Down pipes

[unfazed]

Does the chain need to be kept tightly tied, or just so it doesn't fall? The cams are aligned at tdc, so should be ok.

Thanks for detailed write up. Should drilling like that be successful or just if lucky? What about front cam guide, how do I remove that?

Just so it does not fall, but if it does it is not a huge problem as it can be picked out with a piece of bent stiff or Flexible Claw Pick Up Tool.

It has worked for me 9 out of 10 times and any time it did not there was exceptionally bad corrosion. The reason for leaving a few mm is get a grip with a vise grip to try unscrewing if the 4 mm bit does not twist it out. Most important thing is not to break the bit, so use good quality sharp ones bits. They may need to be ordered specially by your local engineering shop. The problem with using normal bits is that it is inclined to tighten the stud more.

Front cam guide does not need to be removed, but it just lifts out as it is only located in slots and the cam cover holds it in place