Hi folks.
First- thanks to John and the 907ie tech forum. The reservoir bottle redesign was fantastic.
Second- I wanted to share my experiences and the modifications that worked for me:
I removed the whole of the Y valve hose and replaced it with a single new one from an automotive parts store. No problem.
As the hose passes close by the back end of a frame bolt, I cut the end off of a vacuum plug and stuck that on the screw for abrasion protection.
As my rewervoir tank was badly cracked, I thought I'd give plastic welding a try. The material is polyethylene and nothing sticks to it. It cannot be glued. If the material is gently brought near- not to-surface melting, it can be joined with the addition of similar material. If it is melted and pools, it will not work but rather will drop away as a melting wax figure. White food grade cutting boards are said to be similar material, as are some drink containers and glue gun sticks. I sliced some pieces off of a cutting board and used that. It seemed like it worked but eventually the fluid leaked around the "fix" and I could snap off the cutting board material. I tried again with glue gun stick and it worked fantastically. One might say that the polyethylene in the glue stick is very similar to the material in the coolant reservoir.
The other significant observation that I made was that the Honda part recommended as a replacement has a cap identified with the number 1.1- as in .1 bars of pressure for the release valve. the black reservoir cap indicated .9- a 10% difference. If the plumbing of the system is overbuilt there is no problem, but if your hoses or clamps are not in good order, the extra pressure might lead to new problems. I sourced a new $8.00 .9 bar cap at Canadian Tire. It will be similarly available at your local auto parts supplier.
The fix looks like a gem. I'l be testing it out on the road tomorrow.
Again, thanks for the tech analysis and having an easy to follow plan for retrofitting the system.
Sheldon

Hi Sheldon, I have not been able to source a .9 bar radiator cap locally, I have tried auto parts stores and motorcycle dealers. Do you have a manufacturer and part number or a model that uses this rating?

I did the conversion on mine last week using the Honda fitting where the Y hose was. I used the 1.1 Bar radiator cap, but did not reuse the Ducati tank. I used a KX250 Kawasaki tank which fit in the same place just fine. I have had no issues with it and the temps here have been close to 90 F.

Preston

Hey Shelboss-

I happened on the .9 rad cap quite incidentally. It was on the rack of cheap radiator parts at Canadian Tire. I gather you are an American. Canadian tire might ship the part, I don't know. Try: canadiantire.com. Otherwise I think it should be available at some sort of low cost parts supplier; Pep Boys or whatever.

If you can't find one locally, let me know and I'll pick one up for you and pop it in the mail. It fit my Honda coolant neck perfectly. If you want to go that route, send me your full address: smseigel@shaw.ca

Sheldon

Hi Sheldon, thanks for the offer! I figured out that if you ask for a motorcycle radiator cap at the auto parts store, they do not comprehend. The 13 psi cap is actually used for automotive and motorcycle applications, just look for a Stant #11227 or equivalent. It was $8 in the States also. I will update the tech article with the hot melt and cap suggestion, thanks!
Art

I know! Isnt that cool when you get to the counter with a part in your hand and ask if the clerk if they have "something like this" and they say: "What's it from" and you tell them and their eyes glass over? I just won't tell any more. Now I walk in for a Ducati Scrambler part or a Paso part and ask for "one of these" and the clerk says" What's it from?" and I say: You don't want to know. Would you please go back there with it and ask someone older and pretend you forgot what I said it was from? And then the clerk comes back and says: "They told me to ask again." And then you know the person in the back is also 19 years old. Nothing against 19 year olds (I have one myself), but I remember when an auto parts place had boxes of stuff and if you asked for "one of these" they would go back there and find one. Now if it doesn't have a part number, is not listed in the computer, was not built in the last week and a half, and is not completely self described by a bar code or inscription on the part- the answer is "oh no, we don't sell those. I doubt anyone can get you one of those." I once brought my nineteen year old in to the Canadian Tire auto counter to prove the same point to him. I handed the clerk a plastic tire valve cap and asked if he carries these. He said: "what's it from?". I tried to supress the laughter- but my son burst out. I said: Michelene 225/50 17 with a straight face and then my son (who was doubled over grasping his abdomen) said: "front left!" and cracked up again. The clerk offered a sarcastic laugh himself and then said: I know its a valve cap, right? And I smiled. But then my son- I don't know, he just could'nt control himself- added: "but it's metric!"

...........

Yes, you are right. Next time I have the faring off (soon, I have to re: and re the speedo cable) I'll do that.

Sheldon

If the clerk behind the counter absolutely needs an application for a .9 BAR small radiator cap, tell him 1997 Mazda Miata. After all my hunting around, all I had to do was open the hood of my daily driver, Doh