Rebuilding my 850 engine after it failed 2 years ago i discovered that both left hand side valve seats had dropped down and was smashed to bits by the piston and i also noticed the one of the cam lobes on the right hand side was badly worn down.Is it common for the valve seats to drop down? and were is the best place to buy a new cam knowing that it is not going to be soft and will a S2 cam give me a bit more go?.Thanks Paul
I would go to Andover Norton for the cam, they do chilled cast iron cams. I got a PW 3 cam on Norman White's recommendation gives me lot of grunt on my 850.
If you want top end you will need head work.
My 850 had dropped a valve seat and had had the wrong valve seat fitted to repair it. I had the head reworked by Norman White as well.
Welded up chambers and remachined, new valve seats, exhaust threads etc.
On stripping the head it was 2 seats that dropped and attached is a photo
Hi Chris,Who did your repair?Paul
Sorry Chris i misread your reply and i will give Norman a call,Thanks Paul
Paul...were those the original seats..do you know? I think lots were done unnecessarily (including my Dommie) when lead free petrol arrived because Norton twins already had hardened inserts.
Hi David,I don`t know if the seats were replaced as i bought the bike in 2007 and it was a Police bike and i was told that when it left the police the engine was rebuilt with new standard size cylinders,pistons and crank and i can confirm that now that i have the engine dismantled.Cheers Paul
Norman White Norton
Phone: 01264 773326
Hours: Closed · Opens tomorrow 9 AM
My bill came to £1280 but it included Head leak tested checking for cracks, heasd welded and remachined, new valve seats, new exhaust threads, valves, rockers shafls plates and screws, springsand reassembly. PW 3 cam and followers, pistons, barrel honed and repainted and three fins welded back on.
The work was carried out in 2011 Still working on bike but it is not too bad now.
Hi Chris.Nice looking bike and i will call Norman tomorrow.Thanks Paul
Ask either Norman White or Mick Hemmings what is the best cam to put in your engine and they will answer a PW3. They won't ask you what you want to do with your bike, or how you ride it. They won't tell you fitting a higher lift cam will affect reliability. They also won't tell you to get the best from a PW3 you need to do a load more work to the cylinder head. Big valves, porting, upping the compression etc.
I know for a fact that an engine overhauled by one of the above, fitted a PW3 cam to said engine without asking the owner first (who didn't even know what a PW3 cam was) and at the same time replaced the twin carbs with a single Mikuni. So at a stroke cancelling out any power gain from the new cam...
The aformentioned gentlemen had a batch of PW3 cams made and have been pushing them out to all and sundry to get back what they had invested.
Just fitting a PW3 to a standard engine will chop two or three horse power from the bottom end and put a couple on the top end and be more noisy to boot.
Getting hold of a standard cam is a little difficult now as AN are out of stock.
Getting your damaged cam welded and reground might be the better option.
Hi Peter,Thanks for your reply and thinking about it i am going to stick with a standard cam.Thanks Paul
Hi Paul, good idea to go for a standard cam, I don't think there is a great dèal to be gained by fitting a PW3. As has been said, at the moment AN seem to be out of stock and seemingly it will be a little while untill it is replenished. If you're going for a new standard cam ,just be very, very careful where you get it from. There is a supplier, where if there is a problem with the product, it will always be your fault for some reason or another, so tread carefully and don't purchase in haste.
Hi Ian,I have posted another post about my camshaft worries.Cheers Paul