Laverda LB/1 125

romeo

romeo

New member
Location
Gommiswald, Switzerland
Hello
Does anybody know how much oil I need for the gearbox of my LB/1 Custom?
If I fill up until the screw on the right side the oil comes out of the breather-screw that secures the cickstartspring.
Thank you much for your help.
Romeo
 
1,5 liters
A screw next to the tacho drive on the right side engine cover is for checking gearbox oil level.
The same screw can be used to fill the gearbox. The screw has an o ring.

-Jouni
 
Hello Romeo,

I would start checking if it is rising pressure to the gearbox. Crankshaft oil seal on the primary side or gasket between engine cases may leak.
If not this can be something else.

-Crankshaft oil seals need to be made of Viton. They strangely have no surface that stops them, they just need to be fitted straight and to correct depth.

-Gearbox oil seals can be made of nitrile rubber.

-After a new gasket is fitten between engine cases, it needs one retightening after a couple of thousands of kms. Some screws are are on the left side of the engine, some on the right side, some are under the magneto and some are under clutch cover.
If the gasket is gone I think retightening is likely not going to fix it.

-If the engine cases are opened, there is a spring in the gearbox that can not go in place if the parts are not assembled "wrong way" to the left half.

The engine is tricky in this model and has a lot of other things too.


-Jouni
 
I don't know the intricacies of this particular two stroke but from my experience a leaking crankshaft seal is very likely to show itself with suction into the crankcase chamber, as they have very strong negative pressure in the crankcase. We used to check this by using (I can't remember the name) very distinctive smell two stroke oil in the gearbox and going for a ride, if you could smell it from the exhaust you knew you had a leak to the gearbox. On the dry side of the crankshaft you usually had already holed a piston as it had been sucking air. The gearbox has to be vented as well, or it will build pressure, have you checked that your vent is not blocked Romeo?
 
I remember from my two stroke times if the oil seal at the crankshaft is leaking or the seal between the cases, the engine will suck the oil from the gearbox in the combustion chamber and you will see it at the exhaust. A lot of smoke will come out, much more than usual.
Andre
 
If I recall correct the primary side crankshaft oil seal is originally fitted spring side towards primary.
This is possibly because a leaking seal is then more likely to leak out than in, fuel and air to the gearbox is less bad than extra air and oil on the engine.

Here are the dimensions for the crankshaft oil seals:
Magneto side: 20 X 30 X 7 Viton
Primary side: 28 X 40 X 7 Viton
Both are originally double lip type, but I have used single lip seals as well in two stroke engines.

-Jouni
 
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