Carb icing or not?

[Drew]

I've searched and found THIS which is exactly the same problem as I have.


Start up, and it idles fine.

If I slow in traffic or for a junction, it stutters as if it is running on 3 cylinders, (have to dip clutch and rev it to keep it alive) but once the revs are up again, it takes off again.

Everytime I slow to a stop, it cuts out. (starts up totally fine again)
Tested, and when on the move, if I dip clutch, the revs drop and it cuts out. (let out clutch to jump start again)


In the thread I linked to, Keith says it isnt carb icying, so what is the problem, and how to fix it?

ps, bike is 98 gsxr srad.

[MaybeGuy]

ive got the same bike, same problems.... yes, its carb icing.
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Kickstart wrote: Hi I tend to agree with Matt. All the best Keith

[Whosthedaddy]

Had it a couple of times this year, bikes fine until slow down or pull up at some lights and its like a bag of spanners.

[Kickstart]

Hi

Does it fix itself if you stop for a short time?

All the best

Keith
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[Drew]

I gave up on my journey, and returned home. (only went about 15 miles, most of it hoping I didnt have to stop at a roundabout). It cut out at end of my street, but once I pulled onto the drive, it idled fine again.

[Whosthedaddy]

Mine continued for the next 5-10 minutes I suppose of stop start riding.

I've been in colder and damper temps with no real problems?

[Drew]

I remember the same happened to me last year, just after Christmas, I had to keep pulling over, let it cut out, start it it up again, then it was ok for a mile or so, then next junction, back to sounding like only 2 cylinders were working.

Been fine during the rest of the year, its only happens around now.

[sickpup]

[MaybeGuy]

[Kickstart]

[andys675]

buy some silkolene pro boost and say goodbye to icing

[Drew]

So what is the problem if it isn't icing, and more to the point, how can I fix it?

I tried a little choke, it stopped it cutting out, but taking a roundabout at 4000 revs (with no throttle) while braking didnt feel too safe


As Sickpup says, high revs, high speed, there is no problem

[Kickstart]

[Drew]

I know nothing about how carbs work, but i take it from what you say, there is a jet for idle and slow moving, and a different jet for higher revs?

The idle jet is getting blocked or so in the cold weather, but the other main jet is not having the same problem?

[Kickstart]

Hi

Carb icing problems come from the water vapour in the air freezing and building up in the carb. That might block a jet or jam the slide.

On a CV carb (ie, most carbed 4 strokes) the mixture for most of the rev / throttle range is controlled by the needle jet. The needle part of this is mounted in the slide, and the slide moves itself depending on intake vacuum. More vacuum means the slide moves higher, meaning a narrower bit of the needle is blocking the jet. So if the slide sticks higher up then the mixture will be FAR richer.

All the best

Keith
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[sickpup]

Thing is the SRAD has the carbs in a pretty good position to take heat from the engine to prevent carb icing.

As Phantomtek discovered they have tiny little filter in the fuel hose where it joins the carb that block up very easily, no one ever changes them.

Worst of all they seem to be a bike that everyone pisses about with so the fuelling is never right which causes a lot of problems.

I hate it when it gets cold, every running problem gets put down to carb icing yet none of my bikes seem to suffer from it no matter how cold (or moist) it gets.

[D O G]

Since it was my thread to start with, I'll tell you what was acutally wrong with the bike (after much investigation, part changing etc). The fuel pump cutoff was dodgy, which meant that it kept pumping too much fuel in on low revs, but ran fine at high revs as the fuel was needed.

This caused #2 carb to be flooded all the time, as it is nearest the fuel inlet pipe. The problem became progressively worse until it wouldn't run at all at low revs, became impossible to start and it went to a garage and someone who knew what they were doing looked at it.

Think people (like me) like to blame carb icing, since it is one of those 'phenomenon' problems, which is an easy explanation for shit running, when in fact there is just something wrong with the setup or a faulty part in the bike.

I'll say this though, even after it was fixed and apparently setup on a rolling road it ran lumpy at low revs. My 91 FZR 600 pulls smoother than the SRAD ever did. I don't know whether this is a common problem with the bikes, or that the skills of setting up a carbed bike are dying.

[ben_wheely]

I have this problem too (DRZ 400). Only on really cold nights/mornings, it cuts out on low revs/idle, but rides fine once moving.

When it cuts out, its pretty quick to start back up again - providing i give it some throttle.

Changed my plug last week, and noticed that my bike is running rich. But i had a slightly corroded HT wire, so that may of been the cause of my black spark plug.

The HT wire was cut back to a good bit, and a new plug fitted, and still in the cold it cuts out ?

Oh, and by the time i get to work (20-25 mins of town riding) it idles fine ?

Is this carb icing ? Sorry for hi-jacking your thread.
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Rides: '05 Yammy WR290-F

[Kickstart]

Hi

Could just be that it is lean at idle. Carb icing is highly unlikely to be the cause if it happens from cold, as carb icing is caused by air / fuel taking the heat from the carb body, so that water condenses and freezes on the carb body. Hence it needs a bit of time at a fair speed before the problem will occur.

Would probably only take a couple of minutes of low speed riding / idling while blipping the throttle to clear the icing as well.

All the best

Keith
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[NiteMare]

slightly off angle here ....

the only time i've ever experienced carb icing was in an old volvo 145 estate, single stromberg carb on a 2litre push rod engine, it turned out that water had collected in the airbox to carb joint and as the airstream was flowing over it , it sucked vapour over the jets which then solidified ....

of course we'd pull over going WTF!! and it'd start again within seconds, which had us baffled for a day or so (engine heat melted the ice)..

i eventually started to take things apart to try and suss the problem and spotted the puddle (about 2 tablespoons full) drained that off and the problem was cured (luckily it didn't spill without me noticing or i'd have hunted for quite a while and took more to bits than needed)...

all this was in the early summer, i've no idea how the water had got there but once it was gone the problem was solved
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it ain't broke...

i ain't fixed it enough

[Drew]

[Drew]

[sickpup]

[Drew]

From what I understand......

Arrow exhaust
K&N filter (doubt it does anything, but was in when I got it)

i also believe it has some timing advance plate on there, as I got one given when I bought the bike with the other parts, which I assume is the standard one.

[Kickstart]