750 SFC oil pumps etc

julian

julian

Hero member
Location
Belgium
Hi,
We all know about the SFC oil pump being larger etc and the 10mm pump available from Laverda Paradies in Germany.
However, Piet mentioned 10mm gears from the 3C? or jota? fitting with a bit of machining?
Tell us more Piet as I need to do something on the 1000 conversion and don't like the look of the big billet block from LavParadise.
Are 10mm gears available? and do we just need to machine the housing deeper to accept the gears or is there more to it?

I was going to PM but it's obvious that others could benefit from this info too.

Regards,
Julian
 
Hi Julian - On the 500 that we did a 600 conversion about 30 years ago - has same type pump set up as the 750's and triples we made a plate that was dowelled accurately onto the pump to increase its width and put in thicker gears. Still working fine today! - Regards - Phil
 
Hi Phil,
I haven't looked hard yet but I seem to remember there not being much room to add stuff under the gear, that's why I asked if people just "simply" machined the gears deeper into the upper crank case.


Regards,
Julian
 
Quite easy, Julian.

At the time, all I had was stock 6mm and SFC 9mm gears and housings.  Both gears are dimensionally the same, only difference is the width.  Reckoned if I could somehow get them to ride piggy back, it would end with a nice 15mm pump.

First a bit of space was needed as the outer face of the pump still needs to fit under the primary cover.  The upper crankcase was milled back at the oil pump surface by 6mm after pressing the bronze bush inwards a further 6mm.  An old 6mm pump housing was top-chopped to aquire a surround for the gears and placed beneath the SFC housing.  The 2 sets of gears were just placed diagonally across each other inside so that the drive peg engages with one 9mm gear, this in turn drives the 6mm gear and part of the 9mm gear opposite and the 9mm gear drives the 6mm gear on the drive side.  The pump shaft remained in stock form, the idler axle is long enough to cope, all that is needed is 4 longer M5 fixing screws for the pump housing.

Did the mod twice, first on my GTL which has covered 60000 problem-free kms since.  The other was done on a '74 SFC along with other serious top-end oiling mods (end-feed to hollow camshaft, cross-drilled to supply the rockers, spin-on oil filter).  Experienced serious rocker compartment flooding at first, but modified return tubes pressed into the head cured that.  This engine has also done many 1000s of km, both on the road as well as on track days.  It took part in at least 5 Bikers Classics events nad has not been opened since the pump mod was finalised.  The engine showed 85hp/80Nm on the Moto Witt dyno, still in stock 750 configuration with stock carbs and SFC 2-1 exhaust, but hardly suffering once the 2-2 road exhaust was fitted!

piet
 
Right then Piet,
Can I have some of them there 9mm gears please?  What? Where? When?  :D
Sound good to me! knew I asked the right question in the right place  ;)

Julian
 
I've never looked at the oil pump in my 1976 3CL/Jota. There's no mention of it being upgraded in the maintenance notes that the PO gave me with the bike so I guess it's original. I've occasionally wondered whether an upgrade to 10mm would be beneficial. However, the bike has done nearly 100,000 km without any problems so it's obviously getting enough oil.

I do like the idea of more oil flow, but that's just an intuitive feel rather than any sensible engineering reason. Is there any evidence or history of failure to suggest that the early pump on triple engines (6mm?) is inadequate? I know that the factory went to 10mm on 120 engines, but they also added an extra oil feed that squirts oil at the primary chain, which may have been the reason for the bigger pump.

Cheers,
Cam
 
Cam,

The original triple pump is 7mm wide.  It was upgraded for the 1200 and Jota models to 8mm.  The RGS got a complete new design (tooth form, tooth count and gear diameter) which raised flow by a whopping 54% over the 8mm type. 

There's a lot of bikes out there coping well with the stock pumps, there's also a lot of bikes out there on the verge of self-destruction... Laverda must have known something!

I upgraded as the new pumps became avaiable, never noticed any great improvement by the seat of the pants, but it does give peace of mind. :D

piet
 
Just resurrecting an old thread rather than starting a new one.

I just measured the oil pump in my 1976 Jota and it's the original 7mm wide gears.

What's the recommended upgrade for these old bangers? I recall reading somewhere that 10mm aftermarket pumps are poor quality or problem to fit. It may have been gears jamming or something like that. I can't remember the details. If there is a quality issue, is there a recommended supplier of good pumps?

Cam
 
Hi Cam -  Best pump to fit is the RG series type - wider cogs and better teeth pattern - have got one used available ATM if you want details give me a Pm - regards - phil
 
Hi, Cam.
The trouble I experienced with both twin and triples cnc-oil pumps
was that the gears were a little bit too wide and had to be sanded
down before mounting.

Ernesto
 
Tidying up the office has one huge advantage, you find things that have gone missing for quite some time... :o

I finally found my oil pump data sheets. :D

750 pumps @ 6000rpm engine speed (3000 pump rpm)
stock 6mm/15T/22mm dia. gears,                                  3.61 litres/minute
SFC 9mm/15T/22mm dia. gears,                                    5.42 litres/minute
Aftermarket 10mm/15T/22mm dia. gears,                      6.02 litres/minute
My own concoction with 15mm/15T/22mm dia. gears,      9.04 litres/minute

Triple pumps @8000rpm engine speed (5400 pump rpm)
early triples 7mm/16T/23mm dia. gears,                        7.84 litres/minute
Jota/1200 9mm/16T/23mm dia. gears,                            10.09 litres/minute
Aftermarket 10mm/15T/22mm dia. gears,                      10.84 litres/minute
RGS 10mm/12T/23.5mm dia. gears,                              15.61 Litres/minute

4-valve pumps @8000rpm engine speed (3285 pump rpm)
stock 500 7mm/16T/23mm dia. gears,                            4.77 litres/minute
500 Formula 9mm/16T/23mm dia. gears,                        6.13 litres/minute
OR600 10mm/15T/22mm dia. gears,                              6.59 litres/minute

Conclusion;

Unless the stock early 7mm pump is fitted, there isn't such a great advantage in fitting the 10mm pump to a triple, unless of course the prior pump was knackered.  The biggest improvement to be achieved is by fitting a 120? RGS-type pump.

Upgrading the stock 750 and 500 pump is a good thing, no matter from which angle it is viewed. :D

Calculations do not take wear or possible defects, or even possible cavitation into acount, just the theoretical volumes!

piet

 
Thanks Piet,

do you also know the data from Zane engines?
It seems you only have drill one hole to fit these into a 500 engine.


Hans
 
HansL said:
Thanks Piet,

do you also know the data from Zane engines?
It seems you only have drill one hole to fit these into a 500 engine.


Hans
Click to expand...

No, and I don't really intend to delve into that quagmire... :D

piet
 
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