big bang help

[Val]

Hi guys,

today was cold. My FZS 600 was not starting even on choke. I have tried about 20 times. My battery is good and I keep the bike on a charger.

I have used such pattern - I try 3 times no wait between the times than wait about 5-10 seconds and try again.

There was distinctive smell of gas. I may have flooded the engine.

Than after on 21sr try after one of the big wait I hear really big bang. Louder than a gun shot. Next try it has started on choke.

Than the same thing has hapenned on the way home after work. Many tries in the work car park followed by a big bang and starting.

Any ideas why this bang is hapenning? The bike is over 30k. I have no idea are the carbs ballanced at all.

The bangs apparently has loosen up the last bit of the exaust the can with the muffler?

The exaust can got disconnected from the single pipe somehow messed with my back wheel, the feeling was like somebody kicks your bike rear tyre. I also lost it because of that when filtering 1 mile from home 

Luckiliy the place was with 3m wide shevrons so I have fallen down gently there. Nice guy has helped me to pick the bike.

The exaust peg connection was still holding, I have tried to move the pipe out of the way. This time the bike started fine the first time on choke.

The sound was funny, everybody was going out of my way the moment I squeeze the clucth because of the screaming sound and I've got home slowly. 

Any ideas about the big bang?

[BBROWN1664]

fuel in the exhaust from the failed starts will eventually go bang.

[chaz]

I think that the plugs spark every time the pistons are at the top so if it doesn't fire on the power stroke the fuel mixture is pushed into the exhaust and can fire on the exhaust stroke.
If your bike isn't starting on the button then there's something wrong, could be what you are doing, e.g. too much choke or not enough? I've a FZ6 so just turn it on and press the starter no throttle and as long as the battery is ok it starts. Mine has over 45K on the clock.
When was the bike last serviced? has it had new plugs? is the air filter clean these are what I would check first, is the battery spinning the engine over fast enough? then work your way through things like carbs, plug leads ect.

[darrsi]

Why you suddenly talk like China man, Val?

[unfazed]

Loose plug caps on the leads can cause it and it is the cheapest thing to check first.

[celticdog]

Why you suddenly talk like China man, Val?

   Me so velly solly!

So the misfire's on the exhaust rather than the intake, you've got a rich mixture so it's not a vac leak. TPS? Could it be an exhaust leak- what condition was your exhaust in before this happened, has it been sounding rough lately? It looks like you've got lots of things to look for 

[chris.biker]

Hope you get it sorted.

 

[darrsi]

May have water in the carbs/tank?

[Val]

Why you suddenly talk like China man, Val?

   Me so velly solly!

So the misfire's on the exhaust rather than the intake, you've got a rich mixture so it's not a vac leak. TPS? Could it be an exhaust leak- what condition was your exhaust in before this happened, has it been sounding rough lately? It looks like you've got lots of things to look for 

Me solly fol the lovelly talk 

Anyhow thank you all

The spark plugs are new and the filter has been changed last week with K&N

The exaust has sounded weird for a while

I have some work to do now 

[darrsi]

Still think water in the carbs could be a possible culprit, i'd be inclined to drain a bit out of the carbs to see if there's any water present at all.

[Val]

Still think water in the carbs could be a possible culprit, i'd be inclined to drain a bit out of the carbs to see if there's any water present at all.

I was afraid you're gonna say that 

Last time I have opened carb was 30 years ago...or there is just a drain hole hopefully somewhere there?

And I need to read the manual as well  honestly I just want to ride the bike 

I may need a mechanic here, anybody of you guys that can recomend great mechanic in my area? Bracknell, Reading, Wokingham?

I know a garage called http://www.keithmanningmotorcycles.co.uk/

Any feedback about it?
 

[unfazed]

Water in the carbs would not cause the bang, but would cause slow starting (water does not ignite
When the bike is sitting overnight water sinks to the bottom of the carb bowls and is picked up first by the pilot jets and will run through them first mixed with a little petrol but will not ignite.

Take of the plug caps and try and tighten them (clockwise) on the leads if they are loose there is your problem