Why doesn't my ZX6R like starting?

byke95 · World Chat Champion Joined: 25 Mar 2004 Karma :

Hi,

The bike starts /ok/ in the mornings, doesn't like a lot of choke at all but usually starts on second or third attempt.

[My starting technique on cold days like these = (1) Full choke (2) choke back to half-way once bike starts (3) work choke back to 'off' as bike warms. Basically I follow what's in the manual]

Once the bike it warm (e.g. I stop at the shops or get some petrol during a journey) it's the same thing but slightly worse; it'll take 3/4 attempts to get the bike started.

[My starting once worm technique = (1) ignition, no throttle]

Why is this happening? For anyone who doesn't know the bike fell off the side stand just after I bought it, could this have something to do with it?

It's a 2000 ZX6R with 11.5k on the clock.

Thanks Thumbs Up

Phil

finpos · World Chat Champion Joined: 13 Sep 2005 Karma :

Try "some" throttle when warm starting. "Some" being a bit tricky to define, and varies depending on a number of things.

How old is the battery? It may not have as much ooomph as it did once.

And when was it last serviced?

finpos.

byke95 · World Chat Champion Joined: 25 Mar 2004 Karma :

Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

byke95 · World Chat Champion Joined: 25 Mar 2004 Karma :

Walloper · Super Spammer Joined: 24 Feb 2005 Karma :

Start on Half Choke when it's warm.

An engine needs a slightly rich mixture to start hot or cold.

The choke enriches the mixture for starting by reducing the amount of air drawn into the engine when cranked.

If it floods:

Close the choke (OFF).

Hold the throttle wide open.

Crank the engine several times.

Close the throttle.

Half Choke.

Try again.

You WILL flood the engine if you give it any throttle whilst cranking.

This has the same effect as choke.

The bike should start 'off the key' without any tweeking, fiddling or feltching.

Service the ignition system, Check the Air filter.
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byke95 · World Chat Champion Joined: 25 Mar 2004 Karma :

Walloper · Super Spammer Joined: 24 Feb 2005 Karma :

The bike should start 'off the key' without any tweeking, fiddling or feltching.

Service the ignition system, Check the Air filter.
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DynaMight · World Chat Champion Joined: 27 Oct 2004 Karma :

My 1999 ZX6R was quite tricky to start, needed to be done a certain way.

When cold it's half choke, throttle open slightly to start, leave it at that (should idle around 2k rpm) until it's about to die, then gently keep the throttle open so the revs remain at about 2k rpm then turn the choke off totally, keep the revs at 2k for maybe 10-20secs and let the throttle off slowly. it should then idle fine, they maybe slightly low but it shouldnt stall
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Pete. · Super Spammer Joined: 22 Aug 2006 Karma :

Walloper you should never need any choke to start a warm engine. If you do, it's because you have a problem that is causing not enough fuel to be delivered at cranking RPM to fire the engine up. Either the engine is poorly maintained, low on compression or has some other fault or because the carbs are worn out, faulty or poorly set up.

There's not a lot you can do to service the ignition either on his bike, bar changing the plugs. It's not likely to be an ignition problem anyhow since ignition problems usually manifest themselves are mis-firing or as poor cold starting, not poor warm-starting.

His bike does not have a "choke" that restricts air flow to the engine. Some bikes still use this method but it's very old-hat and not in common use today because modern CV carbs already have that restriction by way of a throttle slide. His bike has a "fuel enrichment circuit" that adds fuel. It's still called a "choke" by most people (myself included) but that's not what it is nor does it work as you describe on the zx6-r.

Cranking the bike with the throttle open won't flood the engine either, unless there is no spark/ poor compression or some other fault and you crank it for a very long time without starting. It certainly won't flood it in a few seconds because the CV carb won't lift the metering needles enough at cranking speeds to allow the fuel through. You need constant engine vacuum to lift the slides and hold them open and you will only produce that vacuum once the engine is running. If you could flood the engine by cranking with the throttle open there would be no need for an idle circuit all the metering would be done through the needle jet.

byke95 your problem could be either a very rich idle mixture or a very lean one. If you turn up the tickover slightly and it starts better you are too rich. If you use the choke to start when warm you are too lean. This is one situation where altering the mixture via the screws is actually an appropriate thing to try, since your problem is with very slow running.
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132.9mph off and walked away. Gear is good, gear is good, gear is very very good Very Happy

Walloper · Super Spammer Joined: 24 Feb 2005 Karma :

Ah meant service the ignition system ie. Plugs, Leads, etc not set the Points gap. Christ... Laughing

You're dead on the money with the rest of it tho.

I know we enrich by other means than 'choking' the inlet.
Is it not the same principle but via different means.
Engines have not changed radically since Jimmy Auto invented the buggers. They still use air, fuel, compression and sparks.

Not wanting to fall oot wi embdy.

But if it canny start off the key and ye canny understand why. Read the book or pay a mechanic.
Or faph about on here. Laughing

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