How does the Aprilia RS 125 oil pump work? Installation and bleeding for non mechanics

How does the Aprilia RS 125 (Twostroke) oil pump work? When bleeding mine I was not sure if enough oil comes out of it. So I decided to take you with me on the journey to open the oil pump and see if anything is worn. Then we find out how it works, assemble the pump together and install it back on the bike. But when the pump was removed from the bike it is VERY important to bleed it. Otherwise air bubbles can get stuck somewhere in the system and your bike will run without 2 stroke oil (and the engine dies of course). So we bleed the pump with the bleeding screw and fill the carburetor with 2 stroke oil/fuel mix to let it run until the hose, which goes from the pump to the carburetor, is bleeded as well. Another method is to fill the gas tank up with 2 stroke mix, just connect everything and after one tank the hose from the oil pump to the carburettor will be bleeded. But I wanted to see if the pump works correctly so the first way was my way of choice.
We do every step together and everything is shown and explained in detail.
I hope you enjoy my video and it helps you to repair your own stuff - because thats my intention! Thank you for watching.

[@MRryuhayabusa]

Best video on the rs125 oil pump there is

[@bikedogtor1663]

dyu hi thank you, this was my goal.

[@katywalker8322]

Moving the lever doesn’t pump oil.
The pump is in effect a piston pump with a variable stroke. If you look at the bottom of the main piece it is raised on one side. The engine rotates this piece (when I counted, think it was 36 teeth on the gear, and it is driven at half engine speed - hence one rotation every 72 engine revolutions), with the edge of it resting on the shaft connected to the throttle. So as it moves over the raised side it moves up, and on the lowered side it moves down. Hence it pumps oil.
The shaft connected to the throttle has a small cam in the middle. At low throttle positions this cam pushes on a pin the the centre of the main piece, limiting the stroke, so it pumps less oil.

[@bikedogtor1663]

Very well explained, thank you. Thats in fact exactly how the pump works.

[@mils5000]

When I have to work on small high precision engine parts like carburetors or a pump like this, I do not do this in my workshop, but at my writing table. To have the best results I need to be in a comfortable, clean surrounding. Clean the surface of the items, let carburetors dry out and put everything on a plastic tablet. Also small parts do not disappear so quickly when you are working like that.

[@bikedogtor1663]

You are right, that would be the ideal way. But for me a fresh towel works.

[@MyroCraft]

Good video. Well done👍

[@t8283287]

Just what I needed thanks

[@krazed0451]

If you prime the oil pump before mounting on the bike you can prime the carburettor oil line with a drill and large flat bit ;-)

[@bikedogtor1663]

Thanks

[@RSAndy2]

Servus gute Videos was du da sehr detailliert machst!!! Weiter so würde das gleiche gerne von einer Cagiva Mito oder einem Mito Motor gerne mal sehen wie du den mit den gleichen Details auseinander und wieder zusammen bauen tust!!! Viele Grüße Andi 👍👍👍👍

[@bikedogtor1663]

Danke dir, eine Mito würde ich auch gerne machen aber die sind echt selten und zu teuer für den Spaß. Die Aprilia hab ich sehr günstig bekommen und so eine Chance kam mir mit ner Mito bislang leider nicht unter.

[@eschdler82]

@@bikedogtor1663 wie wäre es mit einer RGV VJ22B Ez:93? Das wäre für mich dann mega!😁

[@bikedogtor1663]

@@eschdler82 oh yes das wäre was

[@eschdler82]

@@bikedogtor1663 würde dir ja meine zur Verfügung stellen, bloß wollte ich sie dann wieder zurück?! 😂
Schönes Wochenende schon mal

[@ohmpere]

Nächstes Mal testen wir die Spannung der Kolbenrückzugsfeder. Danach zeige ich euch wie ihr die Leistung steigern könnt. Einfach die Kühlflüssigkeit durch Chardonnay ersetzen...

[@oopopike6383]

Is technically the facelifted Aprilia RS 125 (after 2006) the same mechanic?
Great videos, very helpful!

[@bikedogtor1663]

I haven't seen the newer one yet but those absolute standard parts barely get changed for new models.

[@flanno9]

yes the engine is the same. Some small changes with loom. You can find the updated version of the Workshop manual online. (free) :)

[@93jsaw]

i've removed the spark plug, squirted some oil in the barrel and just run the starter motor to prime the carb before.

[@bikedogtor1663]

Good point

[@darren2935]

Good video never taken an oil pump apart. to bleed oil pump I use gravity your way 👌👍

[@sergillopiscerdan9869]

¡Buen vídeo!, 😍👍

[@GoToDoAPooAtSchool9]

Do you know if the cagiva Mito 125 set up is similar? I have to undo some butchering on my bike and there’s no diagrams of the oil system available.
This looks very similar though, great video.

[@bikedogtor1663]

Thanks, I haven't touched a cagiva yet so I don't know

[@fesa_performance9617]

Von wo bist du? Österreich? Oberösterreich? kirchdorf an der krems/Nähe?

[@bikedogtor1663]

Deutschland 😉

[@fesa_performance9617]

@@bikedogtor1663 Achso wegen dem Schraubenzieher

[@deparpejpetodile6566]

👍✌