hello again

im sure everyone is getting fed up with me posting about my carbs, but i do not believe im educated enough in this department, i can do my single cylinder 2 stroke motorbikes though LOL

i have a 1.8L zetec blacktop engine with ZZR1100 bike carbs on, the carbs have 45 pilot jets in 170 main jets, the air screw is 2.5 turns out.
i have a facet 1.5-6psi fuel pump with a fuel filter just before the pump and a adjustable pressure regulator just before the carbs, i also have a one way valve fitted just after the regulator, the regulator is set to 2.5psi.
i have a wideband 02 sensor fitted with the correct display.
my Ecu is just one of the ford ones that controls ignition.

i upped the pilot jets from 38 to 45 as i was running way to lean with a air ful mixture of around 20 on the gauge, now its about 13 but i feel that is okay and rich is okay at tickover. when im stationary i give it about 1/4 throttle throttle it leans out. now id now think about moving the needle up a notch but the needles arent adjustable on these carbs as its done through vacuum. so now i am lost.

ive always believed the 1st quarter throttle is done through the pilot jet and the air screw, 1/4 to 3/4 throttle is done by changing the needle height, and the last 1/4 is done by the main jet.

i dont know if anyone can help me with this matter, ive been trying for a while to get these carbs set up and im getting fed up. im going to try and ring bog bros during the week.

we are having a dyno installed at work which i can use when its in but we are still building the new unit to house it in.

i cant take it for a blast as im in the process of re building my front brake calipers.

can anyone give me a hand or lend me some knowledge.

i do not know how i can sort this problem. if i had a dyno id just do a power run see whats going on exactly with the fuel/air ratio at certain rpms underload and then go from there, im sure someone must have roughly the same setup as me though...

THANKS

I would suggest changing the fuel pump and all the bits and bobs you have there for a matching bike pump instead.

They pump when the float is opening the needle valve and stop when it closes. This is all very precise at low pressures and if you have constant pumping, even at 2.5psi this can overcome the float needle valve and cause a lot of problems.

There's plenty cheap ones on eBay and even some brand new ones for £30.

[Edited on 28/3/15 by coozer]

+1
Use bike pump with correct bore pipework
Its low pressure high volume you need , and a bike pump cuts out when its reached pressure
Whether it cures it or not,youll know its correct
I had to go bigger mains to get mine pulling clean
Its worth the faffing when theyre done though

So if I got the pump off the bike, and just wired a 12v feed to it and earthed it out, It would still cut in and out as it saw fit doesn't need any alternative sensors or anything?

Thanks

Yes, its a clever little intermittent pump.

I would also suggest going to Bogg Brothers to get it setup correctly. Dave did my 1.8 with zx9 carbs which are essentially the same and they were spot on. Good 40mpg on a long run going to shows etc.

All that needed doing is the correct needle height, and drilled the mains out, correct air screw position to get to spot on. No need to change the original pilot jet on mine.

[Edited on 28/3/15 by coozer]

Is there any load on your engine or are you just revving it up? you may be worrying too much at this stage, I would stick with the pump you have at the moment until proved wrong.

The taper on the needle controls the mixture as the piston rises, on some installations you need to blank the air bleed vent - middle hole on the air filter side of the carb its about 3mm dia.

However, I could never get my 1.8 to run well on the 40mm ZZR1100 carbs, I switched to ZXR750 carbs, which are 38mm, and are the ones you rob the tops off for full power ZZR1100s. With the 170 mains in the 750 carbs, it ran perfect, the new owners have done 40,000 miles on the setup. I think it was more the needle profile which was better suited than the smaller venturi.