Idling issue when cold

[BrKr]

Hi there Guys

I have a YZF1000 Thunderace '97 model.

My bike struggles to idle when its cold, even with the choke on. once the bike has warmed up a bit, idling settles to where it should be.

What could be the possible issue/s?

Thanks Guys

[Easy-X]

Is the choke actually making a difference? I take it you have to sit there like a lemon giving it a little throttle till it warms up? If so, can you hold the revs and toggle the choke...
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[redeem ouzzer]

Is it a bit lean at bottom end on the pilot screws?
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[BrKr]

Easy-X:

Choke helps little, but not much. Hahaha, I do feel like a lemon warming it up, but if I start and go, bike runs perfectly, just got to play with the throttle when I stop, once its warm, all is well.

Forced:

I had the carbs taken in for this exact reason, but apparently carbs are in tiptop shape, all jets are perfect.

[Tankie]

Just screw in the air screw 1/8 of a turn this will richen the mixture at idle, when these bikes leave the factory the lean them as much as they dare.
If you still are having trouble check for air leaks in the area of the inlets and blanking plugs on the carbs.
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[BrKr]

Tankie:

Thanks, will give it a go as soon as I get a gap

[Tankie]

Just remember us a good fitting screw driver , if the pilot air screws don't move you'll have to remove the carbs and use something to free up the screws ,heat works ,but only on dry clean carbs,
NO petrol in them at all !
remove the bowls, gaskets, floats and float needles.
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Always learning, everyday is a school day

[MCN]

To start a cold engine requires excess fuel to enter the cylinder. Excess is required to allow for some of the file condensing on the cold surfaces of the engine where it cannot burn.
The choke is required until the engine is warm enough to evaporate or prevent fuel condensing on surfaces.
Google Carburettor Heating.

Start on full choke and ride off. There is no real benefit in letting a vehicle engine warm up at idle. It wastes fuel and slobbers fuel into The lubricant.
Start the hoowur and go.
Just don't give it 'what's for' until the engine can run without choke. Which should only take a few minutes after you pull away.

Don't fcuk with any carb settings.
There are 4 carbs and they must be balanced to ensure even running. (All 4 cylinders get the same amount of fuel throughout the rev range.)

You need a special device to balance carbs. Or some person who has the tool and skills.
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Disclaimer: The comments above may be predicted text and not necessarily the opinion of MCN.

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[jaffa90]

Some do have air screws,
https://exupworldwide.com/forum/viewtopic.php?t=9093

Don`t let Nobby read ; dragracer1951 June 5th reply!!!!!!

[Easy-X]

I mentioned the choke 'cos that doesn't look like the sort of bike to be reaching into the engine area to piss about with a lever on the carbs. I'm assuming it's cable driven from the handlebars? Maybe the cable's a bit slack.
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Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Fizzer Thou]

The carbs on the ThunderAce have a TPS,which is the only difference between them and those on my FZR1000R.The resistance is easily measured with a multimeter.If the track is dirty at small throttle openings then this can cause problems.

Otherwise,if the air screw adjustment is 2.75 turns out like they are on my Exup as standard,try turning them in one quarter of a turn.This will richen the low rpm settings.

Do you have a non-standard silencer fitted?

Is the Exup valve set correctly?

How old are the spark plugs?

How much freeplay is there on the choke cable?
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