Jolfa's FAQ / How to guide to bike carbs

Discussion in 'Throttle bodies & non-OEM ECUs' started by Jolfa, Dec 16, 2008.

  1. Jolfa

    Jolfa Forum Junkie

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    First and foremost, if you need any of the parts mentioned in this thread, PM me, I can supply everything you need ;)

    Secondly please, please stop PMing me, e-mailing me and generally harassing me with questions about this. EVERYTHING is covered in this thread if you actually take the time to read it properly!!!

    Since I had to ask every question possible really about doing this, I thought I'd make a guide for future clueless fools :lol: so maybe one for the FAQs?

    This guide is for a 16v but it'd be the same principle for any engine, though you would need a custom manifold not just a chopped up standard one.

    I used 45mm Keihin carbs off a Kawasaki ZX9R to put on my 6a, but almost any carbs would be largely the same.

    You will need

    • Carbs
    • Manifold (standard one can be used)
    • Length of silicone hose that won't collapse under vacuum
    • Fuel pump
    • Fuel pressure regulator (unless using the pump off the bike)
    • Some jubilee clips
    • Screwdrivers, allen keys and pliers/grips

    So we start with this -
    [​IMG]
    [​IMG]

    What you don't need

    You'll be getting rid of almost everything to do with the old injection system - Inlet mani, airbox, injector lines (all of that will come off together no need to take it to pieces) anything connected to the above, any plugs here can be left unplugged - all redundant. Then main fuel pump and one of the fuel lines going to it/from it. Don't need to touch the lift pump in the tank, that can stay.
    [​IMG]

    The manifold

    To use a standard manifold, its simply a case of chopping down the lower section until there's just the flange and a small bit of inlet left on each (enough to clip some hose to).
    Then you'll need to block the injector holes - I used 1p pieces for this, but it meant that the oil breather vacuum underneath was redundant. Using sump plugs to block them should still leave this vacuum useable to plug your brake servo into :thumbup:

    [​IMG]
    [​IMG]

    Otherwise you'll need to get a manifold made up from somewhere like Bogg Brothers or your local fab place (or find someone who's had one modified already who wants to sell it for cheap like me, cheers Ash! [|)] ).

    The carbs

    I would advise at least checking over your carbs before just slinging them on, turns out mine had 2x 160 and 2x 165 main jets [:s] which although odd, did seem to do the job ok to start with, but I swapped them for 180 mains from Allens Performance for about 3 each. Some have said they're a little big for the job, so you may want to look at 170/175's especially if you're carbing a KR. You can drill the existing jets out, but for the price of new ones it didn't seem worth it.

    Swapping the jets is pretty straight forward, just undo the 4 screws under the carbs to gain access - you should see something like:
    [​IMG]
    That underneath. The main jet I have circled in red. To remove it, hold the base with an 8mm spanner and undo the jet with a flat screwdriver, simple! I didn't touch the rest of the jets so the plate can now be put back on

    Next set the mixture (green circle). Screw that screw all the way in and 3 turns back out, I was told 2 1/2 or 3 1/2 from different sources so I went for 3 which seems to do the job.

    Yellow circle is pilot jet, blue is starter jet. You don't need to worry about these.

    Once back together, check everything moves freely and is clean, connect them up to your manifold and make double sure the jubilee clips are sitting properly on the carb flanges and are tight!!! And they're good to go.

    Putting it all on

    I'll start from the fuel pump - I used a Facet silver top which I put in place of the old pump, using one of the old pump studs to mount it (it earths through this too) and then plugged the live into the existing pump plug so it still primes the same and cuts off if you stall :thumbup:

    Then I used the line from the lift pump (easy to find out which one this is by turning the ignition on with it disconnected - it'll be the one p*ssing out fuel :lol: ) to feed the pump, and what was the return line (blue) from the pump into the engine bay. The old feed was then redundant so it was removed.

    [​IMG]

    You'll then need to mount your regulator in the bay (unless you're using a bike pump in which case ignore this step), I used the 2 studs on the drivers side suspension turret, which meant the fuel line could reach too.

    Next, with your carbs already mounted to your manifold put the assembly onto your engine. It's a ballache getting to all the bolts but it's easier than putting them together on the car...

    Run another fuel line from the regulator to the fuel on the carbs, which is underneath - the 2 big lines going to a T-piece. I had enough spare hose from ripping out the redundant hoses to do this :)

    All you've got to connect then, is -
    The throttle cable, I used the existing cable with the nipple on the end trimmed slightly so it fit in the holder. And (an idea stolen from gunit-84 on here) used the old cable holder off the old manifold modified slightly to hold the cable in the right place.

    And the brake servo - which is plugged into the old oil breather between #1 + 2 inlets which I've joined to the servo end by a piece of sturdy old coolant hose.

    I binned the chopped manifold in the end and went with one with extended ports I picked up cheap, the spacing however was still too far out so I chopped it right down again and joined it back up with silicone thus solving the problem!

    Et voila!

    [​IMG]
    [video]staj7RKroSc[/video]

    The fuel pressure needs to be set at 3psi which you can change on the regulator, obviously you'll need a gauge. If you use a bike pump the pressure will always be right so no need for a reg!

    Then it's just a case of fiddling until you're happy :thumbup:
    [​IMG]
    Red= Choke, I used a 2m bike brake cable to connect this for now
    Blue= Throttle position adjustments which sorted my engine idling at 5000revs
    Green= Idle speed control, just wind it up or down easy peasy
    All the extra hoses you can see in the pic I'm lead to believe are for coolant, except the ones at the top, which are breathers. I removed them all :)

    Problem I've encountered so far

    The hoses between the carb and mani keep sucking themselves off the carb end... This was due to mismatched spacing on the carbs and mani, so I rectified it with an extra silicone join lower down :)

    At first it wouldn't start without turning the fuel pressure up so high fuel was p*ssing out of the breathers, then it wouldn't start on it's own steam at all and had to be towed until it fired. This I will put down to vacuum leaks all over the shop - mainly caused by the above problem.

    When I did get it to start properly it idled at 5200 :o as per the fiddling part, this was sorted with the throttle posistion adjustments.

    Throttle is rather sticky, which I think is due to the hoses touching the throttle linkages. I'm hoping to cure this with an extra spring...

    I can't get my dipstick into the guide anymore, there's no space :lol:

    Cost of conversion

    Carbs - 36 eBay
    Mani + hoses - 20 gunit-84 (original one was free off a mate, but left me with no brakes!)
    Pump + reg - 60 davey
    Jets + a T-piece - 16 Allens

    = 132 [:*:]

    Sold all my K-jet bits for 235

    = 103 profit :lol:!

    I'll make any revisions to this as I find out myself (and try and get some better pics)!

    Just don't fill yourself with hope it will start, idle, run and drive right first time! [><]:lol:

    HTH :thumbup:
     
    Last edited: Mar 8, 2014
  2. Rallye_Will Forum Member

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    Nice write up.

    Are you not using any filtration on the air intake?
     
  3. Jolfa

    Jolfa Forum Junkie

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    Hopefully it'll help someone else out!

    No filters yet, no money it all goes on petrol it's thirsty as f*ck! [><]
     
  4. velly_16v_cab

    velly_16v_cab Forum Junkie

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    great write up....i bet it sounds the mutts nutts!
     
  5. EZ_Pete

    EZ_Pete Forum Junkie

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    Nice write up.
    Not sure about your Allen key collection resting between the battery terminals in the first pic though. [><] :lol:
     
  6. lufbramatt Forum Member

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    haha- one of my mates still has a scar on his hand froma 3mm allen key shorting on ther terminals of a radio control car battery pack when we were 15! would hate to see what a car battery would do! hehe

    nicework on the carbs tho [:D]
     
  7. Jolfa

    Jolfa Forum Junkie

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    Ah it's alright :lol:

    Original post edited, at 'et voila' ;)
     
  8. benlg81 Forum Member

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    hi mate

    just wondered what the difference has been since you fitted these?

    more response more power? looking at doing this on mine at the mo just wondered if it was worth the work?
     
  9. Jolfa

    Jolfa Forum Junkie

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    More response, far more power (though my K-Jet was knackered and half of it wasn't plugged in), sounds better, pulls better :thumbup:

    It just absolutely drinks petrol, and causes me no end of grief having to fix it every day :thumbd:
     
    Last edited: Dec 19, 2008
  10. ihaveajetta Forum Member

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    I want to put a 16v in a carbed car and run it on bike carbs, what do about the fuel pump and reg. Etc?
     
  11. Gareth83 Forum Junkie

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    excellent guide,

    where did you get the hose from?
     
  12. Jolfa

    Jolfa Forum Junkie

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    Pass, just get the bike pump has to be the easiest/cheapest option :thumbup:

    Pass again [:p] both lots came with the manifold both times :lol: ...The first lot was utter sh*te though!
     
  13. rocco2litre

    rocco2litre Forum Junkie

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    bet it runs as lumpy as hell?
    what mpg 15?
     
  14. gunit-84 Forum Member

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    mine doesnt seem to bad? 2.0 16v with bike carbs, not usde as a daily tho, would probly change my mind if i were filling it up twice a week! i reckon mine does 28/30 average.
     
  15. Jolfa

    Jolfa Forum Junkie

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    15? :lol:

    30?! :o

    Try 3...:p

    ..Still plenty of tinkering to be done yet :lol:
     
    Last edited: Dec 20, 2008
  16. EZ_Pete

    EZ_Pete Forum Junkie

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    I wouldn't run it much in its present state Jolfa.
    To be running that inefficiently, you must be getting a hell of a lot of unburnt fuel in the chambers. This'll coke up the head, and wash the oil off the bores, like nobody's business. (Unless the petrol's actually leaking out somewhere before it gets into the engine [:s] )

    You'll probably find it'll go even better with the fuelling better sorted. [:D]
     
  17. Jolfa

    Jolfa Forum Junkie

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    That would explain the masses of blue smoke I had the other day that seems to have sorted itself and left me with the same oil level I had before...

    Anyway, I've leaned the mixture out half a turn and turned the fuel pressure down a smidgen.

    Need to get hold of my mate to borrow his rolling road for an hour or 2 really! I already figured it'd be better when it's actually set up properly :lol:
     
  18. sam-ski Forum Member

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    how easy would it be to bike carb my 1.6 driver :p
     
  19. Jolfa

    Jolfa Forum Junkie

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    Same thing I guess, but you'd need a custom manifold :thumbup:
     
  20. sam-ski Forum Member

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    hmmmm

    what sort of power increase do you expect to get from it?
     
    Last edited: Dec 26, 2008

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