Yep, old age is catching up. Since joining about 16 or 17 years ago, the Paso/907 has aged. I have now moved into the next phase too, so have a little extra time to look at things that I just never had the time to look at. In the above time frame, I have added the odd bike to the fold, and now have 2* 750's, a 906 and a 907. And they haven't got any younger over that time, which means parts are now at a premium for all of the above. Australia just doesn't have the secondhand parts that Europe and America has. It just didn't have the market for the Paso/907. Way back in the late 80's and early 90's, they were still trying to sell the P750 as new, even though the 906 had been released and the 907 was around the corner. Finding parts means going overseas or making do with what you have. The first adds heaps to the cost due to freight and the wrong side of the road, so the second ends up being the first choice.
The latest is a coolant leak. With the 907, SAMCO hoses are still available, but for how much longer? SAMCO Sport no longer have them on their Web site, so they may have abandoned the template due to the lack of interest, or they just produce when an order comes in? Either way, not really suitable for the 906. The Thermostat on the 906 (and 907) hasn't been available for years. Various modifications are on the forum on how to get around this, but they too have aged. 5 will get you 10 the parts involved are no longer available too?
So, make do is the only real option. In my head it works. Reality may work against it, but here is my thought. It is relevant to the 907, assuming the SAMCO hoses become rare.
The coolant pipework on the 906/907 is a nightmare. There are joins on hoses that go in various directions, there is a Y piece (906) or a straight pipe with sensors imbedded (907), and the thermostat all making a horrid. To add a little variable, the system was designed as an atmospheric pressure system, not pressurised like most coolant systems. Again, mods are there to insert a cap and adaptor (from a Honda from memory?), but that means hacking into the existing hoses. Screw it up and you are done!
So, I went looking at various other water-cooled Ducati's. The ST2 is about as close the 906/907 as it gets, yet it is going down the same route. Parts, though more freely available, just flat out don't fit. I can't think of any other 2 valve Ducati that is water-cooled (and happy to be corrected!), so that leaves the 4-valve Ducati's. And found the answer!
The basic architecture of the 906/907 and 4-valve Ducati motors (up to 996 or 998?) is pretty much the same. The bottom end and cases are near identical as far as I can tell. I went the most basic and found the S4R to be the closest I could get without a transplant! It also uses the most basic of all hoses. All straight or right angle, but none with various joins or extras added. It also uses a bypass thermostat (as do the 906/907), with an extra bonus it is still a genuine Ducati part.
The only other difference I can find is the Water pump housing. The 906/907 exit pipe is vertical, while the S4R is horizontal. Again, basic architecture says an ST2 cover will fit. Clearance on the inside for the impellor will be the deciding factor here, but this will be a suck it and see exercise.
In the future the plan is to purchase in all the various bits, thermostat, cover, silicone hose to suit, and give it a crack. The existing radiator will be used and just connected up. I did consider getting a set of SAMCO hoses for a S4R and use them but going the test route to start with and keep it "off the shelf". After dissecting the flow diagrams of the ST2, the 906/907 and S4R, the S4R is the most like a standard car cooling system. There are some issues with the 906/907 flow, particularly around the flow past the sensors when the thermostat is closed. The 906 is sort of OK, but the 907 will cook if it doesn't open!
Will it work? I hope so, but as the cooling system is current knackered, then it can't get any worse!
Cheers.
Nick.
