Ben's '72 Interstate Rebuild

Let me do some checking on that. On my late 72 it seems like the washer with the tab(which I cut off) went on the inside of the timing side case. The reason to cut the tab off is to prevent it from breaking off and fouling the oil pump which means it would be on the inside of the case in order for that happen. You say you have another washer inside the case on the timing side? How much float does the cam have? Maybe someone with some recent experience can help out here. I'm going from memory when I built mine eight years ago. I will look at my Mick Hemmings DVD to see what he says. I wouldn't go any further until we get this straightened out. You might try posting just this question on the main forum which has a lot more viewers.

From the shop manual and Micks DVD
On 200000- 300000 engine there are two washers inside the crankcase, the chamfered steel washer which goes with the chamfer towards the gear on the cam and the bronze thrust washer with tab which goes between the chamfered washer and the inside of the timing side case. This is the one that can have the tab cut off. Mick mentions a second tabbed washer on the outside of the crankcase but it isn't mentioned in the shop manual and I don't recall installing it on my rebuild.

My 750 Combat engine sn 209xxx does indeed have two thrust washers - one in the crankcase and one in the timing chest. I have just finished rebuild of said engine and I cut the tabs off both.
Indeed the tab on the one in the crankcase poses more of a hazard if it fails but why chance it . The one in the timing chest could conceivably damage the cam chain and pinions if it came adrift. Mick advises removing the tab and it is also noted on the invoice from Andover to remove the tab.

Addendum - here is what a piece of piston ring does to the oil pump - this piece was 3/8 " long and managed to find its way from the sump to the pump and negotiating three 90 degree turns to boot !
The thrust washer tab being shorter would certainly make the same journey -

The piece left in the oilway at pump base -


and the damage to the scavenge gears in the pump - beside the offending piece in the photo another piece was forge welded between the teeth from the pressure of being squeezed between the gears .

You guys showing these pictures are going to be the cause of me having nightmares pertaining to my aging motor. I need peaceful sleep...…

I pulled the cylinders and the timing gear (again) and installed the second thrust washer in the timing chest:


I clipped off the tab and filed the washer. Many thanks for the tip since it didn’t show up in the Norton manual or parts schematics. I thought I was going crazy.

I didn’t have the heart to split the cases again to clip the tab on the inside thrust washer. Here’s hoping it stays whole.

The silver lining is that I’ve gotten pretty adept at removing and replacing the cylinders and timing assembly, having done it three times in as many days.

I plated the timing cover screws, then polished them and chased the threads with a whitworth die:






It was a lot work to keep some fairly chewed up screws, but they are MY original screws and I want to keep them. I think this idea of keeping the bike as original as possible is getting a little OCD.

Now to show what a hypocrite I am, I also fitted what I think is a CNW breather:


I bought it a few years ago and can’t remember who made it. I may refit the original breather in order to keep the bike looking original.

Next up finding tdc and timing the ignition. The heads are probably three weeks out at the machinist. Then on to the chassis...

Hi Ben - Can’t blame you for not wanting to split the cases again . Hopefully all will stay put - plenty of them do.
Your work looks very nice indeed and good for you on keeping all the original bits - I get it . I don’t have OCD - I have CDO . It’s the same thing only the letters are in alphabetical order AS THEY SHOULD BE !

Cheers - RT

Scout63, ref the reed valve breather topic... you’d have to be trying to impress some serious originality freaks if you insist on having original 1970s oil leaks...

Point well taken FE.

More thanks to Fast Eddie for giving me some big picture. I’m so busy assembling parts that I didn’t slow down to consider what a breather does and why the reed valve is important.

While waiting for the head to come back I started on the forks. Getting the top ring off is a #$&*@. The first one came off with heat and a strap wrench. The second one was not moving so I held the ring upside down in my vice (with duct tape on the jaws) heated the leg and turned the leg with a bar.


Everything inside looks fine save for one broken upper bushing. Everything is degreased and bagged. Sanding and polishing fork legs next while waiting for new bushings and small fork parts. I already have new tubes, springs, seals and dust covers waiting.

jbruney said:

You guys showing these pictures are going to be the cause of me having nightmares pertaining to my aging motor. I need peaceful sleep...…

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Take heart - Hopefully yours will keep on keeping on - but if it doesn’t you get to have this kind of fun !

Been through everything except the motor already. Hopefully it keeps going as it always has because it has been exceptionally reliable and a smooth performer. However I may donate a new oil pump to it soon for being such a good girl.

Sort of an important step today. I pulled the fish tote full of bagged parts from upstairs in the garage


Moving from the engine to the chassis. I bead blasted the triple trees and coated with a self etching primer.




Tomorrow after work hopefully I can finish paint the trees, clear the lift, set up the frame in a safe spot and assemble the swing arm/engine cradle.

How do you expect to put it back together by keeping parts organized? Where's the fun in that I ask when everything is right there to work with? I'd be lost for certain without it all being in a big pile.

Forgive me for mentioning it but you should not have any paint where the taper top of the fork sanctions go.

Roger that Bernhard. I’m sanding off areas where paint interferes. I test fit the swing arm/ engine cradle last night. I need new o rings that that part is on hold. Some random pics: top steering stem bearing photo is before the bearing is fully seated.

Paint stripper CAREFULLY applied with a small brush makes the job easier and you don’t risk changing sizes , diameters etc. as you may do when using mechanical means to remove paint.

Thank you Richard. I’ll try that. There is so much that I don’t know. Tubes and tires mounted. I installed the steering stem bearings without the spacer so I will have to drive one of them out again. This must be easier the second time around.

Scout63 said:

I installed the steering stem bearings without the spacer so I will have to drive one of them out again. This must be easier the second time around.

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Great job.
The spacer tube can be long so it does not hurt to seat the bottom bearing in the frame then draw the top bearing in until it contacts the spacer, easily done if you have original ISO flanges (They will contact both the inner and outer of the bearing and some full thread rod.
On my 850 swing arm there was 0.019" axial play with new bushes so I ended up machining a shim to move the D/S bushing inward.. fwiw.

Scout63 said:

I test fit the swing arm/ engine cradle last night. I need new o rings that that part is on hold.

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You've left out the dust caps as they go between the bush and the swingarm.