Missfire,cranking noise!

[Shon]

Hi guys,
listen to this...

Bike works wery well,i have no conplains.But there is one thing.
When i leave it in neutral and give it just a little twist in the gas ,and keep it on the 1900-2100 rpm ,there is a moment when it makes a cranking noise for a secend and it seems that the gases that should go out through the exaust pipe go back to the carbs for that secend.

i was thinking it is a mechanical problem but every part of the engine is perfect,like new,the cam chain,the sprockets,the cam chain tensioner, everything checked.

So i took a stroboscoup and found out that the left cilinder doesent get the spark on time, like it missfires and that is the thing that makes the strange noise and the gases dont flow right.

But i am not sure if it can be just a bad contact somewhere or the left "bobine" (dont know how you call the thing that makes electricity for each cilinder) or some other thing.

Does anyone have a clue??

[The Buddha]

OK 1 cylinder not getting spark at a specific rpm ... OK aux ground ... actually 1 cyl anyhitng electrical = aux ground IMHO ... first stop ...
Cool.
Srinath.

[Shon]

Can you please make it  littlebit more clear to me?

[The Buddha]

From the bettery negative, there is a fat wire and a skinny wire. That skinny wire goes into a plug of sorts ... that plug not making full contact ...
Cool.
Srinath.