bike carbs on a 1.1 (here we goooo)

nah mate its a 1.3 running the same bike carbs you got on your beastie, i think the problem is there constant vacuum carbs and there just isnt enough vacuum to get the needles to lift, maybe ive got the angle on the carbs wrong, just wondered if you had similar problems/a solution????

heres a gratuitous photo, im quite sure theyre the same


also instead of using the cable mount off the bike carbs, because the pierburg was so appauling i hacked the cable mount off the side then welded that on the top mounting rail for the carbs

ahh see, im not running them any more.. why not change the needles in them, they are adjustable.

if ya take the top off and pull them out theres a small clip that you can move on the needles. put them further in and they will idol with less fuel. im not sure about mix screws and stuff, also have you balanced them? thats the hard part

another thing i notice on that set up is theres no vac hose going to the distributor, if i were you mate i would run a t-piece from one of the vac hoses off the carb and stick it on the distributor or your timing wont advance when accelerating.

you've got me thinking now i think i might ger em out for another try on the weekend and see if i can re-jet them
i got a local bike shop i can go get the jets from, just need to get one out.


has yours ever started with the carbs on?

hi mixer do you know where i can get a cheap swirl pot filter from
bobby

if im honest i dont know what balancing is????
ive heard it mentioned but never understood, and the vacuum pipe probably explains why when i give the throttle some it just cuts out, but yeah after a full day tinkering finally got it running sunday night at around 10pm…needless to say the neighbours werent best pleased with the induction roar, i certainly was    restored my faith in the old tin
i think the needles might need to go up a notch, gonna take them apart this evenin and see if i can adjust, its running too lean i think its quite rough on startup and the starter motor is a brand spanker…but still getting fuel vapour coming out the wrong end

hi mate, unfortunately not as i used a regulator and a t-piece off the pipe before the regulator.

hard to explain

so i drew this



what i forgot to put… which i realize now is that i didn't put the fuel pump on there lol… the pump was basically before t-piece but after the tank… if ya know what i mean

this isnt the right way to do it, but for testing purposes i did this basically cos i didnt want to spend 100 quid on a pot that i was only going to be using for running the carbs, of which i dont run now any way.. lol..

ill be putting them back on this weekend so ill try and get them jetted right. if all goes well ill be buying a swirl pot and doing it properly

Right, quick idiots guide to bike carbs!

There are a couple of versions, the ones above are called cv (constant velocity,) carbs. Basically, at Idle, the fuel is supplied by the idle jet and the air bleed screw (mixture screw,) which will adjust the mixture ONLY at idle.

As the revs climb the needle takes over supplying more fuel as the needle rises.  On cv's the needle rises due to a pressure imbalance as air is sucked through a couple of drilling's and creates a vacuum above the needle and piston.

You come onto the main jet usually at about 7/8ths throttle and it's open fully at wide open.

Balancing is matching the airflow of all carbs.  You set one to a base line, usually open about 1.5-2mm, (I always do this with a drill bit used as a feeler gauge, if it just slides under the throttle plate at rest then it's set.  This is a bit more than on a bike, but cars generally have bigger idle drilling's and setting them a bit wider open can help with idling.  you then need a vacuum gauge to set them all up to match the vacuum reading of the 1st one.  I'd recommend doing this with whatever air filtration system you're using attached to the carbs, as all filters differ and they can make a a noticible differance to balance, sepecially if you use individual k&n style pod filters.

The swirl pot can help, I would say just get hole of one off a big block mk1/2 golf. some polo's had them too. heres a pic,
It's the black pot on the front of the engine. one of the fuel pipes goes over the engine to it, I believe thats the return, the inlet from the pump goes in at the bottom, and the outlet to the carb is next to the return line.

That should return the excess to the tank rather than past the float valves in the carb.  You will want a fuel pressure regulator as well, or a bike pump will do the job too.

Jon.

You don't need a pressure regulator or swirl pot at all. Your T piece is set up the wrong way. If you have:

 Fuel in    T     Fuel return

           Carbs

This will make the fuel run in a continuous loop. The carbs will draw the fuel they require when they need it. Works a treat for me, and many others. I'm also using the bike fuel pump because it was cheap, and i'm using a polo head with doesn't have space for mechanical pump. I'm not sure if the mechanical pump is capable of providing enough fuel? But then i'm running a tuned 1.3 gt, so may be different for 1.1  

sack all that confusion…
just gave £40 for an electric bike pump, got some plate steel for nothin for a blanking plate, half an hour gettin it setlled in it runs sweeeeeeeet

haha so it was pushing the fuel past the valve then..

are you jetted to suit too? if you are, what size jets u using?

i know mine will be smaller but i just wondered what size you had as i think mine were rejetted to 117.5's before i got them… still havnt put them back on tho, i got a little wasted last night and just done nothing all day maybe next week if i can be arsed lol, too much body work to finish..

i went down to a local bike shop and the friendly gent behind the counter basically told me convert engine size to mm and thats close enough to the jet size you need, so opened mine out slightly to 1.3mm runs wonderfully now, yeah mate the mechanical pump was too powerful for the carbs it was ramming fuel through and flooding the engine, ditched it for the pump with electrical cut-off, was the best £40 ive spent on the car so far…know anyone that wants a pollished pump?
was gonna record a video but the engines had a full rebuild and, well lets say its having teething problems, water pump blown, camshaft end seal melted! (NEVER seen that one before) so every free moment i get is spent tinkering, hopefully in time for volkswagen festival at harewood house  problem is i'll end up buying more bits there and it'll carry on……are these cars EVER finished?
 :dontknow: