Freezing wide open.

[Grooveski]

Hiho,
I'm new here but have done a couple of searches and couldn't find anything so thought I'd ask:
Anyone ever had problems with their carbs freezing wide open?

Three times over the years I've backed off the throttle and it hasn't responded. Once was just a stutter and I was expecting it but the others were two of the most worrying moments I've had on two wheels.
Same conditions each time. Early winters morning, dryish road but light freezing fog. Back off to drop into corners at the end of long open stretches but the revs don't drop and you have to clutch and kill switch then act like you've seized a wee two-stroke and stand around/have a fag 'till the carbs warm up enough to free up and work again.

Every winter for quite a while I've cut the bottom inch or so off a couple of plastic cups from water dispensers and stuffed them into the airscoops(they fit a treat) then pulled them out in spring.

I'm not imagining it. The time I mentioned that was only a stutter(the last time) was while testing the theory. I hit a quick stretch in the right conditions, had the freezing occur then stopped, blocked the scoops and carried on in the same conditions with no problems.
It's not just the cold, have run in colder conditions with no problem. It's the cold and mist together.
Not like normal carb icing either(stuttering out the village syndrome - never had it on the zxr but know it from other bikes), every time the engine was up to temperature and I was well into the run.

My carbs are the Keihin 33mm flat slides. They have their quirks in normal road use but nothing you don't get used too.
...apart from barreling into corners with the throttle jammed open on freezing mornings sometimes.

[RedexRobB]

Have u got the throttle return cable Fitted? That alone should close the throttle.

You can fit heated carbs and see if that helps they are fitted to some but not all zxrs. You will need to get thepipe work that's needed to run the coolant from the cooling system.

[Tirpitz]

I'm not convinced this is carb icing in the traditional sense, as that usually blocks the jets and leads to poor running, as you have experienced with other bikes yourself. It may be that the carbs are sticking as a result of the low temperatures but if you have a throttle closing cable fitted I find it hard to imagine the carbs sticking so solid that the tension of a cable would be unable to move them.

Of course if you have no closing cable fitted it answers a recent thread by someone else as to why it should be fitted as the spring is not always enough in extreme conditions.

[RedexRobB]

I think ur right tirpitz its not carb icing. Probably a sticky cable.

[cargo]

I would agree I dont believe it is carb freezing either............that causes poor running.

Also we are talking about flatsides here..................Kawasaki never fitted carb heating to them.

If I was you I'd have those carbs off in be inspecting them for wear or damage................I do know that on road going ZXRs with flatsides wear can occur because the slides bounce around at tickover and road bikes spend a bit of time there............... fixable but not easy.

Also I recently found a broken bit in the slide lifter mechanism in one of my carbs along with a an adjuster screw that had come loose on another carb in the same set.

I would suggest a full and very carefull inspection of the carbs internally as well as externally and operating mechanism. And the TP sensor too for that matter

[Grooveski]

Funnily enough that's the job I'm just getting onto, a couple of the slides are a lot looser than the others, the pilot needles are worn, the mains have had someone in at them with the wrong screwdriver by the looks of it......
Not opened up the slides and needles yet but yeah, definately refurbishment time. That's why I was trawling the web and found zxrworld.

Long time since this happened though. Bike only had 10,000Km or less on the clock.

It's got a return cable fitted but while it certainly felt like a stuck cable it didn't really act like one. Both the bad times I waited a few minutes then it freed up of it's own accord.
I've only just changed those cables too after thousands of miles and no other moments.
I did wonder at the time about the little slider that ties the carbs together, whether ice could build up in the slots.

Either way as I say it's never been a problem since. I'll just carry on blocking the scoops in winter. Doesn't affect the breathing any, only means I don't get that crisp winter's morning power advantage since it's sucking in warmer air from round the engine.
Was really just wondering if it was a common occurrence. Glad to hear it seems not.

[Grooveski]

Was ordering fresh O-rings today from Allen Performance and while pricing the replacable bits of the slide and discussing if mine were excessively worn he mentioned that one of the symptoms was the carbs sticking wide open.
I said I'd had that a couple of times but only in winter.
His reply was "Bitter morning? Freezing fog? No, that can happen anyway with those. This'd happen anytime."
..."duckie."

Which kind of figures. Was still a pretty fresh bike when it first happened to me.
Just thought I'd post an update as if our friendly neighbourhood Keihin stockist knows about it it'll not just be my bike.