Haha Eric I love how you had no idea the other day now you're telling people now :p

You mightn't have circlip grooves James, but you can use shims.

Also to add: although my car runs "rich" now into the 30's with MPG and that is not hanging about

Oh harris . Is there anything else apart from needles and main jets that needs altering ?

from what i know . Screws control air/fuel on idle and lower revs. Needle mid range fueling, and the main jet is for mid/higher rev mixture. What do i need to do to the main jet holder ( bolt ) and jet next to it ( think this is pilot jet ) ?

The main jet holder is the emulsion tube. You can tune the holes, and also get ones with a different taper inside them.

Main jet still dictates a lot of flow through the needle, they actually effect it virtually everywhere, regardless of what charts say, my AFR gauge and spark plug colours show different

Hmm, When you got your's on a Rolling road did they change the curclip posistion etc ? Or just main jets and tune screws :S ?

Can i just pay you to come give me a hand lmao ?

yeah rite, just had a peek. no clips, so going to have to use shims .. case of add a shim on each carb to richen the mixture ? or tother way round ?

Get main jets somewhere near first

145 I'm going to use for a base ..3 and half screws out .

Just get it on idle first ey ?

Payday needs to hurry the F up lol ..

When does the elmusion tube come into play ?

Virtually all the time haha. The main jet; needle & emulsion tube all work together.

Well my emulsion tubes do nothing actually haba

Fuck NA bike carbs, does anyone know anything about jetting them FI!

That would be me. Hahaha.

You can get needles specific for a turbo setup. Some bike guys go with a 5th injector approach. but it is possible to do it without that, You would need a selection of slide springs to find the best point that the slides open with the onset of boost or shim the needle up enough.

There is a picture here somewhere of a set of boosted bike carbs and how to do them. My setup is already planned out, I just need to get round and actually buy the parts and do it. Lol.

I was gonna, and still want to, but cant really on a daily. If i had another car my polo would be modified properly! haha.

Iv just wrote a bit of a guide about fuelling methods, hopefully be in the FAQ.

Its strange how easy it is to convert them to run boost, seeing how hard it is to convert a conventional downdraught carb,

Cymro, why do you think turbo-ing them will be easyer? I'd have thought it would have been more difficult!

The idea of having one throttle sounds interesting, but it seems the jetting is quite straight forward too, after reading about it,

It seems the idle jets and needles stay pretty much the same, or to begin with anyway. The pilot tube size and design dictates what size main jet the engine runs best with, there's a few calculations to do etc, but again it all seems straight forward enough.

Rite just done this quick mock up on paint ..

Could i Use this ?

What happens to the lift pump if its hard wired like so ? will this Cause it to over fuel and put to much pressure through lines ?

only reason i ask about hard wiring is that the pumps are controlled through ECU.. :/

Please tell me if theres any problems in the way i've layed it out .

Cheers

You've wired the relay wrong.

Put the inertia switch to ground instead of the pumps, then where you have the output going to ground put that to the pumps, then ground them

Do you mean the pins are wrong etc nick ? If so it was only to show what goes where etc :) ..

I always thought u put the inertia switch on the live :S

Cheers for heads up though :)

Yeah but who's to say what current rating the inertia switch is.

If you put it in the wire that turns the relay on and off it will still kill the pumps

Also, I ain't using a lift pump with a bike pump

Edited 20 August, 201214 yr by harris.racing

Ohh.. have you just removed the live feed to the pump or took the pump out itself ?

Aye, put it on the low current side of the relay.

You can't not run a lift pump can you?

Just reading nicks guide agaain and at one point he says

After market pump the same T piece method can be used, its worth adding:

A mk3 fuel sender with lift pump, fuel can be dragged through this, whether the lift pump is running or not - no need to modify

So i guess you can, Could i also modify the over flow/drain on the bike carbs to take the return line ? This would stop them both from beeing left to the atmosphere ?

Ah right, thats good to know. Never new that. Id still rather run it, its there for a reason.

Yeah but surly it would cause a pressure build up ?

Do NOT connect the breathers to the return.

Trust me I thought that was a good idea and the slight resistance was enough to make it run rich.

The return pipe is submerged in fuel in the tank so there is a restriction

What about using a catch tank, I was thinking of using a catch style bottle .. Then there would be no restriction if the bottle had a opening at the top ?rite ?

I've got my breathers attatched to some pipe each, which go over to the left of the bay , so basically if any fuel does spill it dont go on the manifold lol

I have a catch bottle.

Did you actually read the fuelling guide? Lmao

Its strange how easy it is to convert them to run boost, seeing how hard it is to convert a conventional downdraught carb,

Cymro, why do you think turbo-ing them will be easyer? I'd have thought it would have been more difficult!

The idea of having one throttle sounds interesting, but it seems the jetting is quite straight forward too, after reading about it,

It seems the idle jets and needles stay pretty much the same, or to begin with anyway. The pilot tube size and design dictates what size main jet the engine runs best with, there's a few calculations to do etc, but again it all seems straight forward enough.

I can never work out with superchargers how you limit the boost, turbo's waste gate opens at set boost and boost stops rising (ie the low pressure turbo Saab 9000 has a wastegate fixed at 6psi) regardless of what you do it will only generate 6psi (unmodified), superchargers confuse me.

Ye, single throttle plate means a proper plenum but I have seen an issue that when the throttle plate shuts the vacuum in the plenum might pull open the slides so to combat this you would need to use a pitot tube in front of the butterfly external of the plenum, (the standard design for turbo bike carbs is using the butterflies on the bike carbs then connecting the bowl vents to the plenum)

You can get Turbo needles for certain carbs, they have a step to literally dump fuel in at full boost or have a sharp taper, other systems use a 5th injector/fogger to enrich at boost (also helps cool the charge further).

CBR 900 needles kinda look like turbo needles but they're actually leaner