VL250 + Cold weather = poor idle, black smoke, sometimes flames?

[stanleychung]

I wonder if anyone with better expertise can offer some advice of what i can do in this situation. I've got a 08 VL250 with about 6k on the clock and in the cold mornings I get the same story almost daily, about halfway through my journey to work.

Poor idle and this morning i had black smoke and even a flash of a flame in the exhaust. Now i had the poor idle during cold weather issue looked at before by the dealer and they rejetted the carb with bigger jets to compensate and it seemed to cure it but this morning its particularly bad. Especially i havent seen black smoke and flame before and i just look like a dick revving the nuts off my bike when im stopped at the lights just to keep it going.

Choke doesnt seem to help the problem, running higher octane fuel doesnt seem to solve the problem. I've considered plugging one of the intakes (as it has two intakes) to restrict the air going in. I've considered carb cleaner (which is odd considering the bike is so new). Its just recently been serviced.

I might give the plugs a clean later tonight just to make sure its not a faulty plug. I'm really out of ideas. The really annoying thing is that once it warms up or after all this episode and you leave it sitting for a while it all comes right back to normal again. Arrrgh!!!!

[The Baron]

I don't know if this will help but.. some years ago I had a Ford ute that did this each winter morning about 15 to 20 minutes into my trip to work. We fixed the problem, after some weeks of this, by changing the air filter from winter to summer setting. Problem solved.
It was freezing the fuel by taking in to much cold morning air.

Yes - coughing and black smoke.

Good luck.

[stanleychung]

Yes that does help. I'm entirely guessing here but i wonder if that difference between "winter" and "summer" setting basically reduces the intake size. Restricting it from taking in too much air. hmmm. If that is the case i might just find some plugs to plug one of the dual intakes or resize the intake on my bike just for winter running.

[vifferman]

Flames? Kewl!
When you find out what's causing it, let me know. Even better, if you can fix it so there's REALLY big flames out the zorst.

[stanleychung]

Flames? Kewl!
When you find out what's causing it, let me know. Even better, if you can fix it so there's REALLY big flames out the zorst.

Lol flames do look cool but when it is in that state it does run like absolute sh%t. The more i read up about it the more i seem to think that its just the cold air causing some icing up in the carb itself. Which can be lessened by actually properley warming up the bike before i go riding in it or the hard way is to reroute the air intake to pick up air from somewhere warmer i.e behind the engine.

But Im going to try letting it warm up first before taking it for any sort of ride. I might try putting a little portable heater next to the engine block before i set off in the morning lol.

[retro asian]

Had the same problem this morning and last night on my VL250.
My answer, just keep the throttle on at all times

I wonder, would messing with the Idle settings help?
(I'm selling mine soon, so will probably leave mine as it is)

[stanleychung]

Had the same problem this morning and last night on my VL250.
My answer, just keep the throttle on at all times

I wonder, would messing with the Idle settings help?
(I'm selling mine soon, so will probably leave mine as it is)

Yeah keeping the throttle open big when im at the lights just makes me look like a real nut. I've messed with the idle settings before but with little effect. I think what will need to happen is a decent warm up period before setting off.

I dont think we are alone with the cold running problems with this model. After googling for some answers i found some owners in australia who are experiencing the same thing. Poor performance under 10 deg C.

A slight spoiler on otherwise a great product I must say.

[stanleychung]

If anyone is still keeping an eye on this. I found a very unscientific way around it.

Letting the bike warm up to temp before riding helps. I know this is going to start backlash about how you are "not supposed to warm a bike on idle" etc etc but i can't get it running/idling smoothly otherwise.

The initial heat created by the warm up keeps everything toasty while you are on the move so it doesnt cool down too much unless you ride really fast. It doesnt cure it entirely because it still stumbled momentarily at one set of lights but the heat from the engine came back quick and the whole package went back to normal again.

I think i will keep on this technique on really cold days unless someone can suggest a solution that is not a carb heater.

[rickstv]

I have exactly the same problem on my lifan LF250 when I'm riding in frosty conditions. I think the air is too cold in the throat of the carby.
My chainsaw diverts the hot air from the cooling fins into the carby and there is no problems at all.
Bike manufacturers may think we shouldn't be riding in freezing conditions (dont realise how tough we Kiwis are maybe)
Rick.

[retro asian]

If anyone is still keeping an eye on this. I found a very unscientific way around it.

Letting the bike warm up to temp before riding helps. I know this is going to start backlash about how you are "not supposed to warm a bike on idle" etc .

Check the owner's manual.

From memory, i think it says Start with choke (on half) for around 30 secs and then warm up for up to 5 minutes before riding.

Doing that definitely helps (same thing goes on my VL800).
Fuel injection in the newer models solves this.

[stanleychung]

Check the owner's manual.

From memory, i think it says Start with choke (on half) for around 30 secs and then warm up for up to 5 minutes before riding.

Doing that definitely helps (same thing goes on my VL800).
Fuel injection in the newer models solves this.

Ohh i must have missed that in the manual. Oh well i guess thats why the warm up works i guess. Cool sorted.

[marty]

flames and black smoke (too rich) points to carb icing being the likely issue - too much fuel not enough air once ice starts forming.

the winter setting directs inlet air to a warmer place before fuel is introduced, but i'm not sure a bike like that would have it. running with the choke on can actually worsen the problem, as icing happens more often at closed butterfly settings, than at wide open.