850MkIIa rebuild underway

All i have to say is that I ran a Pontiac oil filter, oil in the frame, and a big oil tank. The operating pressue changed only in the fact that during a high speed run the pressure did not go down while hot as it did before. It ran cross country like that and then for years in SF. I imagine my pressure relief valve did not have to open as much since it was pushing more oil furthur.

So....I'm as guilty as anyone!



Oh yes - the Commando

I got the frame supported on an old MX paddock stand which worked well and enabled me to start in the middle and work outwards.
Once I'd got the isolastics together and the swinging arm in place it was quite easy to get the gearbox cradle in and bolt the bottom end of the engine in place



The next job was to get the primary drive lined up, so I assembled everything without the cases attached; The RGM belt drive comes with some decent instructions, but some previous threads on the forum were also very useful references - especially with respect to belt tension (not tight is essential), and the alignment; i.e., gearbox mainshaft flex can cause the belt to ride off the clutch drum if not correctly aligned. To help with the setup I'd bought a double-sided adjuster:



The belt is retained by flanges on the crank pulley, and holds the belt towards the inner part of the clutch drum toothed area with plenty of 'run'out' area, as the drum is quite a bit wider than the belt.

I did have an issue when it came to final fit of the primary drive - I fitted the inner cover after getting the right spacer stack-up on the inner case pillar bolt, and fitted the clutch assembly complete with a clutch nut fitted with an oil seal, although this needed a little trimming to maintain clearance for the pressure plate.
The Norton clutch is so easy to put together I keep thinking I forgot something!



Once the clutch was together I checked for correct operation with a jury-rigged cluch lever, and it was remarkably light yet positive. I'd re-fitted the original bronze plates, and I'll see how they perform in a dry environment.
When it came to checking the rotation I was aware something wasn't right - there was a rather unpleasant metallic scraping sound, which I traced back to the clutch drum fouling the inside of the inner chaincase.

The culprit was the dome-headed securing bolts on the back of the clutch drum. There's a raised ring cast onto the inner case which needed grinding back te restore the clearance - I don't have a photo to hand right now, but I'll update later.

After this, the whole thing went back together in no time, and I'm looking forwards to seeing how it performs.

Meanwhile, back to the engine....

I'd got the barrels repaired and blasted, and after a coating of PJ1 they came up well.
One thing that suprised me was the weight of them - I'm now considering the alloy barrel option for the future, so I'd welcome anyone's comments on this.
I got new piston rings and circlips, and after cleaning everything up it was time to refit the barrels.
My preferred method is to pre-fit the pistons to the barrels, and then offer everything up. It all went very well, but I did take my time with it.



Nearly there....



I gave the crankcase mouth a coat of Wellseal, and it all bolted down nicely. I did have a base gasket but elected to not use it.

At this point I realised that the cylinder head needed cleaning up and reassembling.
I'd had the exhaust collar threads repaired, and the rest of the head was in good shape.The only issue here was the original rocker spindles were badly worn, even though the valves and guides were in very good order.
It was all going great until I came to re-fitting the rockers. I don't know if anyone else has had this problem, but I couldn't get the new spindles to mate with the rockers - there was no clearance.
I checked the new spindles, and they were exactly the same diameter as the un-worn portion of the originals.
I pinned the problem down to the rockers having become distorted, so I had to hone them out with a Dremel to get them back into shape.
Has anyone else encountered this?

Finally, I will be removing the sump filter and I'll be getting the soldering iron out - once the bike's on it's own wheels

I'm out of photographs right now, so more later!

That's excellent work and a good steady hand with the photos. I ought to use a tripod, but that's too much hassle.

L.A.B. said:

Coco said:

but have you ever seen the trickle of oil that comes from the rocker feed of a Triumph?

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I believe the rigid rocker feed pipe acts as a restrictor, so is meant to be like that?

Coco said:

Running an automotive style filter like on a Commando will decrease the already small amount coming through to the rocker feed.

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I remember reading an article some years ago, in 'Nacelle', the magazine of the UK TOMCC where bench tests were carried out to determine if these filters actually caused any flow restriction. If I remember correctly the results were that the pump flow rates just weren't high enough for the filters to register any measurable restriction to the oil flow.

Coco said:

Maybe that MAP Triumph filter has a higher flow rate, and if it does I'll consider using it.

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The MAP filter I think, is either the 'Hide-de-Hi' filter (or a direct copy of it) that's been made in the UK by Bob Light for I'd guess around 20 years or so (I presume he still makes them?) which takes a standard BSA R3/Triumph Trident paper element oil filter, and I've never heard of any problems occurring with that particular filter design?
However for an OIF Triumph model, the frame plate filter (as shown by B+Bogus) is just as good as any other type in my opinion, plus it's hidden away with no extra pipework which could split or leak.

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I'm slapping in a Morgo plunger to increase oil flow, just in case. I'm still going to look into the MAP filter kit once the build commences. I think the restrictor is in the "T" fitting coming off the oil tank and not reliant on the small feed tube (?). I'm probably wrong as I don't have a stock bike and tank. Mine is a hard tail chop with custom oil tank ect. Kind of a mish mash of a 650 frame and a 750 motor.

If you omit the base gasket in favor of a coat of Wellseal, does that raise the compression ratio? and if so, is the increase at all material?

BrianK said:

If you omit the base gasket in favor of a coat of Wellseal, does that raise the compression ratio? and if so, is the increase at all material?

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I would guess it would be negligible.

Thanks Dave. That'd be my guess too (but a guess it is).

The INOA Tech Digest has a compression ratio chart. They list the difference between running with or without the base gasket on a 850 with an RH10 head, with 8.2, without 8.5. I don't know how accurate that is. They say the gasket is 0.018"

BrianK said:

If you omit the base gasket in favor of a coat of Wellseal, does that raise the compression ratio? and if so, is the increase at all material?

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I only left the gasket out because it isn't necessary; I believe they weren't fitted on the 850. I may be wrong, and I'll gladly stand to be corrected
I'm not looking for a compression ratio increase as such.

Anyway, here's that clutch basket with the button-head bolts:



This is the cylinder head with the new sleeves fitted.



Because the previous repair (plain sleeves welded in) had increased the bore size of the exhaust ports, I couldnt get a 'standard' repair done, so I got Burton Engineering near Fleetwood to manufacture threaded sleeves which were bonded in with high temperature threadlock (sorry - I forget the brand, but it wasn't Loctite). they've previously done a similar job on my Ducati, and it's been a good repair.
Incidentally, Burton Engineering used to do the Lancs Constabulary Commandos, and they used bronze exhaust nuts similar to the ones Norvil supply (now fitted on my bike). Apparently they used to just screw them in hand-tight and they never came loose.
I expect that some kind of glove device may have been used, though

Once I'd finished fighting with the rockers, I got it all back together and fitted with a flame-ring head gasket. I gave the areas around the pushrod tubes and the oil drain a light smear of Wellseal, based on the advice of the NOC Service Notes.



It was nice to be able to take a step back at this point to admire the handiwork so far...this has to be the best looking Brit engine after the Vincent!

Something I'd been looking forwards to for some time was fitting the Dave Taylor head steady, and even with an imperial sized frame, I found that the clamp was a good fit around the tube, but because the half-clamps aren't cut back it doesn't actually clamp up! So I need to remove some material from the mating faces to stop them...mating. That way they'll clamp up property :roll:
Nevertheless, I still like the design; it's by far the cheapest solution, and to my mind at least, adresses the issues as well as any.



I then remembered the words of warning regarding fitting the airbox, and how it's nigh on impossible to fit after the engine's in.
Maybe because it's a MkIIA, with bolt-on brackets, and not a MkIII - which has the brackets riveted on (i believe), it did go in after much wrestling. But it wasn't fun, and if there is a next time, the box will go in before the head goes on.



One issue I do have is the routing of the rocker feed pipe. I stayed with the OEM plastic pipe, and it has a grommet and a wire clip, and I haven't a clue where the clip attaches - any help would be gratefully received!

Onto the chassis next...

B+Bogus said:

I only left the gasket out because it isn't necessary; I believe they weren't fitted on the 850.

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Base gaskets were re-introduced on (or before?) the 850 MkIII models. http://www.nortonmotors.de/ANIL/Norton% ... 02&Part=25

B+Bogus said:

One issue I do have is the routing of the rocker feed pipe. I stayed with the OEM plastic pipe, and it has a grommet and a wire clip, and I haven't a clue where the clip attaches

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Thanks LAB - the usual level of service we've come to expect

If you have some photos of the wiring loom installation that would be the crowning glory!

I think I've got it sorted now, but before I clip it all up it would be useful to see where the stuff is supposed to go.
I still find it hard to believe that it was economicaly viable (the evidence suggests not...) to fit the police harness to everything!

B+Bogus said:

If you have some photos of the wiring loom installation that would be the crowning glory!

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Unfortunately, I don't, but others here may have?
In any case, the (my) MkIII harness differs in many ways to the earlier harnesses.

Now the engine is all documented it's time to move on to the major chassis items.

Note - this build thread doesn't necessarily follow the order I actually did stuff!

The swinging arm was fitted before the gearbox went in the frame, and as I was still waiting to get the shocks ordered I temporarily re-fitted the old ones just to keep things moving along.

I remember reading about some swinging arms developing a twist, and as mine is a later one with additional bracing I didn't believe it would be an issue, but I thought it better to check anyway...



I built the rear brake plate up with a new stainless torque stay as the old one had got mangled by the PO fitting it to the outside of the fork :roll:
I know I may be sounding like a bit of a fanboy, but the Stainless stuff from RGM has been very good quality, and I can highly recommended it (where's my fee?)



And here it is in position with a new Renolds chain. the whole thing feels a bit odd until the nut is tightened, and the stub axle bears up against the brake plate.



Since these photos were taken the nice new chainguard has required surgery to get the Ikon shocks to fit properly...fortunately it had already been mentioned on the forum, so I was prepared for it :wink:

Onto the front end...

The Lansdowne fork dampers arrived quicker than expected, and as has already been stated, I don't know how he can make them for this price...hurry up before he gets wise to it!
I also fitted progressive springs from RGM.



Note the different compression and rebound dampers



The only clue as to what's lurking inside!



I also put new bushes in....I thought about using the longer top bushes which are now available, but decided against it. Once I'd assembled the legs I checked the forks individually without the top nuts fitted (i.e., dampers inactive), and they aren't totally smooth. They're OK around the top-end, i.e., extended, but they start to offer some resistance towards full compression. I'm guessing that the lower bushes/sliders are the issue, and that it's just a bedding in thing; the effort required to get them sliding really isn't much. If it was a race bike I'd be a little bit concerned, but I'm pretty confident they'll bed in OK.
If they're still tight after the bike's run-in then I'll do something about it (what, I don't know!). I'm sure the Preston roads will sort them out



The original head bearings were in fine order, and apart from some pratting around with bundles of O rings and headlamp brackets, it gave me no major headaches, and the front end was on and ready for the re-painted clock holders.
Note the shiny new VIN Plate on the headstock. It just wouldn't be 'proper' without it...



Finally, I rebuilt the original caliper with stainless accessories. I have it on very good authority that the EMGO pads will be just fine



More soon (when I find the camera)

B+Bogus said:

It was nice to be able to take a step back at this point to admire the handiwork so far...this has to be the best looking Brit engine after the Vincent!

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I'm with you there.

Great stuff Andy, keep it coming. Interesting about the bronze exhaust nuts. My man told me the other day that there's no difference between them and the chromed steel ones but I'm going the bronze route myself when he gets some into stock.

I you wish to change the OEM cylinder to a aluminium one, the one from Steve Maney is the good choice, 9000 kms already without issues
Yves

Fullauto said:

Great stuff Andy, keep it coming. Interesting about the bronze exhaust nuts. My man told me the other day that there's no difference between them and the chromed steel ones but I'm going the bronze route myself when he gets some into stock.

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I'd say you're doing the right thing - my Ducatis have bronze exhaust nuts and they don't come loose unless there's a reason. The thermal expansion rate of bronze is quite close to that of alumnium; steel is a different story...

yvesnorton said:

I you wish to change the OEM cylinder to a aluminium one, the one from Steve Maney is the good choice, 9000 kms already without issues
Yves

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Yves, I'm pleased to hear you're getting good service from Steve's barrels - what capacity & compression ratio did you go for?

Entre nous, I'm waiting for my birthday before I talk to my wife about the next 'essential upgrade'
It also helps that he's about an hour's ride away from here.

I'm wondering what the story is regarding the significant differences between the left and right fork internals?

grandpaul said:

I'm wondering what the story is regarding the significant differences between the left and right fork internals?

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In simple terms the Left hand looks after compression and the Right hand does the rebound damping; similar to modern practice; for more details:
lansdowne-fork-damper-kit-t4683.html?hilit=lansdowne

grandpaul said:

I'm wondering what the story is regarding the significant differences between the left and right fork internals?

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Overheated brake cooking the fork oil?

Not enough fork oil, causing it to overheat?

Water or other contaminates?

Hi b+bogus
I to have a mk2a here in newzealand engine #308408 it was imported from usa in the early 1990's