Well, I got as far as work today but my bike has developed a rather terminal sounding rattle from up front. Bike has done about 40k miles, done the valve shims twice in that time, last change about 6 months / 8000 miles ago. Been running perfectly normally in that time.

Symptoms:

Over about 10 miles the engine started to develop a slight rattle, especially noticaeble if the revs dipped below 1200.
Was taking it easy the whole way in - rattle started to get worse / louder
Pull in to work driveway, bike stalls out once RPM drops below 1200.  Won't start again while hot.
Got it up on the stand and it almost sounds like the starter isn't engaging.
Engine seemed to be holding in as long as the RPMs were held up above 1200 rpm

Any quick checks I could do before I consider getting it dragged off to the shop?

Edit:
Looking at if the starter clutch may have borked itself..

On this forum is a few psots about the alternator rotor loosening. That will make the starter sound like it isn't engaging and possibly rattle ( eeek). If it is that, I would be checking the torsion on tha Alt. bolt REAL SOON.

https://youtu.be/GxS5yZ44AHU

cheers for the replies - have looked at a number of previous posts / youtube clips - not the same sound. The starter gear seems to be trying to engage against something, but doesnt appear to be turning the crank over at all.

It's gone to the workshop for a looksie - will keep everyone posted on what it turns out to be (and probably post a clip with the starter sound).

Just have to deal with a +10min extra commute on the green monster (NBC110)...

Quote from: Kiwingenuity on February 21, 2018, 01:59:05 PM

Just have to deal with a +10min extra commute on the green monster (NBC110)...

they make things slower than the GS? 

heh... definately a bit slower  suprisingly the green monster (ala Super Cub) does about 90kph on the highway - when you have no head wind that is...

Well, it's not great news - the clattering sound was a gradually un-tensioned cam timing chain hitting the top of the valve cover.. 

The camchain tensioner spring has let go / eventually snapped..  time for a top end re-build at least (hopefully that's all that needs doing).

Getting the motor pulled out of the frame for a closer look the next few days. Plan B is getting some prices for second hand motors for transplant, but rather have the engine I know than one that is from a wreck if mine can be saved.

update... She lives again after a transplanted motor has been dropped in.

Will re-build the borked motor over the winter here - figure it can't hurt to have a whole spare motor..