NC23 Carbs cleaned and won't start

[The Porter]

Hi Wozza, Yes they did. I have changed the manifold rubbers as one was a bit worn on the inside, also the vaccum chamber seems to be missing the part that is inside of it that obviously creates the vaccum. Only just found out by looking at the haynes manual. She fires when easy start or petrol is poured down the carbs, fuel pump is working but the carbs are just not drawing the petrol through. I'm going to order a new vaccum float off the bay of e, whack it in with the new inlet rubbers and bob as they say should be your uncle? If not it can only be lack of compression so engine out...

[Wozza]

I doubt it would be float heights anyway tbh. Are all the jets standard sizes? Have you reset the pilot screws?

[The Porter]

Don't know Wozza, all I know is I gave them to a mechanic who cleaned them replaced a bloked jet or something and put them all back together. It looks like I have fuel getting to the carbs now but it still wont fire. I have a huge fat blue spark from all plugs, petrol pump etc all working fine, new battery. I have even tried jump starting from my car and still nothing. What little hair I have left i'm starting to tear out. I'm going on the mayday run tomorrow (have a gsxr750) and a few are mechanics so will bend their ears. I would try bump starting it but have taken the brakes off to clean, strip etc.

[Wozza]

I think you're gonna have to get inside the carbs and see what's what for yourself - check all the jets are clear, check jet sizes, check/adjust float heights, check needle heights, check slide diaphragms, check/reset pilot screws... I know you've had a mechanic strip and clean them but as it's still not working you really need to see what's going on with your own eyes.

[jac_is_smiling]

Not to make it seem like your treading water or going over yourself, but if you checked the spark before starting off the car may need to check the spark again, the carmay have overwhelmed the bikes electrics.

(Obv not needed if it still fires when petrol is poured down it)

As for checking the compression you can get a compression tester out of halfords for £10-20, altho you will need a small adaptor for the small spark plug hole, however doesnt sound like compression if it will fire when you pour petrol down it.

Sounds like its a fueling problem. Could try opening the drain screw a tiny bit on each float bowl to check that fuel is defo getting that far.
If youve got a haynes manual then checking the carbs is ok and straight foward.

[The Porter]

Cheers Lads, Petrol is getting through the carbs as have checked the drain screws and petrol does come out.
I will get the spark plugs out again during the week and have another check.
I have a mate who is very mechanically minded and he is over for a BBQ on saturday so said he will strip down the carbs and check everthing is set correctly. If he can't get it started it must be buggered.