exup valve rebuild

[Purity Vendetta]

Nice job Yampug. When you say the exup bolts are a bit on the hard side is that when you try to drill them out? I'm going to strip my exup valve soon and I'm pretty sure the bolts are going to shear off. We've got a pretty substantial pillar drill so hopefully they won't be too difficult to drill and re-tap.

[yampug]

i made the mistake of drilling a small hole in the centre then slowly going up in drill sizes i should have just gone straight to the 5mm bit. going up in mm increments i just ended up blunting the edge of the drill bit when i got to the 5mm bit. go for a slow speed good downwards pressure and it drills out with a nice continuous swarf coming out.

i'd recommend using a cutting oil spray i was surprised how much easier it made it -

learning curve for me i'm used to drilling wood not metal.

if i was doing it again i'd grind off the bolt heads remove the exup valve then grind the remaining bits of bolts flush with the exhaust, centre punch or drill with a small bit in the very centre then go straight for the 5mm bit then 6mm tap. worth getting an expensive drill bit i wouldn't attempt it with a cheapo black jobber bit. if it snaps off you're buggered.

quite satisfying to see the little exup servo doing it's job of centring the exup valve with the cables operating as they should.