Engine cases

This was possibly one of the most demoralising parts of the whole build. The engine cases were showing their age - badly oxidised and battle scarred. I didn't want them polished to a mirror shine but I did want them to look presentable (remember, I'm not trying to win shows with this bike).

But they also had other issues. There were a couple of the fixing holes where they appeared to have been drilled out to take larger bolts and also the threaded sections on the left hand crankcase in particular were in a pretty bad way with many stripped threads etc. I'd already repaired the two threads in the chain tunnel by epoxying in a threaded "top hat" I made (see this page) but, of the eight remaining holes, I think I ended up repairing five of them, in a bid to try and make sure my bike doesn't live up to the "Royal Oilfield" nickname.

Looking at the enlarged holes first, I found an old pushrod that was not for this bike in the box of spares and it was just about the right diameter to fit in the enlarged hole. 

I drilled the holes out to suit and then cut a piece of the pushrod to a suitable length, before epoxying one into each hole. As an insurance policy, I drilled a small hole through the case and into the sidewall of each tube and epoxied in a short length of spoke wire to positively locate them. 

I carefully filed the inner faces flat and finished with emery on a flat plate to maintain a flat gasket surface.

So now turning to the crankase threads, I think there were 4 holes that I needed to helicoil. I can't pretend that I feel like I did an amazing job of that, but I think it is "good enough" - time will tell. What I did find out is that it is quite easy to remove a helicoil if you need to have a second go (e.g. I had one where I hadn't run the tap far enough down the hole). You just pick out the beginning of the "spiral" with something sharp, grip it with needle nosed pliers and pull!

One of the threads that I started working on turned out to be a threaded insert from a previous repair that had subsequently failed again! I ended up having to find a bolt of the correct larger diameter which I cut down to length; drilled and tapped the correct thread down the centre; ran a bolt down that hole to the end and then screwed it into place using loctite on the thread. Once it had set I could remove the bolt. I must say that I was pretty proud of that one!!

Now that everything was pretty sound "structurally", I gave it all a good going over with emery paper in successively finer grades, followed by a go with my polishing wheel in a hand drill and then Solvol metal polish. It took forever, as there were some pretty nasty scratches to grind out first, but again I'm fairly happy with the end result. The finishing touch was to paint in the RE logos using Humbrol model paint.

I also gave the valve cover the same treatment

Because of all of the work I'd done helicoiling etc, I was really agonising over the lengths of bolts to use to correctly hold the primary side cover tight and have a hope of getting a good oil seal. I'd bought a stainless steel allen bolt set. 

In the end I decided that I needed to assess each bolt individually and so measured the case thickness and depth of the screwed thread into the crankcase, then marked the calculated bolt length on an A4 print of a photo that I took. I mounted that onto a piece of card, so that I could keep the correct bolt in the correct location when I need to remove the cover in future. 

Each bolt was then cut roughly to length and brought down to the calculated length using a belt sander.

This whole area seemed to take weeks but I was reasonably comfortable that I've got a nice tight seal on that cover - again, time will tell.

The right side cover was a piece of cake by comparison, but of course that doesn't need to retain oil in the same way. With everything fixed in place, she is starting to look a picture now.