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Discussion Starter · #1 ·
Team, I am building a 1982 CX500C into a Street Tracker similar to the Rive Gauch Kustoms bike and would like to remove or relocate the Radiator Overflow Tank. My ulitmate question is if we really need the radiator overflow tank for normal riding around town and cruizing down the highway if the fan is in good condition and Radiator is full?

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Discussion Starter · #2 ·
Or another way to approach this is what is the risk of running the overflow hose into a bottle attached to the side of the radiator or hidden where the existing one is?
 

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You do need a bottle of some sort as it is designed as an expansion/recovery system, make sure whatever bottle you use that a) it holds enough and b) the pipe to the radiator enters the bottle at the bottom, and c) the bottle can "breathe" to atmosphere.

Running without a bottle will result in a continual need for topping up the radiator and the bike leaving puddles here and there.
 

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And the puddles of antifreeze are toxic to small animals who drink it because it smells and tastes sweet to them.

Check out radiator overflow bottles on EBay....here's an example similar to what's on the bike you want to emulate except for the color:

800ml Cylinder Radiator Overflow Reservoir Coolant Tank Blue Aluminum Can | eBay

You would have to add a fitting in the cap or high on one side for an overflow hose.
 

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In San Francisco it's chilly year 'round and outside temperature rarely gets above 70 degrees F (21 degrees C) so my motorcycles run cool. I don't think any significant amount of coolant has ever blown into my expansion tank on either of my GL500s. Tank is always at the same level with the same scum line inside. I say ditch the overflow bottle and run pure water. Put antifreeze in it when you winterize it.

Regarding the fan, have you considered ditching the camshaft mounted stock fan and replacing it with an electric fan? I've not done it myself but there are many success stories on this forum about the conversion and nearly all the rider who have made the switch report better engine temperature control.
 

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In San Francisco it's chilly year 'round and outside temperature rarely gets above 70 degrees F (21 degrees C) so my motorcycles run cool. I don't think any significant amount of coolant has ever blown into my expansion tank on either of my GL500s. Tank is always at the same level with the same scum line inside. I say ditch the overflow bottle and run pure water. Put antifreeze in it when you winterize it.

Regarding the fan, have you considered ditching the camshaft mounted stock fan and replacing it with an electric fan? I've not done it myself but there are many success stories on this forum about the conversion and nearly all the rider who have made the switch report better engine temperature control.
Dash, love your avatar man!
 

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Discussion Starter · #10 ·
In San Francisco it's chilly year 'round and outside temperature rarely gets above 70 degrees F (21 degrees C) so my motorcycles run cool. I don't think any significant amount of coolant has ever blown into my expansion tank on either of my GL500s. Tank is always at the same level with the same scum line inside. I say ditch the overflow bottle and run pure water. Put antifreeze in it when you winterize it.

Regarding the fan, have you considered ditching the camshaft mounted stock fan and replacing it with an electric fan? I've not done it myself but there are many success stories on this forum about the conversion and nearly all the rider who have made the switch report better engine temperature control.
Gents, I am not concerned about the criters as I do not feel that it will get that hot to over overflow the radiator especially with the fan on all the time. I like the flask Idea and may go that route also. What advantages does the electric Fan provide?
 

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The elctric fan will only run when needed (saves a bit of load on the engine) alowing the bike to reach and maintain operating temp better than a mech fan. It also work really weel regardless of the bike RPM (as in "stuck in traffic"). I found that after I installed an electric fan, the bike basically sits at the same temp regardless of ambient temp, riding speed or being stuck stationary for hours.

As for running plain water, I would never do that as water has a crappy cooling co-efficent compaired to antifreeze/water mix (its not just there to prevent freezing, its there to change the boiling point of the coolant). Have seen many an engine destroyed by using only water (which should be distilled unless you want a "lime farm" inside the engine and rad).

As for the overflow bottle, I would keep it if it were me. It can be located basically anywhere you want (as the fluid movement in and out is via pressure differentials and not gravity), and can be any form of container (just make sure the hose from the rad extends to the BOTTOM of the vessel, and the top is open to atmosphere).
 

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Team, I am building a 1982 CX500C into a Street Tracker similar to the Rive Gauch Kustoms bike and would like to remove or relocate the Radiator Overflow Tank. My ulitmate question is if we really need the radiator overflow tank for normal riding around town and cruizing down the highway if the fan is in good condition and Radiator is full?

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What are you thinking of using for the small headlight? I've been looking and haven't turned one up yet.
 

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Don't ever just run water, deionised or otherwise, the antifreeze is not just to stop freezing, it contains corrosion inhibitors, without these your engine insides will corrode crazy fast and give you all sorts of issues.

Losing the stock fan is good news, it is not needed all the time yet you waste energy/fuel driving it all the time as it is fixed to the camshaft. I have a small electric fan on mine and a thermoswitch in the lower radiator tank.
 
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