Z1OwnersClub GB

Almost sorted the engine out and stripped the carbs which had 105 main with some sort of tapered needle,restrictor jets on the intake linked to the main.Bought a refurb kit replaced the needle and got some 100 main jets and left the restrictor jets out.Started up ok and took it out for a test ride and found I couldn’t get above 3000 revs,when I applied the choke it was great,so my assumption be it right or wrong that the main jet needed increasing in size.Used the 102.5 and then the 105 but now only getting to 3500.So a couple of questions for you guys,am I on the right track with the jets and I just haven’t got big enough and how much the restrictor changes the fuel/air on the main jet.The bike has k and n filters and a 4 into 1 exhaust

Sounds like the holes in the emulsion tubes are blocked and your only running on the pilot circuit.
Stock for vm 24 on a 650 is 15 pilot, 102.5 mains. If they are genuine K & N's then jetting needs to be 15 pilots, 105 mains with air restrictions. If they are random aftermarket filters then bin them and buy decent ones. Some aftermarket filters are more restrictive than the original airbox and/or block passages.
Never use anything other than original mikuni or Keyster brass parts. Just clean them and bin any aftermarket ebay shite.

try lifting the needles

I have replaced original parts that the bike was running 105 main and the restrictor but still no improvement.The last thing was the needles which seemed to be 5CN15 instead of the Y63 that came with the kit.On replacing the original needles they were not in good shape,one wasn’t straight and one had a repair with solder I think.So now I am looking for replacement for 5CN15 which I understand is discontinued

Think the khi number is Kawasaki 16009-1009.
Google and plenty come up on ebay NOS with cross reference part number 5CN15

Thanks for your help warren,found 4 original needles which should solve the problem,when it’s up and running might reduce the main jet size(it used to run a bit rich)

If you have the carbs stripped would be worth getting the choke plungers renewed with new seals , Zed1015 on here does a Viton ethanol resistant exchange service. Got them done on my RD250 which made a huge difference, just awaiting delivery of the ones on my 900A4 from him.

This is his EBay shop ,

https://www.ebay.co.uk/itm/255534054891 ... media=COPY