Ducati Monster Forum

This is not a complete analysis of the perils of oil pump cross-fitment.
There are *at least* two oil pump configurations.
The "A" is a later configuration than the "B".
At this time, I DO NOT recommend mounting an "A" pump to an early motor.
More info will be posted as I get it further figured out.


Stopintime needed a set of primary gears, and I had a set.

There are different oil pump gears, so to attempt avoidance of that beartrap, I sent an oil pump with the matching gear.

The trans-atlantic shipment arrived intact, and I figured the whole deal was sorted.

His mechanic went to assemble the bits to his motor, and that's where it all went sideways.....  [bang]

So, to try and figure out where the train went off the rails, I gathered up a bunch of parts.

You like pictures, right?


(https://live.staticflickr.com/65535/47931502626_c87825a648_o.jpg) (https://flic.kr/p/2g2xtPG)

Here's two of the scoundrels, I've arbitrarily named them "A" and "B".
Both 33 teeth on the primary, so they're from small case 33:61 motors.

"A" has 25 teeth on the oil pump drive gear, matching "A" pump has 40 teeth, fairly large ones at that.
25:40 is a 0.625:1 reduction.

"B" has 30 teeth on the oil pump drive gear, matching "B" pump has 58 teeth, smaller ones.
30/58 is a 0.517:1 reduction.

So "B" turns ~83% as fast as "A".



(https://live.staticflickr.com/65535/47931491552_216eaf30bd_o.jpg) (https://flic.kr/p/2g2xqwL)

Here's a pic of the back sides, the dramatic tooth size difference is easily seen.


(https://live.staticflickr.com/65535/47931502511_30ea14432c_o.jpg) (https://flic.kr/p/2g2xtMH) (https://live.staticflickr.com/65535/47931497773_5291fe7c3d_o.jpg) (https://flic.kr/p/2g2xso2)

Here they are mounted up on a '99 M750 motor (10mm engine bolts, weak area at neutral switch, and 3 phase charging)

The "A" pump can be removed/mounted easily, even with the clutch basket/primary installed.

The "B" pump *cannot*.

I did both with the crank primary gear installed on that motor, YMMV.

The "B" pump is a serious beyotch, as with the larger gear it will just *barely* clear.
Pic below shows the position where it hangs up, and the orientation required to clear is shown within the green circle.
Requires patience and gentle wiggling to get it through the tight spot.
IMO, this could easily be a total no-go if the crank is shimmed a bit toward the alternator.

(https://live.staticflickr.com/65535/47931735178_70645225b2_o.jpg) (https://flic.kr/p/2g2yEXd)

Cool  8)

My cases are a little different than those in your picture. Not much, but enough to keep the pump from landing. The larger of the two oil galley 'towers' on the left is beefier on yours, but also machined(?) down 1-2 mm. Maybe that's all it takes? Plus a little shimming?

My motivation for buying these parts was:
 - get rid of a pinging noise (especially cold starts) Didn't help. (will double check tomorrow)
 
- get a new basket if the old was finished. The rivets on the old were loose. The rivets on the new were smacked in the head more than on the old. Firm.

 - including the primary drive gear because they are supposed to be mated/paired to avoid whining noises (noise AND clearance causes?) Must be several possible pairs in a bucket of random gears? If the bucket is large enough OR if I'm as lucky as ususal... (sorry Karma) Minor grinding noise when rolled on each other on a table top, but nothing once installed and fired up.

 - the oil pump gear was included because it might also need to be a pair with the backsside of the drive gear (?) Not sure the different oil pressure would have been a problem....

Yes, your cases are different.
I'll be fitting this stuff to a late model set of cases, need to put a crank in them first.

Loose rivets is terminal.

Yes, the intent was to keep a mated set of gears mated in the new motor.
That set was a mated set, but seems we've dodged a bullet and your crank gear is friendly to my basket gear.

And yes, intended to have oil pump gear to match.

If you're comparing cases... mine are from an SS (cast numbers close to the hor cylinder point to ~1998)