Recommendations for 450 Desmo service intervals

[graeme]

All the tight spots I have found are on the closing cam just as it transitions from the round to the flat section.

[themoudie]

Aye Paul 1098,

I wouldn't disagree with Graeme and blethermaskite's advice, but will pop my info up for what it's worth! Somebody, may find it useful.

My old bird is a 1974 450 MKIII, so no closing cams. Oil change between 1,000 and 1,500 miles, using a proprietary 15W/50 synthetic oil and flushing out the sump before refilling, with an aerosol brake cleaner and magnet. Re-fill with 4.25 pints (2.4 litres), torque drain/filter plug to 20ft/lbs (27Nm).

Check the valve clearance every second oil change, hasn't moved since last rebuild 12,500 miles ago, 3½ years past. Set at 0.004" (0.10mm) on the inlet valve and 0.006" (0.15mm) on the exhaust valve at TDC.

Head bolt torque that I use is 25ft/lbs (34Nm) in a diagonal pattern, my head bolts are dot marked one to four (please yourself what order) and then nipped up to 28ft/lbs (38Nm). Checked after the first 20 miles and at the SAE40 running in oil dump, when cold at 28ft/lbs (38Nm). Re-check at the 100 miles, SAE40 running in oil dump, when cold at 28ft/lbs (38Nm). Checked at 500 mile oil change to 20W/50 multi-grade running in, no movement, then checked annually, no movement to date.

As for the

Every 6200 miles: Unscrew crankshaft plug and clean out debris.

Personally, I don't.

The problem is that to undo the crankshaft plug requires "force", sometimes BRUTE force depending on WHO has been before you and that includes the factory! Working, with the crankshaft in situ, never seemed a good idea to me, as picking lumps of hardened/compacted sludge/bits of metal out of the trap, whilst not dropping it into the sump is always going to be problematic and if you dislodge a bit and don't remove it, where will it lodge and potentially block an oilway?

Keep the oil supply clean, don't use cotton waste/rags near the filler etc and using a multi-grade detergent oil, assuming that the engine has been newly rebuilt, should prevent a build up of sludge/debris in the centrifugal crankshaft trap. My engine has had it's 3rd rebuild since 1974 and over 90,000 miles and the sludge trap has only been cleaned at a rebuild. So, 20,000 miles, or every 5 years might be worth a looksee? Maybe Nigel Lacey et al would like to comment.

I hope that you get to enjoy the beasty and wear it out!

Good health, Bill

[Dodge]

Great advice!!
I sold my 450 Desmo 30 years ago and fully concur with these comments. Still running my 239 Mk3. Presumably a lot of the above advice is also relevant to all the WC singles.
Thank God the weather has started to improve.

[LaceyDucati]

Hi,

The collets (half rings) on the standard singles don't chew up as badly as the later bikes or twins as the heavy valve springs hold everything tight and avoid hammering. Running a Single without springs or with the twin assister springs for racing results in the half rings hammering out fairly quickly. MBP collets avoided some of this, but not sure they are still available any more.

An "upgrade" to a Valve spring head avoids any issues with no loss of power

As for Bill's thoughts on the crank sludge trap, I would agree. Best left alone, until overhaul after extended time and use. Don't build any crap in the engine and keep changing the oil...

Regards Nigel

[Ventodue]

<snip> ... but do the valves need doing every 310 miles or even 1240 miles and do the cylinder head bolts need tightening every 310 miles?

Ah! A case of, 'Choose your sources ...'

Because if you look at the late edition of the ITALIAN owner's handbook for the 250/350/450 Desmo/Mark 3/Scrambler, the answer is 'No' .

Instead:
Head nuts after the first 500km ONLY, and then not again (no surprise there)
Valve clearances every 1000KM ONLY.

Maint.jpg

[themoudie]

Apologies, if this is teaching your Grandmother how to suck eggs!

12,000 miles the steering head bearings and front forks WILL need a service if you haven't been there and done it at shorter intervals. That's ~3 years of running in my case and would apply to any widecase MKIII type machine.

8 of the 48 x 3⁄16 ball bearings were starting to gall and the steering was getting a wee bit sloppy, still plenty of grease in situ. Examined the head races, with a x5 lens and mine appeared OK. Installed new balls, using moly grease, put it all back together and you guessed, the bottom race is goosed! The balls have made small indentations in the races So, what to do?

The cups/cones were new 12,000miles ago, the bright chrome has flaked off and I suspect that the hardening of the races was questionable, to be polite about it. Maybe able to salvage with some hard chroming and re-grinding, but who/where? Buy another set of races of dubious manufacture, get a batch of quality items machined up and hardened, or go the taper bearing route? No stock at present! So, a call to see what the craic is, come the working week. POLITE SUGGESTIONS WELCOME!

At the same time the Marzocchi's were stripped and there was a bit of sludge in the bottom of the sliders, so all the internals will be flushed with paraffin, then brake cleaner, before re-assembly and filling with ATF. I have modified my forks, so the volume of fluid is not the Marzocchi manuals published voluime and I cannot remember what that is?

Whilst your at it, the front brake will need a check, clean and re-grease, or maybe new shoes/re-lining, if the linings are down to below 2mm thickness. If you've done the front brake you might as well do the rear as well and check the swinging arm bushes on top of that!

In conclusion, a FULL SERVICE!

I hope that you achieve these mileages and can then find the quality spares required for the rebuild.

Good health, Bill