Jump to content
Notice to Hotmail/Gmail & BT Internet users - Please check your SPAM/JUNK folders for our emails. Please add our email as a contact to your email account.
Light/Dark Mode Enabled: You can now select the option by clicking the moon/lightbulb in the top right corner!

Mk2 1.3 gt 3f bike carb conversion help needed


Recommended Posts

So I know there’s a lot of bike carb forums about but I cannot for the life of me find one with the problems I’m having, so I’m all set and ready I’ve got a set of cbr600 carbs they may need balancing and tuning for the engine but fuelling the carbs is setting me back, I’ve gone for the bike pump route and I’ve wired it up to the relay above the fuse box in the mk2 pump runs when the key is turned but it doesn’t turn off? It just keeps pumping and eventually fuel starts coming out the brass holes which I assume are breathers below the trumpets, so if anyone can point me in the right direction that would be great, thank! 

Link to post
Share on other sites
  • Replies 5
  • Created
  • Last Reply

Top Posters In This Topic

  • Mrskarz

    3

  • Eviljohn

    2

  • caretakerplus

    1

Top Posters In This Topic

Popular Posts

What I know about bike carbs you would get on the back of a postage stamp and still have room for a letter - BUT I do have many years of experience on other types of carburettor, so, as you have gone

I briefly had bike carbs on my old polo. My understanding is that bike fuel pumps are low pressure and also pressure sensitive so the fact yours doesn't stop fuelling is worrying.  When i first f

caretakerplus

What I know about bike carbs you would get on the back of a postage stamp and still have room for a letter - BUT I do have many years of experience on other types of carburettor, so, as you have gone all week without a reply, I offer the following which may be of help to you.

 

It sounds to me as if the relay that you are using is 'latching' (contacts remaining closed then the coil is de-energised) This may be the design of the relay (a latching relay) or it may simply be that the contacts are 'sticking'.

The pressure of petrol from the pump to the carburettor(s) needs to be LOW enough NOT to push past the needle valve when the carburettor float rises to the maximum fuel height, otherwise it will leak as you describe.

Now I do not know if your carbs actually have needle valves as such, or if they may have a diaphragm arrangement, but the principle is the same, so I would suggest that, once that you have sorted out the relay problem, you look at ways of regulating the fuel pressure, this could be achieved by using a fuel pressure regulator valve, which would return excess fuel to the tank.

You should also consider ways of switching 'off' the pump (preferably automatically) in case of accident, where the car could, for example, end up inverted - the last thing that you want in that situation, is to keep pumping petrol onto a hot engine!

 

I hope that you obtain more information specific to your particular carburettors.

 

Regards.

 

  • Thanks 1
Link to post
Share on other sites
  • 1 month later...
Eviljohn

I briefly had bike carbs on my old polo. My understanding is that bike fuel pumps are low pressure and also pressure sensitive so the fact yours doesn't stop fuelling is worrying. 

When i first fitted mine, i had it in the engine bay, on the inside of the wing, over the wheel arch. Didn't work great, kept cutting out. Did some reading on locostbuilders, (lots of xp on bike carb conversions on there,) and they recommended mounting it as low as possible as they are also gravity fed. They don't "pull" fuel too well but they can push it. I moved mine and mounted it in the bottom of the bay, (i was told fitting it behind the tank at the rear of the car would be better but wasn't able to do it at the time,) but just moving it to underneath the engine made a huge difference. 

As a safety cut-off, i had an inertia switch and fuse that i wired in. Inertia switch was easy to pick up off ebay. Doesn't have to be from a specific car so long as it works. No idea what mine was off. Ran a wire from spare coil terminal to power it. They're easy to test and reset too. So if you get one, put it somewhere accessible. 

Hope that helps. Good luck.

  • Thanks 1
Link to post
Share on other sites

Right so here’s where I am now, so the pump I had was a EBay cheap cbr600 pump that was over fuelling I got rid of that I tried a facet posi flow mounted under the boot floor and that actually overheated within a couple miles so now I’ve gone and bought another cbr600 pump from an actual shop and that’s actually doing me well atm! It primed and stops and pumps when it’s suppose to but I’ve noticed it pumps realllyyyyyy slowly when I go over a bump here and there  so I might have an air leak somewhere which I’ll check soon, but thankyou for the reply’s! Much appreciated 

Link to post
Share on other sites
Eviljohn

I had facet posi flo and pressure regulator to start with along with cbr 400 carbs, (only running a 1l so didn't need 600's,) may have been because of mounting position, could have been the fact it was complete first time diy job or could have been the cursed carbs i had. That set up never ran right. Constantly overfuelled. Even with pressure regulator set as low as possible. Ran soooo much better with bike pump. You say the pump reacts when you go over bumps, how full is your fuel tank and also how did you mount the pump? I used some rubber coated P clips along with anti vibration mounts. 

There is a considerable amount of xp in the faq's on this forum for bike carbs. I can also recommend locostbuilders. The first kit i got was diy all the way. I got a full bolt on kit from danstengineering who are very knowledgable. Also, depending on where you live, it may be worth finding a motorcycle garage and finding out what you can from them about the parts you have.

Again dude, good luck. Hope somethin there helped.

Link to post
Share on other sites
  • 2 weeks later...

So cars still going strong (sometimes it has a hiccup) yeah so basically the bike pump I have is under the boot floor same place as the facet in the short pull long push config and it works but it doesn’t stop pumping completely when the cars running at traffic lights for example it will click here and there so I must be using a fair bit of fuel for it to keep pressure 😅 and sometimes it will stop pumping and the car dies but if I leave the ignition on and give the pump a hit with the palm of my hand it jumps back into life 😂 so it’s working but it’s not 100% 

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
  • Recently Browsing   0 members

    No registered users viewing this page.

Announcements

  • Notice to Hotmail/Gmail & BT Internet users - Please check your SPAM/JUNK folders for our emails. Please add our email as a contact to your email account.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue. Terms of Use Privacy Policy Guidelines