I have a set of CBR600 carbs on my 1660cc x-flow. From early spring to late autumn I can set the choke (actually 'starting enrichment' - SE) and the engine will start first try.

When the car's stone-cold in the middle of winter (i.e. now) the car will fire but not quite run properly - it's turning over but will stall as soon as I try to blip the throttle... I don't think I have quite enough SE/choke. It takes me 4 or 5 attempts to get the engine running, after which the engine runs sweetly and the choke lever can be pushed home within 100 yards.

The SE pistons are being pulled out enough (and evenly across the carbs) by the cable.
All the passageways in the carbs are clean.
The floats have been set properly.
The battery lives on a maintenance chaarger when the car's not in use, so it spins the starter very smartly.

As these cars don't have an accelerator pump there's no point in pressing the pedal a few times before starting.

Can anyone suggest a way of getting past this 'not enough choke' issue?

I don't want to do anything drastic as everything's fine within a minute or two.

Have you tried less choke at all?? You might be flooding the carbs when you blip the throttle so worth trying it maybe?

same carbs same issue, although I just allow mine to warm up a bit and then very gradually increase the throttle until it revs higher then seems to be ok after that.

Taking it to Boggs in the next few weeks and was sort of hoping this can be sorted then but seems like if we both have the same problem it may be "by design" is how Microsoft would call it.

Cheers

Rich

i have the same carbs as david, runing on a 1.6 pinto, and i pull out the choke all the way trun the key and it starts, tick over slow at first, but once it the revs pick up, i just push the choke in and back out of the drive and go out, and it fine.

stuart

Paul - no, it's definitely 'not enough' - in the summer if I leave the choke on too long it starts to cough and splutter, but it still runs.

Richard - I'd be interested to see what Bogg Bros say!

Stuart - all I get is half a tickover! It's barely enough to keep the engine turning.

My guess is that the starting enrichment control is designed for the 600cc engine, and that the x-flow is sucking too much air in to get the right starting mixture. I think I'll research the SE mechanism (I've got a manual somewhere on my PC). Maybe I can help it along a bit...

Hi i have zx9r carbs fitted and i dont use the choke at all i just keep trying the starter 2-3 times till it fires it some times pop's a bit but after that it will be ok all day once run
My engine was set up at Bogg Brothers
Jacko

I have the answer David. Injection! Sorry couldn't resist it . How do chokes work on bike carbs ? Do they close a flap ? lower the main jet like SUs? rotate a drum to expose a port ? or operate by other means?

No - just a drip feed of extra fuel into the venturi.

Bigger drip?

Who you calling a big drip!

...and it may be possible to increase the flow somehow. Time will tell!

My pinto is on zzr1100 carbs and is
exactly the same in this cold weather.
starts first turn on half choke and then i let
it warm for a couple of mins.Push the choke home then its fine.

Andy

Once mine's got over the almost-at-a-tickover phase it's fine - it just needs a tiny boost for 30 seconds to get it there.

would it be possible to fit something to increase the idle speed untill engine warms up a bit.you could try screwing tickover screw in half a turn to see if it helps. m.

david, as well mine are heated, so i do not know if that makes a differance to cold starting. the ticks over a 400rpm then increase quickly.

stuaty

David, I have exactly the same symptoms with my Fazer 600 carbs.
Like most of the others I have found that letting it struggle along for 20 secs or so is necessary before I dare touch the throttle, then it's ok for the rest of the day.