CB500 Shim Replacements
A couple of weeks ago I finally plucked up the courage to open my engine and measure the valve clearances. With new shims in my grubby hands it was time to set about swapping them.
Well you didn't understand did you Sush?
As I sat preparing to fit the new shims I could hear the old adage measure twice, cut once in my head. Something didn't feel quite right so I decided to make a cuppa and double check my measurements.
It turns out I had misunderstood the manual and took it's example of shim calculations as the optimum shim height. Realising this I redid the calculations and got in touch with Rob Carver at SF Parts to explain my error and organise new shims and a refund on the ones I bought. 2 days on and the right shims arrived so I could get cracking.
Let's do this properly - again
It was actually an enjoyable job to do weirdly. Maybe I built it up in my head but I took my time, using a magnetic tool to pull each follower off revealing the old shim. Each part was laid out on some cardboard with a drawing of the head on to ensure it went back the right way.
A 50/50 mix of grease and engine oil was used on the shims, followers and cam lobes and in the time it takes to neck a mug of tea I was ready to pop the cam shafts back.
Tippex and some blind luck
Putting the camshafts back involves getting the chain fitted at the bottom of the engine and then keeping tension on the chain as the camshaft goes back in the same position it was taken out. I used a little tippex to note where the chain and sprockets were just to give me a fighting chance of getting it back exactly as it was.
I wouldn't know until I tried to fire the engine - but if the timing was off it could cause real problems in the engine.
The simple pleasure of a torque wrench
It shouldn't be a new thing to me but I am ashamed to say until playing with the engine I have always tightened things with a pure guess at the torque they should be under. A christmas present treat to myself meant I now have a lightweight torque wrench for more delicate things with a 2-24NM range.
The click when you reach the correct torque is one of the most satisfying things ever!
Making sure I was very even and tightening in a criss cross pattern the cam holders were back on and I took the chance to replace the gasket on the valve cover whilst I was at it.
BIG moment, the engine is now done - just got to hope I can put the bike back together and get it to fire again!!
Next time... how on earth do I get the engine back into the frame??