Fluid leak on my Aprilia rs50 2003?

So i recently got an Aprilia rs50 2003 and there seems to be fluid leaking from under the seat its not the oil but i think it could be the other reservoir which is i think (correct me if i'm wrong) the reserve tank which has two wires coming out of it. The lid on the reservoir seems to be quite loose and comes off easily but if i take it off fuel comes out. This is causing problems because every time i go out to it there is fuel/fluid on the panels and on the chain which i have to wipe off every time. Is this an easy fix or is it better for a mechanic to do it?  

4 Answers

  • 10 months ago

    Yes, the coolant is often green but almost always 50 percent alcohol. There should be two hoses to this transparent tank. They both have hidden vents that open at high and low pressure. The radiator will suck or blow out when it heats up or cools down. This is why it is filled almost completely (Check level, the mark is in the neck). This way the radiator keeps its fluid when small amounts are lost. Notice the reserve tank has lines on it for easily inspecting the minimum and maximum level. All motorcycles have inspection lids or gaps. In normal operating the reserve tank has no function because the vents will never open and the fluid remains practically the same. You can either replace the cap or seal the opening and older cap with a glue, as long as there is no contamination because of it in the fluid. Your statement makes me think the reserve tank for coolant is not attached and has fallen out of place. The neck should be the highest point. Sometimes the reserve tank is taken off its fixture in order to renew even the coolant it contains.

    What happens on these smaller bikes is they have a radiator on low pressure. With a relatively simple rubber or plastic cap on them and not a metal one like in cars. Those fans will have to blow cold air right at the moment the engine heats the coolant up to a certain level. For example you have been riding at speed in warmer weather and now slow. When the temperature sensor is defective (two thin wires will go to the center of a bolt in the radiator bottom) the fan will not come on and the fluid gets spilled everywhere when it boils, no matter the radiator filler cap on top of the radiator and the highest point being completely off or staying in place more or less. The radiator just can not contain a boiling fluid and even safety valves can spit it out. Broken sensors occur often and gives one a chance to renew the fluid (2 jrs or 20.000 miles and think about the percentage ethanol 50/50). Some fans won't function because there had been dust, metal corrosion and no lubrication ever, check this with a stick. I have ones been in luck with stuck blades and a silicone spray helped with lots of patience. Or else it has to be taken from the bike and restored or renewed. When fans don't turn also the fuse will fail over time because of the higher demand and then the fan will never run. I bet my money on it. The reserve tank can be full to the neck by mistake but is not in the highest place, where it can do so much harm and does not contain much. The garage floor is now being bleached for free. Wash the bike because coolant can damage paint. Best of luck

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  • Anonymous
    10 months ago

    Is it battery acid? Your battery is located under the seat. If it's clear in color and you put a tiny drop on your finger and its sour it's battery acid you may have to make the battery drain tube longer or the battery drain tube may have come loose check that

  • Tim D
    Lv 7
    10 months ago


    See if you can find the part here.

    You need to identify the fluid if it is not oil and not fuel (both should be fairly obvious) then it might be coolant or brake fluid.

    Buy or download an owner's manual find out what should be in the reservoir. And then you can think about why it is leaking.

    It would be a good idea not to ride until you know what it is and why it is leaking.

  • 10 months ago

    How does your bike work? Wet sump? Dry sump? Don't know? Don't care? Might help to get a shop manual and read it.

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