It looks a lot worse than it is, a wee bit of pitting at the top but nothing really worth worrying about.
I knew I would need it one day - that day took over 30 years to arrive but my Piston ring groove cleaning tool has at last earnt it's keep.
It's not perfect but it's definitely usable. I don't want to go too far on the polishing, I think this will be fine.
Having half stripped the engine and given the rest of the bike a good going over I have discovered a lot more about what I actually have. Some say I should have done that before I purchased it but you can only go so far and most sellers won't let you strip a bike down before you hand the cash over. They can be very sensitive about such things.
Firstly, the down side is that it's a 650, I was kind of hoping it had been upgraded to a 750, which would have added some oomph, these bikes are not very powerful by today's standards - in standard trim they put out 42 bhp, most 600 bikes that I usually work on have around 100-110, my GPZ1100 chopper produces just under 130. The difference is in weight, the chopper needs a crane to lift it, the drag bike I can lift with one hand.
The rest is pretty much good news, except for the water ingress in the right hand barrel which is about as welcome as Jimmy Saville in a boarding school. The pistons look nearly new, I think they are Powermax items, they are a thing of beauty. The left barrel - the one that hasn't had water in it - looks like it has been recently rebored, I suspect the engine did very little work since a complete rebuild, it has been over-bored by 20 thou, which takes the bores from 71mm as standard to 71.5mm. The weird thing is the pistons are plus 30 thou, all very odd, I didn't think you could or should put plus 20 thou rings on plus 30 thou pistons. It obviously worked though so that is what I am going with, a brand new set of Hepolite rings are on order, as are a pair of retainers to make installation a whole lot easier. I have already ordered a plus 20 barrel I found on ebay, that allows me to retain my high compression racing pistons and keep the bike to exactly the same spec as when it was last run.
The piston cleaned up really well and is absolutely usable, the rings will be replaced, even though they came out in one piece and don't look too bad at all. I heated up the piston to expand the ally slightly and that helped a lot. I got the chance then to use a tool I have had for 30 years but have never tried - a piston ring groove cleaning tool, it worked brilliantly and left me with perfectly clean grooves ready for new rings to go in to - result.
Now I have got rid of the ring of heavy corrosion near the top of the bore the engine spins over beautifully, the bottom end seems pretty much perfect. I will be having a proper look to make sure but I would be very surprised if I find anything nasty in there, I believe the piston rings stopped any water getting in to the crank area. I suspect very strongly that they will need changing though, the ones in the right hand piston must be proper nasty.
The Norton gearbox seems in first class order, all 4 gears select cleanly, it sounds really good when it's spun, the bearings feel perfect, so I am very happy with that. The frame all looks good, the front tyre needs replacing - no surprise there. The Avon racing slick looks hardly worn but seems very hard so that may be well past it's best too. Rubber doesn't like being aged so I always add new boots in to the equation. Both chains look usable, as do the sprockets. The front end looks fine, the brake works, not much to do there.
The magneto isn't producing a spark, which is a shame but not surprising. I don't normally have to deal with them as pretty much everything I work on is cdi ignition with coils - I know where I am with them. I am hoping it's just the points that are playing up, it all looks a bit corroded in there.
The carbs were pretty gummed up but some wd40 and half an hour did the trick, the slides now go up and down nicely, they look intact although I haven't looked in the float bowls yet.
It's been quite amusing seeing some of the chatter on the forums, it provoked quite a bit of interest when the guy I bought it from took it to Stickney auto jumble back in the summer. You got the usual comments from some folk that they would have snapped it up in a heart beat and others that thought it was worth about the same as 20 Rothmans. You gotta love the interweb.
like with all these things it is worth what somebody is willing to pay for it. I think that just getting it running will add significant value to it, I don't want to do a full resto on it because I think it looks super cool as it is, it has the patina that can't be recreated. I will put a new screen on it as the one it has is broken. I will keep the nosecone as is, I don't think I will repaint the frame, although I am still in 2 minds about that.
Anyway today I have to go fix some wiring on my mate's Ferarri Dino, the brakes need looking at too so that will keep me busy and out of my own workshop for the whole day.