On fuelling:

Could I use a T piece and also a bike fuel pump?

e.g

Lift Pump > T >Return + Bike Pump

Bike pump > Carb inlet

Bike Pump return > Y Piece + Lift pump return

Shady drawing of fuel route

Are there any flaws in this plan? I already have all parts shown kicking about

Whats the point? Bike carbs only supply fuel untill the carbs are full and then they shut off.

Whats the point? Bike carbs only supply fuel untill the carbs are full and then they shut off.

So would you just cut the bike pump out all together?

It's just that people recommend using the bike pump with pressure regulators which I dont have so I thought the t piece would ensure pressure wasnt too high

BIKE pump. Is used for BIKE carbs... They were disigned for the job so why would u need a regulator ? :S lol

BIKE pump. Is used for BIKE carbs... They were disigned for the job so why would u need a regulator ? :S lol

Because of the lift pumps pressure being too high i thought, Am I over complicating things?

I'm planning on fitting a set of ZXR400 carbs to the breadvan for one last send off at GTI fest,

Engine spec will be;

3F bottom end + head

Newman 268/268 cam

4 branch manifold + Full 1.75" stainless system with single silencer

It looks like the carbs have come with 4x96 main jets, with 32mm chokes

Anyone got a recommendation on jet size to start off with?

I'm using 135 but i reckon its slightly lean. Id go 138 or 140 to start with, although mine are 600's

Aye, i've got less air-flow so require less fuel.

Nick?

Yeah but at the same time yours will have a higher state of tune, wont the cam ect require extra fuek?

Aye good point,

marks just pointed out that people running ZXR carbs usually require bigger jets than equivalent sized CBR carbs,

Which must be down to needle profile?

Yeah i hear if those guys running 170-180 jets sometimes!

Remember theres different types though so there not all measured the same way

Read the fuelling you bike carbs thread where I clearly state I have a bike pump and no lift pump!

Also max no idea on jets due to not being familiar with them carbs

Please can somebody post a picture/diagram of their coil wiring, i.e. Where the live feeds go to and which colour wires plug into which spade connector. Theres a lot of mention of the tacho feed but I'm more interested in the live feeds.

Thanks

iv forgot iv said it that many times recently

ignition feed to coil posi

green to coil negi, black to coil posi,

black lead on ignition loom to body/batt ground

i think anyway

Yeah i hear if those guys running 170-180 jets sometimes!

Remember theres different types though so there not all measured the same way

1.3 on ZZR = 180's

iv forgot iv said it that many times recently

ignition feed to coil posi

green to coil negi, black to coil posi,

black lead on ignition loom to body/batt ground

i think anyway

Thanks thats exactly what i needed, but this still leaves me with a spare connector on the coil, is this normal? I have two on what i assume is the negative side and three on the positive.

Got the big white plug with the green wire and the tacho red/white feed on the negi side and just a single black wire to the posi, so all I need there is an ign 12v feed?

Cheers for your patience guys

my coil has 3 connections on each terminal, doesnt mean they need to be used.

youll have two on the posi side and one on the negi, unless youre using the coil negi as your tacho feed then youll have two on either.

my coil has 3 connections on each terminal, doesnt mean they need to be used.

youll have two on the posi side and one on the negi, unless youre using the coil negi as your tacho feed then youll have two on either.

That's great thanks.

Right guys, blind fault finding time! :)

I've got everything set up. Got a strong spark. Plenty of fuel going to the carbs. But no fuel in the combustion chambers? Am I supposed to do something with the carbs to let the fuel through? Have set the throttle open slightly and cranked it plenty too.

Any help appreciated :)

Jets blocked ? there's a screw at the bottem off the float bows .. Undo it and see if it drains fuel out .. Least you can rule out fuel getting to the carbs.

After that could only be one thing and thats jets i guess

Spark at the right time? Choke?

Right guys, blind fault finding time! :)

I've got everything set up. Got a strong spark. Plenty of fuel going to the carbs. But no fuel in the combustion chambers? Am I supposed to do something with the carbs to let the fuel through? Have set the throttle open slightly and cranked it plenty too.

Any help appreciated :)

How do you know theres no fuel getting to the cylinders?

Its not like the SPI or single carb units where you can see a fuel spray.

Opening the Choke is a good place to start, but needs to be done with throttle closed, otherwise it will rev its tits off.

The throttle needs to be fully closed or you won't have the inlet vacuum needed to pull the fuel out the carbs - bike carbs differ from other fuel systems in that they only dose the fuel that the engine literally sucks out through a straw (that's why they're efficient), the starter motor alone can't pull much air through the carbs so for any of that necessary vac at all the throttle must be totally shut.

If your starter is a bit lazy, you can hold the throttles open with your right foot, turn the engine over, and let go of the accelerator (snapping the throttles shut) whilst it's turning over. Sudden surge of inlet vac can then better pull the fuel through.

i have purchased some yamaha fzs 600 carbs and am looking to fit some air filters. i am confused as to what side i need to put them on and iff i am missing any parts, I'm assuming they go on the side with the bronze coloured intakes like on a normal spi throttle, but iff some one can point me in the right direction , that would be appreciated. i am going to be getting four individual cone filters with jubilee clips.

Its the same as pm's...