Divvy 600 will not idle. Carb icing?

[knocker]

Went to start the bike to go to work at 5.30 this morning and although I can get it to start it will not idle at all. If i leave it ticking over with the choke open then it will idle rather roughly for a few minutes before stopping, if i close the choke then it dies immediately.

I have just been out now and run it for a good half an hour to get everything hot and although it will now idle with the choke off, it seems very very lumpy and the revs keep dropping to around 500 before picking up again.

If I rev it then it seems fine over 2000 revs althoguh it does seem to be taking a bit longer to pick up when i give it some gas.

I'm hoping it's just the cold that's causing the probs as i really can't be doing with going to work in the car as it's a £7 per day round trip as opposed to less than £2 on the bike.

Anyone got any suggestions?

[Pete.]

Mine was like that until I set the float heights and balanced the throttles. It would also rev to 2000rpm in neutral when it was warm, but turning the revs down caused it to stall when cold. Doing the two things above cured all of it.
____________________
a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[knocker]

I have considered this although I'm leaning more towards the possibility that the carbs are icing as it has only just started happening since we got the really cold weather (it was minus 5 this morning)

[knocker]

It seems to have done it again this morning. Was fine when I first started it and was okay for about 2 miles before it started to feel weird and began to struggle. Same symptoms as before, if i let go of the throttle the engine dies straight away, it was misfiring and just generally shite under about 3000rpm, any higher revs and everything seemed to be as normal.

Looks like i'll be getting my spanners out this weekend.

[Coxyzxr]

[iooi]

Here is what you need to do......

I got to do this myself as i have the same problem. Its done this before when cold, so its a known cure

Remover tank and open air box.

Clean all the crap out. Odds on its got loads of thin oily liquid in it. Guess this freezes in the idle needle....
Take crankcase breather pipe off and clean out.

You may have to do this a few times over winter if you do short runs.... I do 20 miles each way and it still does it after a month or two.

I guess best soluition is to find somewhere else for the crankcase breather to vent. Toying with the idea of some form of filter to allow air to escape, but hold the moisture and vent it to the rear of the bike.
____________________
Just because my bike was A DIVVY, does not mean i am......

[Coxyzxr]

[iooi]

Plenty of pressure from the crankcase with the pipe not connected to the air box. But i take your point.
Might just see if i can fit something in-line to catch the worst of the moisture and the dammed white gunk.

____________________
Just because my bike was A DIVVY, does not mean i am......

[Ichy]

[Coxyzxr]

[Ichy]

Most bikes I've worked on haven't had a valve on the breather, those that did have a valve used them inline with the breather pipe.

One way valves are just as likely to work on positive pressure to force them open.

I have no idea about negative pressure valves on bike crankcase breathers, just that I've fitted loads of bikes with pod filters and never had a problem. Maybe I'm lucky?
____________________
https://www.metacafe.com/watch/1972097/how_to_behave_on_a_forum/

[Kickstart]

Hi

I am with Ichy on this. Pretty common to dump the airbox (although not a great idea for other reasons).

Not sure the amount of moisture in the crankcases is enough to make carb icing worse. To be honest never even thought of it. Possible I suppose, but you could also argue that the warm air venting from the engine will help prevent carb icing.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[sickpup]

[Coxyzxr]

[Kickstart]

Hi

While in theory true, in practice I would suspect for any vaguely healthy engine the effect would be pretty much irrelevantly small.

All the best

Keith
____________________
Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[iooi]

Well took it apart today and there was a good 1/4" of thick (was cold) liquid at the bottom of the air box.
So that getting into the carbs would mess up the idle jet.

Cleaned it all out and she now runs as sweet as anything.

Plenty of pressure coming out of the crankcase breather, so venting elsewhere is not going to be a problem. Have placed a inline moisture trap for now to see how that improve's running while still connected to air box.
____________________
Just because my bike was A DIVVY, does not mean i am......

[sickpup]