So in the process of putting my newly serviced H89 'head back on, I snap the front bolt of the rocker shaft at 19nm (Aren't they supposed to be tightened to 25nm?), and decided now would be a good time to take a look at my carbs. They are covered in muck and white stains.

I'm pretty careful about cleaning them as I've heard they need to be handled extremely carefully. I have no fund to spend on them at this moment, but this is the ideal time for maintenance on them.

Any suggestions or advice on this matter would go a long way for me as this is my first pair of Hitachis. Where do I start? How full do I fill them up? Is sewing machine oil correct? My father suggested cleaning the inside with penetraing oil and not fuel, is this correct? Can I clean the outside with fuel?

I appreciate any advice in advance!