Hey Guys,

Just a quick question I was planning on relocating my Coolant overflow tank which would mean making a custom tank, does anyone know the volume that it needs to hold? I've only found one site that says its 0.4L, but does anyone know if thats correct?

Thanks
DBRMN

I am using a baby bottle with a nib taken out of the rubber tip, cable tied to a right hand frame rail. It holds maybe .4L and does the job as intended. There's only an inlet and the coolant volume never changes. Check these out:

eBay coolant bottle



I've since moved it back just inside of the frame rail where it's more secure.

Two Wheels Better wrote:I am using a baby bottle with a nib taken out of the rubber tip, cable tied to a right hand frame rail. It holds maybe .4L and does the job as intended. There's only an inlet and the coolant volume never changes. Check these out:

eBay coolant bottle



I've since moved it back just inside of the frame rail where it's more secure.

Ah thats interesting it looks surprisingly good, how come you don't need an outlet?

I was thinking of using those mounting points where the old air intake pipe went on the radiator?

As I said, the coolant water volume never changes, which means as things work as intended you only need to secure the potential few drops that may arrive in the bottle at times. I've travelled possibly a thousand miles with this set up with no issue. Your original tank does not contain a feed and return.

ETK coolant system link

Two Wheels Better wrote:As I said, the coolant water volume never changes, which means as things work as intended you only need to secure the potential few drops that may arrive in the bottle at times. I've travelled possibly a thousand miles with this set up with no issue. Your original tank does not contain a feed and return.

ETK coolant system link

Oh ye I was just having a look at the pictures, so why is it located at the bottom? does it use that to vacuum more coolant back to the radiator if it needs it? Cause that makes fabricating a new one a lot easier. What do you do it terms of it pressure is built up, do you need a hole for it to breath?

So you see the design is a simple overflow and reversing pressure is never a part of how it works. The pressure is all on the inside of the radiator under that mighty mighty cap. If it ever feels the need to burp its guts, as little scrubbers often do, it does so into the chamber, the little catch all. I reckon a baby bottle is apt.

does it use that to vacuum more coolant back to the radiator if it needs it?

Yes, the radiator cap works two ways.  If there's too much pressure in the cooling system it will "blow" at 1.0 bar.  When the system is cooling down it sucks in new coolant as needed at -0.1 bar.

Good to know those specific details, Duck. By my error and dumb luck when I fabbed it up I made the hose long enough going into the baby bottle to rest at the very bottom so it continues to do what it needs to do.

As another example of how these things work, the Audi I drive has a pressurised external tank with cap and it ebbs and flows as required into the main radiator which does not have a cap for filling.

Ye I've heard about the fancy nature of the Radiator Cap. Ok that sounds sensible enough, so I need a 400-500ml capacitance to be on the safe side, and a single inlet/outlet hose preferably at the bottom or reaching the bottom of the tank. Easy, hopefully. Going to see if I can get it fabricated out of ali.

Much like this but the other side (little grey box),

Just in case anyone was curious this is what i've ended up going with, it has a capacitance of 408ml which i think should be enough. Here is a mock up I made and my drawings,

You've got to love cardboard and tape design. Over the years I've made a cardboard and balsa scale bike lift, a full size cardboard petrol tank and a full size cardboard engine. It's a lot easier to position a cardboard engine than a metal one.
Regards Martin.

MartinW wrote:You've got to love cardboard and tape design. Over the years I've made a cardboard and balsa scale bike lift, a full size cardboard petrol tank and a full size cardboard engine. It's a lot easier to position a cardboard engine than a metal one.
Regards Martin.

Oh my god I don't even want to think how long that took you, that box right there took me an hour   . You can't go wrong with a cardboard technical drawing, though mines the furthest thing from technical lol.

I'm sort of sorry I didn't keep them or at least take pictures. However I still own the end result. I made the prototype tank out of carboard so I could get the tank right which ended up requiring two pieces to be folded. The cardboard engine (Villiers 150cc) allowed me to play with mounting angle and positions. The cardboard parts allowed a lot shorter and easier build time.


Regards Martin.

MartinW wrote:I'm sort of sorry I didn't keep them or at least take pictures. However I still own the end result. I made the prototype tank out of carboard so I could get the tank right which ended up requiring two pieces to be folded. The cardboard engine (Villiers 150cc) allowed me to play with mounting angle and positions. The cardboard parts allowed a lot shorter and easier build time.


Regards Martin.

oh wow that looks like a really fun project, it looks so good, how long did it take u?

It took me about 12 months, the hardest part was getting the pulley system to line up. It ended up being .005" out of alignment. The idler pulley had to be custom made as did the rear pulley and spoke clips. All sorts of weird and wonderful parts went into it. The engine was originally full of mud wasps. The cutdown quadrant for the drive was out of a washing machine, an air rifle spring, a brass fuel cap of a rusted out mower tank and a genuine Lucas Road king headlamp $10.00 of Ebay. Top speed is 40KPH on the flat. It used to be legal to ride on the road, but the QLD government eventually banned petrol driven bicycles due to idiots fitting larger HP engines than allowed.
Regards Martin.

MartinW wrote:It took me about 12 months, the hardest part was getting the pulley system to line up. It ended up being .005" out of alignment. The idler pulley had to be custom made as did the rear pulley and spoke clips. All sorts of weird and wonderful parts went into it.  The engine was originally full of mud wasps. The cutdown quadrant for the drive was out of a washing machine, an air rifle spring, a brass fuel cap of a rusted out mower tank and a genuine Lucas Road king headlamp $10.00 of Ebay. Top speed is 40KPH on the flat. It used to be legal to ride on the road, but the QLD government eventually banned petrol driven bicycles due to idiots fitting larger HP engines than allowed.
Regards Martin.

Oh wow that sounds like an amazing project, I always find it fascinating when people reuse parts to fulfil completely different tasks. Very well done its such a shame you can't ride it on the roads, but I'm currently suffering something similar being 18 i won't be able to ride my k100 for another 3 years

DBRMN wrote:Just in case anyone was curious this is what i've ended up going with, it has a capacitance of 408ml which i think should be enough. Here is a mock up I made and my drawings,

That is brilliant. I was trying to figure out where to relocate mine. I hope you consider it sincere flattery if I do something similar to what you've done.

Vitamin K wrote:

DBRMN wrote:Just in case anyone was curious this is what i've ended up going with, it has a capacitance of 408ml which i think should be enough. Here is a mock up I made and my drawings,

That is brilliant. I was trying to figure out where to relocate mine. I hope you consider it sincere flattery if I do something similar to what you've done.

Absolutely feel free I'll keep this thread updated, I've turned on the lathe a cap and have ordered a barb for the inlet/outlet:

So brief change of plan, it turns out the method I used to construct the box is way to complicated to weld. So instead I made the outside edge all one piece and then just attach a front and back plate.

Here are some pictures of it all welded up:


It still need's tidying up, but the top cap still needs to be tapped, the inlet/outlet needs to be tapped, and finally the last edge needs to be sealed. But otherwise its close, one done I'll be going over the welds with filler to make them flat and smooth then giving it a coat of black paint. Here's it next to the bike:



And a picture of the inlet/outlet location: