Aprilia RS125 Oil Leak Problem

[jinxy88]

Well I have been working on the RS125 and nearly ironed out all the small problems with it that BCF has helped me out with. Even took it for a spin today and seemed to be working fine.

Problem is I keep getting this re-occuring oil leak which only seems to start when the bike is warm and I havent much of a clue what the problem is and not sure if I want to attempt it.

Below are some pictures from the workshop manual that I used to show where the oil is leaking from:

https://i31.photobucket.com/albums/c369/jinxyrs125/leak.jpg

The bike seems to be running ok apart from this leak, but I do not want to ride it in case it causes more damage so any ideas on what is causing the leaks or some advice from some more mechanically minded people would be great!

[bidman]

Hi, looks to me that the gasket has gone on the engine casing, replace this and it should be ok.
Dan
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[Kickstart]

Hi

Leak from the bottom may well be the gasket. Check it isn't the oil drain plug, or possibly one of the plugs on the clutch cover leaking (the ones for adjusting the clutch).

Not sure why it is pumping oil out of the clutch cable. Only thing I can think of is the gearbox is getting pressurised. Possibly from the gearbox being overfull, or possibly a leaking clutch side main bearing seal.

All the best

Keith
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[jinxy88]

Ok, thanks for the pointers.

I have heard same things for explainations of why it is leaking like it is but I think it may be a job for the garage this one... but will post back once the problem is fixed.

[keltow]

7 years have passed.... (and no answer )

I have exactly the same problem and this is the only website on google which discusses the problem.

I read the comments, so I replaced all the gaskets and oil seals.

The clutch cable is still leaking oil... It also leaks when the engine is turned off while it is still hot.

Could there be a vacuum accumulating in the gearbox ?
If so, How to get rid of it.

Did I mess up replacing the gaskets (again?) and I have to do it again ?
If so, how can I make sure the gaskets are installed correctly. There isn't much to do wrong, is there ?

I always use a small amount of liquid gasket on the paper gaskets.
There is aprox. 600cc gearbox oil.

[stirlinggaz]

hi,
dump gear oil, remove side casing & replace the gasket. refill/replace with lite gear oil.
oil 7 quid, paper gasket the same iirc. takes 15mins with a set of hex keys.
other issue..(clutch cable)..pass..
cheers,
GAZ

[Robby]

Assuming the clutch cable disappears inside the casing, oil is only going to travel up the casing with a bit of force and/or capillary action.

Capillary action first. Easiest way to get this going would be to overfill the gearbox oil. Did you make a silly mistake like checking the oil level with the bike on the side stand? Oil level needs to be checked with the bike upright.

Pressurising next. I suppose it is possible for the crank seals to fail and pressurise the gearbox, then for this pressure to escape up the cable. This would assume a seriously blocked breather (assuming it has a breather). You would also get some white smoke from burning gearbox oil - if it's pressurising the gearbox at one point, it's sucking on it at another point.

One brief sense check though - the oil is definately leaking from this cover? You're not seeing an oil stain on the floor from melting chain lube sludge and being suspect?

This may be the first time someone has resurrected an ancient thread with a question that fits. Nice work.

[keltow]

I had to fix my computer so I lost this forum. But I found it
I hate to see a topic not having a solution to the problem.

Fixed!
I made a small video about the mistake made.

There was an engine leak not from the gaskets but from the ''seals''.

Explained in video:
https://youtu.be/SYUxFVJQ3Ug

I hope this would help others with the same problem
.

[sakke68]

Hi, I just did a total rebulid of my Aprilia RS 125 2004 and got an oil problem instead of a lot of fun hours in the seat.

The engine are pressing oil out from the clutch wire entrance and through the seal around the shifting shaft when it reach full working temperature. I have new o-rings around the clutch wire end, it should´t leak because of that.
All bearings, gaskets and sealings are new.

There was a video in this thread before bit it´s gone now.
Any one as know what the solution was?

I think it can be the ventilation of the crank case as is blocked.
Where do the ventilation tube enter in crank case, is it behind/above the inner balance shaft bearing?

Update 2019-08-09
Problem solved.
Crank case ventilation was blocked by the inner bearing to the balance shaft. It had the seal left on it´s inner side, that will block air to reach the inner area in the crank case.
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