom. Go over the wiring loom - all of it - with a torch, magnifying glass and fine tooth comb. Look for rubbed wires and green contacts inside the connectors blocks.