450 SCR engine rebuild

[Wolf]

I've just started to strip/rebuild my 450 SCR 2nd series Motor. Main reason for the dismantling is that the layshaft/clutch has a lateral out of true by almost 1 mm, also I found on a regular bases small metal chips on the magnet of the oil dipper. After dismantling the engine, I can't imagine where these chips may have come from - strange.
To my discomfort, I've noticed that the cone the crankshaft is in a miserable state - this ruined also my nice new generator stator. Otherwise the crankshaft makes a healthy impression - what a pity.

My first question: are all bearings in the motor casing with the specification C3 ?

Many thanks

Wolf

[themoudie]

Aye Wolf,

I would suggest that the

small metal chips on the magnet of the oil dipper.

have come from the chattering between the alternator rotor and the taper on the crankshaft. My impression is that the gouging of both the internal and external tapers will not require metal spraying and re-machining and that a light "clean-up" on a lathe might suffice. BUT, I would have them inspected by a workshop with a working knowledge of Ducati single engine's working tolerances first.

In answer to your question:

are all bearings in the motor casing with the specification C3 ?

Yes, so far as I am aware. If you were to enter "C3 bearings" into the 'Search' window in the top right of the forum page, you should be able to find a thread covering this topic.

Good health, Bill

Um Wolf zu unterstützen, habe ich unten eine Google-Übersetzung in die deutsche Sprache gepostet:

Ja Wolf,

Ich würde vermuten, dass die [Zitat]kleinen Metallspäne am Magneten des Ölschöpfers[/Zitat] vom Rattern zwischen dem Generatorrotor und dem Konus an der Kurbelwelle stammen. Mein Eindruck ist, dass das Fugenhobeln sowohl des Innen- als auch des Außenkegels kein Metallspritzen und Nachbearbeiten erfordert und dass eine leichte „Reinigung“ auf einer Drehmaschine ausreichen könnte. ABER ich würde sie zuerst von einer Werkstatt prüfen lassen, die sich mit den Arbeitstoleranzen der Ducati-Einzelmotoren auskennt.

Als Antwort auf Ihre Frage: [Zitat]Sind alle Lager im Motorgehäuse mit der Spezifikation C3 versehen?
[/quote] Ja, soweit mir bekannt ist. Wenn Sie „C3-Lager“ in das Suchfenster oben rechts auf der Forumsseite eingeben, sollten Sie einen Thread zu diesem Thema finden.

Gute Gesundheit, Bill

[Duccout]

Hi Wolf,

Yes all of the bearings (with the exception of the upper and lower bevel shaft bearings) are C3.

I wonder if it would be a good idea to get a Woodruffe key fitted to the generator taper while you have the engine apart? I have heard of other owners doing this as the 450 seems to be very prone to having the flywheel chattering on the taper. Hopefully Nigel or Eldert will comment.

Cheers,

Colin

[Wolf]

Hi Bill, Colin

thanks for your input - I will use C3 bearings - ducativintagestore offers a set of bearings.

as for the crankshaft - I've acquired a left side half of a 450 crankshaft for little money, I hope it will be in good order - if not I 'll go for alternative solutions. I appreciate the suggestion of using a woodruff key for the fly wheel.

as for my English: I'm sorry if it may be hard to understand. I write in English and translate it with an online translator back to German - when the translation makes sense to me I use it. I hope that my contents come through clear enough...


Kind regards

Wolf

[Duccout]

Hi Wolf,

I do not know if you will be able to use a different left-side flywheel, it may not match the right. See what Nigel says.


Cheers,

Colin

[Wolf]

...I'll hope for the best, the cost were as low as $ 10 (I've already forgot about the shipping cost from US to EU), it was advertised as a 450 part...

[A.I.M]

I'm interested in this topic, as I'm trying to help someone find 450-specific engine parts. I had noticed that both 350s and 450s have a 75mm stroke, but I don't know if that means the 350/450 crankshafts are interchangeable. Any thoughts? It seems like 350 parts tend to be a fraction of the cost of 450 parts.

Cheers,
Al

[themoudie]

Aye Wolf

I understood your posting, but wasn't sure if some of my colloquial English/Scots made sense!

My '74 450 MKIII widecase engine had a woodruff keyway machined into the left-hand crankshaft from new, quite why yours appears not to have had a woodruff key fitted is a mystery to me, but maybe not to others. Even with the woodruff key in place the torque of the 450 engine can cause either the key to shear, if the engine is lugged (ridden at low speed in a too hig a gear) or if the alternator rotor isn't torqued to sufficient torque. I know that when using a good taper, the two components joined by this method should provide sufficient grip not to part, but this is a Ducati 450 engine and I have had the rotor come loose twice; the first time involved having the crank taper metal sprayed and the taper re-machined, whilst the taper in the rotor was skimmed to clean it up. The second time the tab on the tab lock washer sheared and allowed the crank nut to slacken. Without changing gear, and keeping a constant throttle in 2nd gear, so as to avoid the characteristic "clunking", I managed to ride the 450 home a mile and get away with no damage to the taper, or the gears. A new tab lock washer and drive nut torqued up to 70 ft/lb or 95 Nm and all has been sweet since. DO NOT USE A CHEAP LOCKWASHER, DODGY NUT, to secure the rotor, or NUT LOCK/ STUD LOCK on the taper, as dismantling becomes a nightmare requiring heat and potential ruination of the rotor.

As for using another left-hand crank flywheel/shaft, I think that is a question for engineers, with specific Ducati single experience, so either Nigel or Eldert's comments would help. That is not to say that others on the forum are not qualified.

Good health, Bill

[Jon Pegler]

350 and 450 cranks may both have the same stroke, but the rods are a different length, so certainly not interchangeable.

[A.I.M]

Thanks, Jon, that makes sense.
Cheers,
Al