Big bang

[Syborg]

Hi all

The mighty Bros is giving me some worries at the moment. Quite often (well in the past month) when the morning is cold there is a big bang coming out of the exhaust when I hit the starter button; it can happened a couple of times before it starts running.

Now a strange noise is coming out of the top of the engine when I increase my speed, and it will stop suddenly (the noise not the bike) when I come to a stop. Thats started a couple of days ago

I've had a look on the web and a Kawa website mentioned it might be down to the valves getting loose.

Any other idea or would you confirm valves clearances? (which haven't been done for 25k kms) Is it safe (ie not doing too much harm) riding the bike?

Thanks

S

Edit: Heard the Noise again tonight, only at high speed and it sounds like a supercharged bee

[Mr.Pigdog]

Hullooo,would say it's unlikely to be valve clearances(clearances reduce over time not increase-thus getting quieter if anything)sure its not a exhaust header blowing???does it sound like an ignition backfire kind of bang-or a mechanical bang??

[Syborg]

I would say ignition. It hasn't started as well as it used to recently, taking few seconds before firing up (or farting loudly). Thinking about it only happens when it's really cold in the morning. I don't touch the throtlle when I press the starter but have full choke on. The bang is like a big gun shouting, scary!

[Mr.Pigdog]

First thing i would do then is check the state of your sparkplugs-should be a nice coffee colour-not too black-ensure they're not loose.Plug them into the plug caps and check the colour of the spark is nice,strong and blue rather than orange against an earth on the engine.

Are you only doing short journeys in the morning and its not getting off the choke-maybe sooting up the plug??

[Syborg]

I was thinking about the plugs too. Also got the advice bout the exhaust from someone else so will check that out too. My commute is 14 miles and I only use the choke to start it.

I will have a go at the valve clearances anyway, I have no idea when was the last time they were checked.