kel eg
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| posted on 4/4/15 at 05:22 PM |
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Honda Bike Carb conversion - Help needed
Hi guys il give you an intro into my Civic. Heres how i bought it:
After plenty of welding and painting:
Anyway the rad and everything is on now all fluids are in there but im having a problem with the bike carbs.
I currently cant get the engine to turn over but that could just be a weak battery.
The main problem is that the bike carbs are leaking fuel underneath. Im not familiar with carbs so this has been a big learning curve.
Im using a bike fuel pump from a CBR600 and the carbs are CBR600 F2 carbs. The leak is coming from the spouts underneath the carbs.
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whitestu
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| posted on 4/4/15 at 05:32 PM |
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The most likely cause is the float valves are dirty and not seating properly. Take them apart and give them a good clean.
If the carbs are at a different angle to how they were on the bike you may need to alter the float height as well.
Stu
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kel eg
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| posted on 4/4/15 at 05:41 PM |
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I did have them all cleaned before they where fitted but that was a while back.
I believe on the bike they are nearly virtical, I couldn't get them to anywhere near that angle.
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David Jenkins
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| posted on 4/4/15 at 05:56 PM |
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I run my CBR600 carbs about 10 degrees above horizontal - don't worry if you can't manage to get them vertical! 
I second the idea that the float valves might be dirty. Also, check that the choke mechanism is fully off (it's usually spring loaded to off) -
this basically drips fuel into the intakes when set to on and, as such, is quite a crude mechanism. It doesn't work the same way as a normal
car choke that limits the air going in - it adds fuel instead.
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kel eg
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| posted on 4/4/15 at 05:57 PM |
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Ok cheers i will look into the choke, I may just strip them down and fully clean them again.
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maccmike
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| posted on 4/4/15 at 10:13 PM |
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Could the 'spouts' be the float drains?
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kel eg
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| posted on 6/4/15 at 07:48 PM |
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It is the drains the plugs where loose. My error!
Anyways now they leak from other places so im thinking maybe these carbs are not to be used with a bike fuel pump.
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40inches
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| posted on 6/4/15 at 07:56 PM |
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quote:
Originally posted by kel eg
Anyways now they leak from other places so im thinking maybe these carbs are not to be used with a bike fuel pump.
Bike carbs should be used with a bike pump. The clues in the name 
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kel eg
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| posted on 6/4/15 at 07:58 PM |
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I am using a bike fuel pump. Im wondering if the bike initially had no pump at all.
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David Jenkins
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| posted on 6/4/15 at 08:01 PM |
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^^^^ what he said!
Bike pumps give a large volume at low pressure, which is perfect. It's what I use for my CBR600 carbs, and it was a vast improvement over the
general-purpose car pump I had previously.
Just a random thought - you haven't got a pump meant for use with an injected bike engine, have you?
Have these carbs been sitting around for a long time before you fitted them? There are a load of little o-rings between each carb body, used as seals
in the fuel supply. For example, each pair of carbs is fed by a T-piece with an o-ring at each end - see below, on the left - if they have perished
then you'd certainly get a leak.
[Edited on 6/4/15 by David Jenkins]
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kel eg
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| posted on 6/4/15 at 08:03 PM |
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I was told the pump is off a 1995 CBR600 which is a carbed bike so it should be the correct pump. I may fit a regulator just to see what pressure its
supplying.
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David Jenkins
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| posted on 6/4/15 at 08:07 PM |
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Should be fine - you won't need a regulator with that.
NB: see my edit to the last post.
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kel eg
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| posted on 6/4/15 at 08:08 PM |
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I will try to figure out exactly where they are leaking, but yes they could have been sat around for a while before i bought them.
I will try to identify the leak and then strip them back down check the condition of the O rings.
Thanks for your help so far guys.
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David Jenkins
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| posted on 6/4/15 at 09:00 PM |
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It should be fairly easy to test those o-rings: turn on the ignition so the pump is running, then waggle/rotate each of those fuel inlet t-pieces as
far as they go. If they're in good condition then they won't leak, but if they're perished then maybe you'll see fuel
leaking.
If they are leaking, look at my website to see how to split the carbs (look in the menu for bike carbs). It's
an easy job, but a bit time-consuming (and you need to pay attention to detail).
[Edited on 6/4/15 by David Jenkins]
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mark chandler
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| posted on 6/4/15 at 09:30 PM |
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You are feeding fuel into the correct pipes?
On my cbr900 carbs there were overflow pipes, pretty obvious fuel delivery pipes and a third set that went to an air breather into the air filter that
looked like a fuel pipe.
Just a thought.
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whitestu
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| posted on 7/4/15 at 10:11 AM |
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I've never seen the fuel connector 'O' rings leak even on old bikes.
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David Jenkins
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| posted on 7/4/15 at 10:29 AM |
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Worth a look though, if someone is struggling to find leaks - and it's a simple check.
I still reckon it's dirt in the float valves. 
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19sac65
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| posted on 7/4/15 at 01:20 PM |
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Try making up a small bottle of fuel and a pipe to the carbs
See if they leak with gravity pressure only
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compturbo
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| posted on 8/4/15 at 12:23 AM |
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I ran my bike carbs using a bike fuel pump on a T-piece setup. The pump runs constantly, pumping fuel in a loop from the tank to the engine bay and
back to the tank. There is a T-piece in this loop to the carbs. This way they just draw the fuel they require. Not sure if that would help here?
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whitestu
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| posted on 8/4/15 at 07:58 AM |
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quote:
I ran my bike carbs using a bike fuel pump on a T-piece setup. The pump runs constantly, pumping fuel in a loop from the tank to the engine bay and
back to the tank. There is a T-piece in this loop to the carbs. This way they just draw the fuel they require. Not sure if that would help here?
They aren't supposed to work like that as they don't need a return. Having the pump constantly running will most likely shorten its life
quite a bit. Bike pumps have a mechanism that switches them off as soon as they are up to pressure.
Your setup could cause mixture problems as well.
Stu
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