After a trial I have black goo dripping out of the joint between the middle and end piece of exhaust. any ideas why and should I clean out centre section. if so, how

Hi

Just to avoid any misunderstandings, the specific bike is?? (your Avatar says Gas Gas and this is in the Beta forum).

Dom

You need to re pack your silencer. Cleaning the centre section will help but the goo you notice runs back down form the silencer and not as much up from the centre section.

By a big bag of packing material for a couple of quid and change it once. Ride the bike fast on trails for and hour or so (use 50-60:1) and then this helps burn the header and centre section off.

Once cooled change your silencer packing again.

Not a proper job such as using spuds and caustic soda but it'll help.

The black goo is just old un burnt oil in the petrol mix that has migrated through the pipe and not been burnt off through hotter exhaust temps.

Thanks Dom Bike is now a 2008 Rev 3. . I will change Avatar

There is also O rings on the joint between the two boxes You will see them when you remove the tail box to repack it these go hard over time and break so do not seal

Edited January 6, 201313 yr by naichuff

Ok. Will order 2. Cheers

Wash out the old oil first.

Before repacking slosh some petrol inside the removed pipes. stand it on end to drain and leave over night so the petrol can evaporate.

WARNING risk of explosion....... so let it evaporate and then REPLACE the packing material.

How do I remove the old Packing and Why is it necessary to replace it if the noise levels are OK?

Remove the the outlet end there is two screws holding the black end on

This will remove the baffle tube.It can be tight to get out but watch the box is very thin Remove any packing left inside and repack Just done mine and there was very little inside to remove It may take a trial or two to settle but it will change the peformance of the engine.

The packing is like a sponge but through capillary action not pore spaces . It absorbs lots of oil over time and becomes saturated. It then drips out hence it does it when the packing needs a change. Leave it longer and the soaked packing breaks up and then it gets noisy.

Silevcer stripped and cleaned. How tight should I repack it.

As tight as you can get it is what I did. I used the matting material and wrapped it tightly as poss. I then filled any corners with the off cuts - I still have a bit left over for next time.