Race Clutch and piston.

[Ian B]

In the parts collection for the projects I've acquired is this clutch basket and matching straight cut gear, they look to have no wear and may never have been fitted. The newspaper it was wrapped in is 17 years old and I believe that this is when the bikes restoration was started (and then abandoned!) Anyone know was this type of clutch available from Ducati themselves or was it an after-market part and if so what make?

_MG_0009.jpg

The piston on the 'race' engine I have has the number 4-65076/3 marked on the crown. It is a high dome piston and has 2 cut-outs for the spark plugs in a dual plug head. Whether these cut-outs were standard or have been added afterwards I don't know. I've searched the net for this number and have not come up with anything. Does anyone knows the make?
The clutch is surplus to my requirements so if anyone needs one I'd like to trade for a Yellow Desmo style, or nice cafe racer seat.

[DewCatTea-Bob]

[quote= Ian B ...
" Anyone know was this type of clutch available from Ducati themselves or was it an after-market part and if so what make? "

____ I assume it's a Ducati-factory straight-cut racing-set intended for a F1-racer (which was available by special-order).
How many teeth are on each of those primary-gears ?



" The clutch is surplus to my requirements so if anyone needs one I'd like to trade "

____ Such a NOS factory-matched primary-set ought-to be pretty/quite-valuable ! _ Although certainly not-sure exactly how much, I wouldn't be surprised to see the pair fetch up near 500% that of a NOS std.primary-set*,
(* of-which I think is worth at-least 100-$).



" The piston on the 'race' engine I have has
a high dome piston and has 2 cut-outs for the spark plugs in a dual plug head. Whether these cut-outs were standard or have been added afterwards I don't know.
Does anyone knows the make? "

____ Well, how-about a picture of that as well ?


Duke-Cheers,
-Bob

[Ian B]

Many thanks for getting back to me Bob.

____ I believe it's a Ducati-factory set intended for a F1-racer (which was available by special-order).
How many teeth are on each of those primary-gears ?

26/64

____ Well, how-about a picture of that as well ?

Sorry about the photo, it's the only one I have of it for now.

_MG_8523.jpg

[Eldert]

the straight cut primary gears look like aftermarked to me .
this is what i found inside 250 M1S nr 23 :





Eldert

[DewCatTea-Bob]

[quote= Ian B ...
" 26/64 "

____ Then the resulting gear-ratio of 2.46:1 is too low to be intended for any race-motor other than the 250F1.



" Sorry about the photo, "

____ I've never had a piston exactly like that.
I've heard-tale of plug-notches on the sides of the crown described like that before but, didn't realize they'd be quite so deep. _ I'm wondering how thick the crown-alloy is left (between the bottom of the notches and the underside of the piston-crown) !?
Whether those plug-tip clearance-notches were done by the factory or a fairly talented previous-owner, is difficult to be sure of,, however a clue might be as to whether or not the piston states 'BORGO' on it. ... If it includes a 'BORGO' stamping, then it could've been non-factory modified,, however if there's no sign of any manufacturer-name included, then I'd more suspect that the notches were factory-done.


Dukaddy-DUKEs,
-Bob

[DewCatTea-Bob]

[quote= Eldert ...
" the straight cut primary gears look like aftermarked to me . "

____ Well Eldert, you certainly know more about these primary-sets than I do ! _ But what aftermarket-maker in the-world would've ever bothered to independently produce such primary-gear sets for Ducati's 250-motors ??



" this is what i found inside 250 M1S nr 23 : "

____ So how many teeth are on each of the gears of your straight-cut primary-set ?



____ Thanks for the posted-pix of your extremely rare M.1.S motor,
it's a certain privilege to have seen !


Enlightened-Cheers,
-Bob

[Eldert]

Hi Bob

this engine is not mine . did not count the teeth on the clutch . just had enough time to make a couple pictures before it got shipped to Japan .

Eldert

[Ian B]

Eldert and Bob, it certainly looks similar but is not the same size. The primary must be bigger and clutch basket smaller as you can see where the gear pattern is cut into the basket ears. One thing I'm loving about Ducati single ownership is the amount of experience out there that people such as yourselves are willing to share!

[LaceyDucati]

The Primaries look like Wygaty primaries made in the UK in the 80's. They also made gear sets, which were continued by Graham Dyson of Nova as from the late 80's. There are quite a few sets of these about in race engines in the UK and were available in 250 and 350 ratio's. I have seen factory straight cuts, but they didn't look like that.

Piston looks home modded to me, seen loads like that, the slots are just one of those ideas people try. They are usually original Borgo's with the top ring land reduced to create a higher dome/compression ratio. The pockets have had the edges radiused, which is quite a normal race mod, I would have to see the underneath of the piston to identify it. I would put money on that piston not being factory supplied as is.

Best Wishes Nigel

[Ian B]

The Primaries look like Wygaty primaries made in the UK in the 80's.

Piston looks home modded to me, seen loads like that, the slots are just one of those ideas people try. I would put money on that piston not being factory supplied as is.

Best Wishes Nigel

Many thanks for that Nigel, the engine is built up now so the piston will remain a mystery for now!