Bevel Gear Damage Question

[guzzijon]

I apologize in advance for any terms I'm getting wrong, feel free to correct me. I need you guys' help to assess the damage and tell me what needs to be done and what can be saved.

We took off the bevel gear cover on our newly acquired Monza project bike last night to take a peek and here is what we found:



If you look at the lower gear in the 1 o'clock position, it is missing a tooth. Then, if you look just to the right of that, it looks like it took out some little chunks of the cylinder head casting. Also, is that galling on the end of the camshaft damage related to whatever happened?

We found this place online that sells the bevel shaft with gear:

http://www.classicitalianbikes.com/inde ... 93&lang=EN

Is this all we will need? Or does the bevel shaft gear have to be paired with a camshaft gear as a matched set?

Is the cylinder head able to be saved with the chunks missing?

How about the galling on the end of the cam?

Does this make the engine a parts donor or should it be saved?

Thanks for any insight you guys can give this newby to Ducati singles.

[blaat!]

Looks like no big deal. The galling appears to be just the cam nut retaining washer. That washer has a cut anti rotation feature on the ID, and is folded over against one facet of the nut to prevent the nut from loosening. Those are readily available and cheap. When you get the head apart you will need to look at the cam to make sure nothing bad happened in there. I understand the gears are (ideally) matched sets, but this is second to proper shimming to achieve a good mesh upon reassembly. Bevel gears in good condition can be had used for a fair price on eBay if you wait it out. You can also ask around here under the parts for sale section. You may need to clean up the head if you plan to put a glass gear-gazer on though
-Jim

[guzzijon]

OK, thanks Jim!

[double diamond]

Jon,

You can use the cam gear if it hasn't been damaged by the bevel gear but inspect closely. You could ruin a good bevel gear if the cam gear is damaged. Verify the length of the bevel shaft before you buy one. 250 vs. 350, narrowcase vs. widecase shafts are different lengths. MW

[DewCatTea-Bob]

I apologize in advance for any terms I'm getting wrong, feel free to correct me. I need you guys' help to assess the damage and tell me what needs to be done and what can be saved.

We took off the bevel gear cover on our newly acquired Monza project bike last night to take a peek and here is what we found:

If you look at the lower gear in the 1 o'clock position, it is missing a tooth. Then, if you look just to the right of that, it looks like it took out some little chunks of the cylinder head casting. Also, is that galling on the end of the camshaft damage related to whatever happened?

We found this place online that sells the bevel shaft with gear:


Is this all we will need? Or does the bevel shaft gear have to be paired with a camshaft gear as a matched set?

Is the cylinder head able to be saved with the chunks missing?

How about the galling on the end of the cam?

Does this make the engine a parts donor or should it be saved?

Thanks for any insight you guys can give this newby to Ducati singles.

____ It would be useful to rotate the gears to get a better look at that busted-tooth...
Likely it's not COMPLETELY broken-away, and if so, then merely checking that all resulted particles are totally cleaned-out, ought be all that NEEDS to be done (considering the likely intended use of the motor).
The engine-work that such as a shop-dealer would insist needs to be done, is probably a legitimate matter of course if the motor is expected to be relied-upon for extended out of town trips, or of-course racing. _ Otherwise, so long as the bevel-gears are still meshing as originally aligned, then I'd expect no further expected-problems, (short term).
So unless you actually enjoy doing the (not really necessary) somewhat difficult engine-work, I'd suggest leaving it be until you find another complete cyl.head to replace the one you already have installed.


Dukaddy-DUKEs,
-Bob

[DewCatTea-Bob]

" You can use the cam gear if it hasn't been damaged by the bevel gear "

____ This is often fairly true but, as has been apparently heard from a good-source, it's best if the PAIR of bevel-gears are replaced as a 'matched-set' ! ...
The factory made reasonably sure that individually chosen bevel-gears from produced batches could indeed properly-mesh without more extreme need for running-in -(extended break-in period), which robs power.
__ In the past I've acquired lots of used engine-parts from those who had torn-down a number of Duke-single bevel-motors and allowed all their parts to get mixed-up,, and-so I later had to try matching things back-up and then found that it's possible to find bevel-gears which not only do-not mesh perfectly but also WON'T MESH AT ALL !


Dukaddy-DUKEs,
-Bob

[guzzijon]

Another question, would this thing actually run with the missing tooth? And I'm 99% sure the one tooth is completely gone.

[DewCatTea-Bob]

" would this thing actually run with the missing tooth? "

____ I don't think I've ever seen any engine run with any single WHOLE tooth ENTIRELY gone, but so long as the remaining neighboring teeth are engaging enough to keep the camshaft's timing from slipping,, then yes, the engine will be able to run. _ (However if either of those next-door teeth have been stressed, [as is likely when the missing-tooth got busted-off], then it wouldn't be too wise to trust that further teeth-damage won't later occur.)
To be sure that the correct bevel-timing has remained in-tact, turn-over the engine until the timing-mark/dots on both those bevel-gears are aligned,, if then you had felt compression (just before dot-alignment), and the ign.points look to have just then became separated,, then the cam & crank bevel-timing has remained set, (and ought continue-on staying so), so the engine may fire-up.


Hopeful-Cheers,
-Bob

[blaat!]

It seems risky to run it if the tooth is completely gone. I don't believe it would ever skip over the missing tooth, however it may begin wearing away at the adjacent teeth and create a lash spot. It may eventually bind and break more teeth.

Replacing the gears becomes a bigger project, but not unmanageable.

Remove the four head bolts and the head comes off as a unit with bevel tube and all.
Remove the bearing carrier cover opposite the cam gear - the one that says "250" on it. Remove the bolts, but don't pry it off - use a rod through the cam to tap it out from the far side.
There is a specialized tool to hold the cam while removing the cam gear nut, but I suspect most people use a home-made jobber like me. I can upload a picture of the one I made later if you like (I'm not at home now). The cam nut is a left hand thread I believe. An impact gun is most handy for removing this nut if you have access to one. Replace that lock washer before reassembly.
Remove the socket head bolts on either side of the bevel gear that hold the alloy tube on.
I think you can then gently tap the bevel gear (along with the alloy tube) downward removing that whole assembly. You will need to remove a cir-clip from the bevel shaft to remove the alloy tube, if I recall correctly.
Make sure you look for, and put any shim washers back in the same location and same exact order.
You are way down the rabbit hole now

Did I miss anything guys?

The bevel gear is permanently attached to the vertical shaft and gets replaced as a unit.

I think that is it. Reassemble in the reverse order.

Good luck!

[guzzijon]

Oh crap, I already started to pry on the cam cover a little. I got it out about 5mm then finally quit because something didn't seem right. I was pretty gentle with it and did not force anything. Hopefuly I did not mess something up.

Just to clarify, the motor is stuck. The plan is to pull the head, get the piston free, them tear the carefully all tje way down taking tons of pics.