Clutch cover oil leak.
 

I previously replaced the clutch plate (plastic cover with oil filler cap) o ring as oil was leaking out the bottom of the of the plate when I first purchased the bike, however this did not fix the problem and oil continued to seep through. Some of the plate bolts are slightly curved which is unusual. I left the bike overnight on the paddock stand and when I went back to the garage there was about 50ml of oil on a paper under the bike. I am now considering removing the clutch/gear cover (where the water pump attaches to) as I am not sure whether this is somehow distorted and a complete seal is not being achieved. Anyone have any ideas on what could be causing the leak?

Re: Er, oil leak!
 

if the bolts are badly distorted it may have been down the road and the bent screws arent fully gripping/sealing, or you could have a fracture in the engine case itself

Re: Er, oil leak!
 

Best bet is to strip it back.
Check all the bolts and how the cover sits on a flat serface

Re: Er, oil leak!
 

The outer plastic cover is distorted, and the bolts most certainly shouldn't be bent, this two things are almost certainly caused by the cover bolts being overtightened in an attempt to cure a leak.
Early bikes have a completely plastic cover and distort more easily, the later curvy has metal inserts in the bolt holes and distorts less easily. Either will seal fine as long as it's not distorted.
Ensure the sealing face on the engine is completely clean and undamaged or it'll never seal.

Re: Clutch cover oil leak.
 

By the bolts are curved do you mean bent or the heads have a curve to their top surface? If second one that is normal. (but you can replace with normal skt cap M6 if you like)

Re: Er, oil leak!
 

Thanks to everyone who has replied so far. I will attempt to answer each where necessary.

I found out after purchasing that it was a cat D, but I don't know what the damage was. I today ruled out whether the crankcase is cracked.

Need to check how the cover sits on a flat surface and also need to check the crankcase breather to ensure it is not blocked.

In respect of the bolts; there are a couple of bolts that are curved, one being at the bottom of the plate so I swapped that for one of the other bolts further up in attempt to solve the leak, but no.

Can a latter style clutch plate be fitted to an earlier model? I have a '51 plate.

Re: Clutch cover oil leak.
 

You can fit cover from the gen2 which does not have easy access to the clutch. Or you could fit a factory pro billet cover. They are nice...

Re: Clutch cover oil leak.
 

Yer - I have the same problem,

Firstly the bolts, they are bent from over tightening, I know, I snapped one and bent two others by doing this without a torque wrench.

Secondly, my cover has a replacement cover with the metal bits in the bolt holes and still leaks and is straight

thirdly, I have tried a new o-ring and it still leaks

It must be the engine side of things for me and there is the odd bit of paint coming off so next I am going to stick a load of liquid gasket on it and put it back on. The oil has been in and out of this bike more times than the bike has been run - grrrrrrr - it is really bugging me now

Re: Clutch cover oil leak.
 

Don't put loads of liquid gasket on, make sure you degrease everything really well. Kitchen roll with a bit of brake cleaner on it. Then the liquid gasket has a chance. You don't need uggins of the stuff and there's much better chance it will work if you leave it to cure before running the engine.

Re: Clutch cover oil leak.
 

Yea, just make sure you know where oil level is when you do that, windows are not in same spot.