Hi all, im trying to make some exhaust protectors from carbon. i now made 20 of each and only 5 of them are good enough to use. The problem i run into is that all the flat area's are fine but 2 spots where 2 bumps are, always fail.

The material is bridging. You need to either cut the material as a disc and match the next ply. And you need to force the materila into place under vacuum. The vaccum bag alone will not make the material confirm to that geometry

Yeh, gotta sort out the bridging. It's tricky geometry for a twill fabric to go around easily, so it can be difficult to force it into place without pulling it out of place elsewhere. 

Both the suggestions are good and may work.  However you choose to try, the key thing is ensuring the material and bagging stack do not lift from the mould surface.   I would favour a cut disc out of the cloth for this one, then overlap a second piece of cloth for the recess.  There is less surface distortion of the main piece of cloth that way as you are not trying to force the cloth into a raised feature.The inside of the raised feature when demoulded is unlikely to be so visible that it matters if the weave on that piece has slight distortion.

Warren Penalver
Easy Composites / Carbon Mods - Technical Support Assistant

From your pictures I could see that you've got some pinholes in the flat areas too. From my experience this is caused by unpropperly degassed resin. But there have been a similar discussion before, and most people here think degassing does not effect the visible quality of infusion parts at all. But from all the research I've done, I am pretty sure it does.