75 Mark III refurb/mod project

grandpaul · Oct 22, 2009

Next disappointment - the dreaded "D" spec connecting rods. No big deal, they were beat all to heck anyway.

Last disappointment (for today) - cam followers were trashed by the pitted cams –

GRM 450 · Oct 22, 2009

Thanks for the pics GP,
Another "quality" cam,
And rods,
Interested to see what's floating around in the dark, oily innards?

grandpaul · Oct 22, 2009

Stay tuned to this thread...

RennieK · Oct 23, 2009

Great pics, a great post and yet another excellent thread GP! I know it's not so convenient stopping to take photos when you're right into things. Do you have a computer in your shop?

Oh man, things sure took a turn for the worse. Just goes to show, we don't always know what we think we know about our engines. I had to go back to page 1 and here's a quote - "3. It will not be a total engine overhaul, just a beefed up top end job (bottom end is in great shape)"

It's a good thing you dug into it when you did. I wonder what shape the bearings are in.

Thanks a lot GP your extra efforts are much appreciated!

grandpaul · Oct 23, 2009

Righty-O, the bottom end was not in the plan. it is now! Since the top end was coming off, a cursory visual inspection of the bottom end was anticipated anyway, not like I was going to stuff it with rags and disregard it altogether.

My garage/shop/office is all one building, but it's like a maze. My camera is rather shopworn and greasy, but does the job under stress.

...just doing what I love to do...

Cookie · Oct 23, 2009

When I find stuff like that I have to tell myself better now than on the freeway a hundred miles from home.

grandpaul · Oct 23, 2009

Okay, now for the botom end. Inside cover appearance backs up my suspicion that the bike was run with dirty oil and/or hot for a significant amount of time; it's all toasty black and discolored inside all the oily surfaces, as are all the oiled parts-

Unsteady photo doesn't show well, but you can see excess gasket sealer and loose camchain, some oil pump gear wear (not too bad)-

Sludgy residue; check out the oil dribble, like molasses-

Cam tensioner foot is only very lightly worn-

grandpaul · Oct 23, 2009

Damage from the stray bit(s) was evident everywhere inside the crankcase-

AHA! Stuck to the magnetic drain plug was this-

A bit of forensics, and we have this-

grandpaul · Oct 23, 2009

A bit of simple deduction and a quick look in the other case half -

The sump strainer filter retaining circlip had somehow come loose, allowing the media retaining washer to escape. Apparently it was too large to be trapped by the magnet 'till it got folded up in the works.

Thankfully, the main journals are in good shape. Just a hint of wear on the left side, that will polish out-

Shells look like they did thier job, new ones will be straight replacements-

grandpaul · Oct 23, 2009

Sludge trap was actually quite clean, just a shmear of residue...

Removed the previously overhauled tranny (Old Britts) and stuck it in a nice box-

Stripped off all the rest; frame ready for monoshock modifications.

grandpaul · Oct 23, 2009

Valve pockets were really pasted with burnt oil residue, and the stem / guide gap is sloppy. Time for new valves & guides.

Step one in the mockup phase - fit up the ZX9 forks

grandpaul · Nov 4, 2009

First box from Dreer arrived, here's the VR880 front hub-

JE 880 pistons & rings-

grandpaul · Nov 7, 2009

More new stuff!

Kibblewhite racing vale spring kit with collets & retainers, all new crankshaft fastener hardware-

Rowe valves, "Superblend" main bearings, new camchain, Timing side cam bush-

Drive side cam bush, intake & exhaust valves, con rod bearing shells-

grandpaul · Nov 10, 2009

Kinda kicking myself for not getting good "before" shots of the crankcases, both inside and out. I did get one close-up of the outsides after preliminary scrubbing, they had some sort of green boogers on 'em that was a real mother-in-law to get off-

The results (ironically, the shadows in this shot have a greenish hue)-

Custom fit yoke stem, turned to accept Norton head bearings, steering stops welded on (I need to go back and do this to my 880)-

Head & cylinders are at the machine shop along with pistons, rings, valves & spring kit, just waiting on the intake guide seals.

grandpaul · Nov 11, 2009

Nifty new con rods, NON- "D" spec! All new fastener hardware, too.

I can assemble the crank today, but the Megacycle cam is still on it's way, so the cases won't go together just yet.

grandpaul · Nov 12, 2009

Crankshaft all nipped up with new fasteners torqued down to the max-

grandpaul · Nov 13, 2009

Got the jugs back, really nicly cut & crosshatched, very clean.

New gaskets & steering bearings -

Cookie · Nov 13, 2009

We should see some action on this soon with all those bits coming in. I'm hoping I just get a couple parts before the rain.

grandpaul · Nov 13, 2009

Just waiting on the cam & radiused followers from Megacycle, and the bottom end will go back together.

Meanwhile, I'm about to start on the Mark 3-1/2 monoshock swingarm for it...

nortonspeed · Nov 13, 2009

Next disappointment - the dreaded "D" spec connecting rods. No big deal, they were beat all to heck anyway.

The story of the inferior D-type rods sings around for some years now. Recently there was an publication in NOC magazine 'Roadholder' by John Dunn (technical advice team) telling us he covered over 80.000 mls with his D-type rods and advising us not to hurry changing these rods. Have you experienced yourself fracture of these rods? Or anybody else?
GP keep up the fine work!

75 Mark III refurb/mod project

nortonspeed

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