Since finding the MB site I have been trying to gather as much info as possible to try and make my Cruzzer reliable with a modest increase on power. I have removed the m7 studs, fitted m8 inserts into the crankcase for m8 12.9 allen cap bolts and will replace the other head bolts with longer m6 12.9 allen cap bolts. I will also make some inox washers 2 & 3mm thick, max dia. I have worked on the inlet and exhaust ports to flow as much as possible, I could find no evidence of movement in the valve seats, but to be on the safe side I drilled and tapped two m4 retaining screws at a tangent to each seat 180 deg apart. I have had the head face machined 1mm (0.040") and will lap in on glass before fitting. I also lapped in the cylinder top face and was surprised how distorted it was. I will fit the original head gasket as I don't have easy access to spares as the Cruzzer is very rare in the UK and no spares are available and to order from the US or China would take weeks. I am now looking at the crankcase ventilation. The volume is too small for a single cylinder, so I have removed the std breather fitting on the case and am in process of making a bigger dia elbow into a vertical chamber to increase volume and I have ground two grooves at the base of the cylinder from the rear cavity on the crankcase to each cam follower gallery, also to aid breathing. I should know if it all works within the next few days. Dave.