Engine rattle 800XC

After 35,000 completely trouble free kms the engine on my XC has developed a rattle. I first noticed a slight tapping like a loose tappet when i got home last Friday. Being in Mozambique I do all the servicing myself and the only thing not done is the electronics download for faults and electronic checks. So I thought it was time to check shims but when I started it on Saturday morning it sounded like a stone being rattled in a tin can. I checked all I could and took a chance and started it again. After a while the noise lessened but did not go away. If I blipped the throttle it rattled worse as the revs dropped. After letting it idle longer the noise stayed much the same.

Just to be sure I changed the oil (only done 4000km) and filter, cleaned pre-air filter, checked the timing chain tensioner (OK)  but the noise was still there. so I left it to try and figure out what could be wrong.

This evening I started it again and it was back to a tin-can rattle. It seems to be louder on the right hand side. I have been searching websites but cannot find an explanation!  I don't want to take a chance and ride it back to Durban or Jo'burg to agents, and to arrange transport for it is a hassle (plus the long cage drive to get there and back).

Any one had a similar problem - or any thoughts on where to start looking?