reconnected breather to Airbox and bike started puffing a little blue smoke??

[highspeedjelly]

The previous owner had the valve cover breather vented down a tube running to an exit by the swing arm and the breather hole at the airbox blocked off.Reconnected correctly the bike now gives the slightest puff of blue smoke when hot and give a decent rev.I disconnected it and it stops smoking straight away.The weird thing is there is no oil residue in the pipe and the old one has no oil in it either.Any ideas?

[michael816]

Sorta related but off topic, what does the breather hole do?

[highspeedjelly]

Sorta related but off topic, what does the breather hole do?

Its supposed to be connected to the breather on the valve cover to recycle into the airbox.

[49er]

Its supposed to be connected to the breather on the valve cover to recycle into the airbox.

The reason that the PO was not using the stock breather to the airbox is because the internal track in the top of the airbox is blocked.
When you fitted it back up, it was causing the crankcase and cam cover areas to pressurise. That is why your engine was smoking when it was hot or at higher revs. The crankcase pressure is forcing oil past the rings causing the smoke. It you were to run the bike for long like this, you would find many small oil leaks would start all over the engine. The cam chain tensioner is a prime spot for these leaks.
If you want to use the stock breather system, you need to clean out that blocked track.

[highspeedjelly]

Thanks 49er I will look at that tomoro.