Starting Issue

[JoeRock]

Got a bit of an odd starting issue guys, was wondering if I could have some suggestions as to possible causes:

Basically, the bike is proving to be an arse to start in the morning after its sat over night. It churns over fine on the button, and the battery is good (99.9% sure on that - used a trickle charger on it, it didn't charge for long before it said it was topped out, and the battery spins the starter motor over for ages).
It spins over for a while, and then eventually starts - when it does, there is always quite a loud "BANG" from the exhaust.
Once its started, it's fine; it runs completely normally, and I can turn it off and on again and restart it as many times as I want - it's just the initial starting that's a PITA!

Now that's the "always" route, I'm not sure whether this is connected or whether it's coincidence, but the three times it's done this now I've tried to start it for a while, it won't start, I turn the ignition off and on again and then it starts with its exhaust bang.

So, any suggestions as to what I should be looking for?

[red98]

sounds like sparks to me.....the bang is the fuel igniting in the exhaust,churning over the engine is pumping fuel through the carbs,combustion chambers and into the exhaust,then a stray spark is igniting the vapour in the exhaust.....when was the last time the spark plugs were changed ?

[CRH]

think you will find that the bang is unburnt fuel ignigting in exaust cus of the amount of revolutions from engine before it fires up!!...just petrol in cylinders!!...has for not starting very well?...sounds to me like you over choking it?....try with no choke first and just slightly feather the throttle when/if it fires?

[darrsi]

What about a TPS check?

[CRH]

What about a TPS check?

....oh yes ...i concur" ..f,got bt that?

[JoeRock]

To answer your respective points:
1.) Not very long ago, I changed them when I changed the spark plug caps, so I think maybe a couple of thousand miles ago? Off the top of my head I think that they're 8EIX ones (iridium, NGK, I used the ones recommended in the Haynes manual)

2.) I haven't ever had to use the choke to start the bike, just push the button and it starts - that method has worked so far in my ownership until now? Can imagine having to use the choke a bit more when it's colder, but we've not really had a massive temperature drop in the last couple days and it's just acting up now.

3.) TPS check I'll do as soon as I'm home, what was the procedure for that again?

[JoeRock]

Turn on igition, disconnect and reconnect TPS - if it sits at 5k revs then it's okay?
is that basically it? And if it's at 10k, adjust it until it sits at 5k?

[darrsi]

Turn on igition, disconnect and reconnect TPS - if it sits at 5k revs then it's okay?
is that basically it? And if it's at 10k, adjust it until it sits at 5k?

Can go either way, 0k or 10k but yeah you want it on 5k.
 
If it goes to 10k don't switch key off.
Either adjust straight away, or start engine before switching off, otherwise the needle will drop clockwise then you'll have to have the clocks apart.
 
 

[red98]

take the plugs out and see what colour they are..golden to dark brown would be good..fazers run a little rich hence the dark brown  ....as you`ve been trying to start without starting i expect the plugs to be wet and black.clean them up and pop them in the airing cupboard overnight to dry out....just dont tell swmbo   

[Fazerider]

Mine developed the same symptoms in late autumn a few years ago... I'd never needed choke to start it and, when I tried applying it after the starter had turned the engine over for a while without success, it made matters worse by flooding the engine.
One morning I decided to try setting the choke half way and then hitting the starter button and it fired up immediately.
I've no idea how it goes from being too lean without the choke, to flooding with it, without going through a point where the mixture is ideal, but applying choke before touching the starter made all the difference.

[His Dudeness]

The bike's scrap I'll give you a tenner for it

[unfazed]

Thats  the sympton of loose plug caps.
Remove the caps cut about 10mm off the leads, spray with WD40 and screw them back on and reseat the rubbers

[JoeRock]

Right, done a few of these now:
TPS check came back fine.
Pulled the plugs and compared to the haynes manual - they look pretty much spot on, perhaps a tad edging towards the wet side of things but not far off the ideal picture (I do have a K&N filter and aftermarket exhaust though!).

Weirdly though, it's now running fine again! I suspect I may have potentially been flooding it with too much choke - using about half and hitting the button seems to make it fire up perfectly, each and every time!

[Lawrence]

Dirty ignition switch. Squirt loads of contact cleaner down the key hole, stick key in and turn on/off a few times. Had the same with mine before after it sat out in the rain all day. Span over fine but wouldn't try to fire.

Bang from exhaust is because even though it's not getting spark, the air flowing through is still pulling in fuel and it ignites in the exhaust when it finally fires up.

[john 087]

same as above. had the same problem.

[Captain Haddock]

Chances are contact cleaner down ignition barrel just strips lube out of the barrel and gets no where near contacts, leaving you with a worn out barrel and still dirty contacts, I would check all connections under the tank and neutral light/side stand switch, failing that clean carbs and check float height.

[Lawrence]

I guarantee that's what fixed mine.  After determining exactly what it was (when it failed to start tried wiggling steering, then kill switch, then key, trying the starter after each thing) and cleaning the barrel it's not done it once.  That was over a year (20k) ago now.