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Cool yea man I checked all that and they are all blowing through nice and good.
Took the bike to work this morning as the weather wernt too bad and its back to running like absolute crap again, couldn't even get it to run over 4k :/ so could be the repaired diaphragm come loose again, i ordered a new one from NRP, 40quid for a little bit of rubber, those guys are making some bucks on that stuff! Spose beggars can't be choosers though.

Hopefully, an after-market in-line fuel filter is being used.

If an in-line filter isn't installed before any gasoline enters a freshly cleaned carb, the carb may become instantly re-clogged and require another dis-assembly and re-cleaning.

The petcock screens alone, even when in perfect condition, provide inadequate fuel filtration.

Good Fortune!

SK - those little needle jets should just about fall out mate.Give them a push if you have the bowls off or maybe you can gently pull them from inside.

I had a look at the timing advancer today, the internals were spotless so didn't touch them. I find it hard to believe this bike is 32 years old sometimes its beautifully clean in places and seems like the 18,000 miles shown on the speedo is must be truthful. I think that perhaps the PO must of treated it with more love than his wife lol. Well, apart from the grubby carbs.

I checked the battery, coils and some of the electrics also as per diagrams from Patton and I think these readings are on the good side?:

Battery: 12.21 ignition off /11.70 ignition on

Coils from red cable to frame/battery negative: 11.18
I checked some other random points like cables coming out of relays etc and they were showing around 11.35 volts
Does this seem roughly correct?
I'm still learning in this area so im a bit shoddy on the dark arts of electrons ohms etc.

With a good fully charged battery and properly functioning charging system, measured voltage between battery posts at 5000 rpm should be 14~15 volts .

To help determine condition of the battery, could have it load-tested at your friendly local auto-supply store, Walmart, etc.
Would remove and service the battery and charge it overnight just before having it load-tested.

Good Fortune!

Ok cheers mate I'll take the battery off and give it a good service and see what its holding afterwards at 5k revs.

Just spotted this set of carbs on eBay for sale in the UK. They are only asking 56quid plus free p&p for same year model but a shaft drive so got to be worth a shot for that price! The carbs look pretty dirty but should be able to clean them up, salvage a bunch of bits n swap stuff out etc etc im just hoping that some experimenting will get the bike running good again:
pages.ebay.com/link/?nav=item.view&id=221660622208&alt=web

Just spotted this set of carbs on eBay for sale in the UK. They are only asking 56quid plus free p&p for same year model but a shaft drive so got to be worth a shot for that price! The carbs look pretty dirty but should be able to clean them up, salvage a bunch of bits n swap stuff out etc etc im just hoping that some experimenting will get the bike running good again:
pages.ebay.com/link/?nav=item.view&id=221660622208&alt=web

Could be worth a shot. might get you those needles and diaphragms you were interested in.
I see they are sold. Did you buy ?
Good luck

Yea thought I'd go for it, at the very least theres a bunch of cheap spares, after paying forty quid for that diaphragm rubber the other day they should pay for themselves a few times over if I need any spare bits.

A good addition to your spares SK - hopefully all is good inside. What was the total for them mate ?
Guess you already know the fecking crazy NEW cost of those little parts.

£56 including postage so not too shabby, I'm hoping they are fairly decent inside too. They look pretty manky from the pics and it looks like one of the fuel screw housings have been repaired so I'm betting the bowls are going to be hideous, but as long as its all there I don't mind too much. I'm getting a lot of experience with cleaning carbs out atm so just another challenge to be met!
I'm gonna have a tinker around with it all anyway can't hurt to try another set just in case it is still carb related.
I was reading through my Haynes manual last night and I came across a section at the back that has "1983 onwards models" which Ive somehow completely missed up until now, and it has the H4 model specs listings in it, doh! Seems the carbs on it are the correct ones, they just happen to have all the same settings and sizes as the earlier N1 hence my confusion, still strange how the jet sizes on the later models are so much smaller than the years before but least solved that one.
Think I need to be a bit more observant!

Been tinkering again today, Checked electrics again, battery running at 14.5 volts at 5k rpm, coils are good, getting blue or white spark off plugs, so i think electrical and ignition system is all good on this bike.

The idiots at Royal Mail managed to lose my new diaphragm i ordered from NRP carbs after taking it back to the post office and subsequently filing it in some god knows where place, so frustratingly havent been able to change that out yet, Lucky i have those other carbs coming next week though so i hopefully get a good one off them even though my second fix appears to be holding for the mo.

I took the bike out again today for a quick ride, it still feels like a big lean issue, the bike bogs a bit when revving from idle, and the revs hang or go back to idle really slowly from 3k downwards. i can get the bike to rev a little higher in neutral now, still only up to 6k or so but hard to get it over 4-5k when riding.
Im wondering, if im getting hanging/slow back to idle revs is that more likely to suggest an external air leak rather than an 'in carb' type of lean fuel condition?
Thinking again about changing the manifold to carb rubbers for new ones just in case.

Also im a bit confused on this bit as im reading different things on fuel levels, can anyone tell me where i measure the float bowl fuel level from? is it the top of the bowl as in the line where the bowl separates from the top of the carb (where the gasket is) or lower down from where the top of the indented bowl edge bit is?

Cheers

Hanging idle could be a small air leak, sticky throttle cable, carbs badly out of synch

Measure the service fuel level at the seam between the carb bowl and the carb upper body. Use a ruler or mark the tube. I found that eyeballing the level was not good enough. If the level is out of spec then turn the carbs upside down, measure the float height and bend the tang so that the float height is adjusted the required number of mm.

The pic below is taken from the Kawasaki shop manual - the one from mbsween's site. The carb section is worth a read
Good luck