Got my s&s oil pump fitted and thought beaut that will be no more leaks. Wrong. While I had it apart I found the gearbox oil level way low so I dumped the oil and replaced it up to the bottom of the filler threads. All good. Once I started riding I had oil coming out behind the gearbox and looking around seems the most likely place for it to be coming from is the main seal behind the countershaft sprocket. After checking the manual it seems as though just about everything inside the primary needs a special tool to get apart. I hope there isn't wear in the main shaft and need a gearbox rebuild also. I wonder is this why I got it cheap? Anyone know how many of these special tools are really needed and how big a job it is to get this stuff apart? Ta.

is that a 4spd bigtwin ,? like a shovel.        filled the oil up to the filler plug  sound's too high shovels  the have a grub screw into the side kicker cover   below the filler cap threaded hole    that is the level or with the bike up straight  just around to the below the main shaft level , you might of blown a main shaft seal , but its more than like a worn main drive gear bush  & mainshaft   or could be just a loose trans sprocket main nut if this comes loose she will leak , they all do it sooner than later a bit of a leak won't hurt nothing if it's a chain drive , auto rear chain oilier ? 

Thanks daddyracer, yes it is a 4 speed shovel. I"ll have to read my manual again as i'm sure it said to fill that high. When you say fill to bottom of main shaft i presume you mean the shaft you look straight down on in the filler hole. It was putting out a puddle but if its over filled thats not surprising! I'll check for a grub screw. Ta.

The main trouble is getting to the main shaft, disassembling all the primary side. I did find today in the black gearbox outercover a black grub screw under the rear header pipe. The oil level is now right, its leaked down to the right level. So the when i go for the next ride i'll find out if its still going to leak more or not. It seemed to change gear better with all that extra oil. I've noticed the kick start slips a bit at times too so that bush is probably also worn.

hi, the rachet  gears & bush sound a bit worn if the  kicker is  slipping if it's a kick only bike make sure it's tuned well  & in good running order  ,     valve seat's  , tappets adjustment , timing etc to make it easy to start, because you will only wear out the kicker gears trying to kick start a bike that doe's not want to know about it , + could do your knee in also , i have a very nice early cast iron ( what they call a sportster knee) like you wouldn't believe,     with the trans drive sprocket lean the bike over to the right side  & look with a torch light  & @ the same time wedge a big screwdriver  inbetween the sprocket & box too see if the sprocket is loose  , main sprocket nut ,                                                                                                         all old girls need  a lot of work too bring them back too the way they use to be,  even the one's with 2 wheel's or 2 leg's it all cost $$

Ta, i' ll check the sprocket tomorrow.