|Pete Murphy renews a pair of carburetors, part I|
|Here are the
carbs as removed from the bike - PZ24:
This is what the castings looked like after boiling in detergent (clothes washing powder) for an hour or so:
I boiled them up gently and let them cool down slowly to avoid any distortion. Here's the same carb after a once over with fine wire wool next to all the small components after a couple of days in vinegar (the casting is a bit splattered with vinegar in the pic - its cleaner than it looks here). The rebuild kit is in the front but is largely inferior to the original parts which I've decided to re use in the main. The new jet is good though (I'm gonna need a few) and new copper floats have been ordered.
I couldn't get a great pic of this but hopefully you can just see the concave shape of the manifold compared with the straight edge. Not ideal for an air-tight joint. I think lapping is just good practice before refitting with a new gasket
Tools required: piece of thickish glass, permanent marker, wet n dry paper - I used 400 grit, glass of water. Colour in the surface to be lapped:
Place long strip of wet n dry paper on the glass sheet and poor some water on it. Getting started is the hardest as it'll wobble a bit, so I start with long strokes:
The high point is obvious after a couple of strokes:
Keep rubbing, it gets easier and starts to feel more solid on the paper as you go
I'm using quarter sheets and shorter strokes at this point. Doesn't hurt to re colour as you work - just to be sure:
Keep rubbing until flat:
Ready to fit after about a sheet and half of paper and 35 minutes later.