oil seal yes or no

Vega 3 piece mag side bearing, is the big oil seal fitted or is the  bearing petroil lubricated

Hi Shand, yes seals front & back, bearings run in grease. The 1 piece runs in petroil & has a much bigger inner seal. Hope this helps....Steve

Thanks for that Steve

Can I assume that the Lui mag side 3 piece bearing has only one oilseal ? or should it have 2

Hiya,  3 piece is a needle bearing that runs in grease & has 2 seals.
P.S. Cranks are different also, good post in parts and alternatives..

https://lunaownersclub.forumotion.com/t242-difference-between-cranks-and-mag-housing

Thats not strictly correct, if you look at the left hand crank shown in the link, this crank is for the 3 pce. bearing, but there is no shoulder on the crank to take a 2nd oil seal that I can see, it is certainly the case on my Lui crank which takes a 3 pce. oil seal. I think on the J range cranks there is a shoulder for a 2nd oil seal, but certainly not on Lui or possibly vega cranks.

Hiya, mmm    You may well be correct as the 4 engines I've done all use the 3 piece Cranks from Starstreams. The 3 piece crank on these does have a shoulder for an inner seal lip, to prevent the grease being washed into the crank. What stops that on a Lui/Vega? Maybe some-one who has re-built a 50/75 motor could give an answer? It just seems odd, as the only references I've seen regarding 1-3 piece crank/Mag & bearing combos are bearing & seals themselves, as opposed to 50-75-125 differences?....Steve

I am in the process of rebuilding a Lui50 with a 3 pce mag bearing, there is a shim between the bearing sleeve on the crank and the crank itself to stop the inner from moving, apparently the bearing is lubricated by the the petroil mixture.definitely no large oil seal on the inner side.

Not a brilliant picture, but you can just make out the shim to locate the centre piece of the the bearing, note,not to clear but there is definitely no shoulder for a 2nd oilseal, to be quite honest I`m fairly new to these little Lammy motors, bit of a learning curve for me.

In the old lambretta home workshop manual it says the shim is to aid removal of the bearing track when using a puller

I've just done another Vega motor and there isn't a large inner seal as the crank has a flat area to allow the big end pin to be pressed in.The Starstream has the extra seal .

Hi Fellas, just got in from the garage looking for a more definitive answer & Wack has beat me to it! Looked thru my parts manuals for 75 & 125 & as Wack says the inner oil seal is for j & Starstreams. Also looked it up in the 6th editon of the Workshop manual, please see below   . Hope this helps & I now know more than i did yesterday between a 75 & 125! Still don't get that a 75 doesn't use a seal but a 125 does, considering they both share the same bearing  
 

shand wrote:In the old lambretta home workshop manual it says the shim is to aid removal of the bearing track when using a puller

Good point, that makes more sense,