M900 exhaust Flange

[crust]

Don't forget, the rear cylinder one has a cut out to clear the head.



https://i.ebayimg.com/images/g/Ep0AA...o~/s-l1600.jpg

[slob]

Originally Posted by crust

Don't forget, the rear cylinder one has a cut out to clear the head.



https://i.ebayimg.com/images/g/Ep0AA...o~/s-l1600.jpg

Good spot Mr. Crust, do you have a measurement? I can do a second version... of course that'll push the machining cost up for anyone who gets them made.

[Nasher]

Originally Posted by crust

Don't forget, the rear cylinder one has a cut out to clear the head.



https://i.ebayimg.com/images/g/Ep0AA...o~/s-l1600.jpg

I didn't find that on my Carbie 900, the one I posted the image of fitted both cylinders.





Nasher.

[Mr Gazza]

Both my clamps have that chamfer, but it does not appear to have any purpose.. It's certainly not for clearance of anything on my M900ie model.
Maybe just to make the front one a bit more aerodynamic?

[Darkness]

Stein Dinse list the flange part number as fitting:


Ducati
Ducati 750 Paso `84-`92 , BJ 1984 - 1992
Ducati 750 Sport
Ducati 750 SS `91
Ducati 750 SS `92
Ducati 750 SS i.e.
Ducati 750 F1/Laguna Seca
Ducati 900 SS `90
Ducati 900 SS `92
Ducati 900 SS F.E. `98
Ducati 900 SS inj. `99
Ducati 900 SS/SL `94-`97
Ducati 906 Paso `88
Ducati 907 I.E. `92
Ducati Monster 600 `94
Ducati Monster 600 `98
Ducati Monster 600 `98 Dark
Ducati Monster 600 `00
Ducati Monster 750 `00
Ducati Monster 900 `93
Ducati Monster 900 `94
Ducati Monster 900 `98
Ducati Monster 900 i.e. `00
Ducati ST 2 `97

Some of which have the rear cylinder head “reversed” with the exhaust port at the front. That must make the exhaust radius pretty tight from the head to require the chamfer.

[Mr Gazza]

I think the only one with a reversed head on that list is the 750 F1. All the exhausts I looked at on google images seem to have a good straight length coming out of the port, so I don't think that's the reason for the chamfer.
The clamps on my 750 seem to be a slightly different design. (no idea if they would interchange with 900?) They have no chamfer on either clamp and don't interfere with anything. However, on the smaller engine the clamp would get very close to the crankcase when at the end of the studs and be tight to get off to release the collets. I can only assume that it would be tighter still on the 600 engine and a chamfer might make all the difference, but I have my doubts as to 900 and 600 clamps being the same animal?

I think this chamfer might be a Red Herring?

[slob]

If someone can measure and let me know how much needs milling off that side to match the stock part I'll upload a file so both with and without are available.

[utopia]

I fitted a Sil-Moto big bore exhaust from an M900 to my yr2000 M750 a while back, which came with its own flanges.
The Sil-Moto flanges fitted my 750 motor (although the headers needed modifying) and so I was wondering if the std flanges were the same across the range. From the list that Darkness provided it would seem that this is commonly the case (though I suppose I would still hesitate to say for certain that it is always the case).
So I have (and can therefore measure) a pair of original flanges from my 750 amongst my stock of bits and pieces .. and these are very probably the same as 900 ones.

Using a decent pair of Mitutoyo dial calipers I have taken the following measurements to determine the stud hole spacing :-
Max distance across stud holes (ie between outside edges) = 2.790" = 70.866mm (ave of 4 readings).
Dia of stud holes = 0.351" = 8.951mm (ave of 8 readings)
Therefore, distance between stud hole centrelines = 61.951mm
I include all the above extraneous detail merely to indicate the accuracy of my measurements.
To all intents and purposes, the hole spacing is 62mm.
This tallies with Rob's measurement from the M1100.

I cross checked the dims from Nashers drawings and found that :-
Basic bore is confirmed at 48mm dia.
Basic bore increases to 54mm where the half rings fit (Nasher's drg states R26.5, ie 53mm)
Depth of this feature is confirmed at 2mm.
Max dia is 63mm (Nasher's drg states R33, ie 66mm dia) .. however the flange's outer profile is a little more "shaped" than Nasher's drg and the outer width in the area of the stud holes is approx 84mm. I can't confirm the 11mm radius in this area but its probably just down to a cosmetic blending.
Max thickness is confirmed at 16mm (I actually measured 15.875mm) BUT this is reduced around the stud holes to 14.75mm.

And, I imagine the flats on the flanges are to give clearance when used on the shorter stroke 750 and 600 motors.
These are tricky both to measure and to describe.
Using my engineer's angle gauge I reckon they are at an angle of 20deg to the axis of the exhaust port, ie 70deg to the flat face of the exhaust flanges
The "depth" of these flats leaves a land of minimum width 2mm (approx, by ruler) on the outside face of the flange and a land of min width approx 6mm on the outer dia of the flange.
There is also a small chamfer on the outer edge of the main bore. This is approx 2mm wide.

Obviously I have these flanges (and the associated half rings) to hand, so let me know if you need any other dimensions measuring.

Hope that all makes sense without pictures.

[slob]

Thorough as always Jeff! although I'm not 100% without a picture.
Since Nasher's collars look great and clearly fit, I've stuck with his measurements.
For the one with a flat, I've reduced it to 3mm where indicated but left it 'square' at the side rather than at 70deg.



Do you think it needs more material taking off?

A 'nearest mm' measurement with a ruler, to the flat from the other side would have done for me

[Mr Gazza]

'Scuse the Sugar beet in the fins, I ride in Norfolk!

It looks like this. Best I can measure is that the slope starts 6mm from the engine side of the flange and there is about 2-3mm left at the other side between the slope and the hole.
I can tell you more when I get it in my hand, if you want more?
In my opinion it's not worth bothering with. Nasher's non-chamfered one looks fine.

[Nasher]

Originally Posted by utopia

however the flange's outer profile is a little more "shaped" than Nasher's drg .

Well done Utopia, as Slob says, very detailed as usual.

I suppose I should admit at this late point that when I did the CAD model for mine I didn't in any way try to emulate the external shape of the original steel ones, for two reasons really.
Firstly because I wanted a nice clean shape.
Plus to simplify the profile and keep the machining costs as low as possible.

Then when I fitted them I realised that purely by chance I'd almost matched exactly the shape of the casting of the head where the exhaust attaches.

Nasher.

[pooh]

Thanks guys brilliant info I can now get the flanges machined ready for the new exhaust to be built.

Pooh

[Nasher]

What I must get around to doing is my plan to attempt to find some very thick wall 54mm OD Stainless Steel tube, or bar, and machine it into split collars in my lathe to replace the horrid rusty steel originals.

Nasher.

[slob]

Aha, now I can see round the back of Crust’s picture I understand what utopia means,
I won’t upload the modified file unless someone specifically requests it.

[pooh]

Nasher, I’ll have a look in my metal store I think I’ve got some material that will do if I have I’ll make some and send you a set.

Pooh