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Discussion Starter · #1 ·
Do these bikes really need the coolant bottles or can they be run without one without any hassle or ill effects?
 

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good question. i would leave it be though. the cooling system is over 30 years old and capping off the overflow might have some ill effects. if you're worried about the coverflow res. being fugly i am making one that doesnt' look as bad. either way i would leave the system alone w/ intact overflow
 

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As I have a longer than standard Eurosport motor in a 78 frame

its something I've experimented with and as said

Its best to have it or something like it.



To be precise, its not a reservoir exactly, but an expansion bottle to hold the

coolant when it expands as the motor gets hot.

The rad cap has a two way valve that allows coolant to get drawn back again when the

motor cools down and the coolant contracts.



It is rather Fugly isnt it? I put mine down inside the crash bars

where no one would notice it


 

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Discussion Starter · #5 ·
That's a drag as the bike I just picked up doesn't have an overfllow/reserve tank and from what I understand they are real buggers to get out much less back in. Any suggestions?
 

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You could probably rig up something that would do the same job and be easier to put in place. I'm thinking a plastic dish washing soap container or shampoo bottle. Probably a pint size would be large enough. Then run the overflow hose thru a snug hole in the cap to the bottom of the bottle and add a second overflow hose as well. As Reg says, this aint rocket science. It is just a place for maybe 4 oz of coolant to expand to when it gets too hot. And then be drawn back into the cooling system when things cool down.



Walk thru the grocery store with an idea of what size you can easily get in there, and if you can find something with a flip top, that would even be better.
 

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You might get away without one all other things being equal

but as they say

'Its better to have it and not need it than

need it and not have it'

When I fixed my head gasket I filled the rad until my boots got wet

then caned it down the ring road for half an hour

I saw the level rise about half an inch and settle about the same later, thats all

( hot summers day, fast A road and then busy traffic riding)



Previously I had a length of pipe dipping down to the level of the missing bottle

and routed up to the top of the rear shock.

If my motor hadnt been puking coolant like a dog due to bad head gaskets

it may have been enough to hold the amount needed.

( in normal use of course)



A loop of pipe with coolna in the bottom is functionally the same as a bottle

theres no pressure from the rad, it just assists any siphonic action

if your rad emits coolant.



By the way

I closely examined my rad cap way back and it does have a small return valve

to allow coolant get drawn back

Not sure if aftermarket ones do
 
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