Hello I have another problem with my bike, now only when it is running oil streams out of a threaded hole right in front of the sprocket. Looking into that hole I can see the clutch actuator rod. Is there supposed to be a bolt in this hole? Like I said it is threaded but the flywheel cover does not have a bolt that goes into it and there was nothing in it when I took the cover off. I was able to slide the clutch rod out but I don't see a seal or any way to replace a seal down the hole. I don't have a service manual but would like to know how to go about replacing the seal.

Here's the service manual: www.yamaha-enduros.com/index.php/service...ctory-service-manual

Sounds like the accentric bolt & nut are missing for sure. It lifts or lowers the arm which in turn increases or decreases your free cable to the lever. It sounds like you're riding it like it is & could quite possibly work if the cable is within limits to lift the clutch. Check the level of oil in the trans too or drain & put the right amount in & don't immediately rely on the dipstick untill its had time to level out right through the cases.

Ok back to school for me--i'm telling porkies looking at the link. Yours has a straight stepped locating bolt & adjusment is done on the pressure plate. So you could possibly make something to step into the groove just not too deep so it bottoms out in the groove & stop arm moving. #25 & #26
www.partzilla.com/catalog/yamaha/motorcycle/1977/dt400d/clutch

Clutch Arm Seal Video  
This video may have some info that is helpful.

Pretty sure if I remember my 77 that the lever is finally on top on the 250/400 (where it should be! lol).  Same basic operation as in the video except no goofy "eccentric screw" adjuster that lifts and lowers the lever. 

The screw on the 77 is just a retaining bolt that needs to be removed to pull the lever and shaft up out of the case on the 77...  internal adjustment requires clutch cover removal on the 77-on.

Oil is coming out from the missing retaining screw i linked to partzilla in post number 3. That my understanding of the problem.

I think it is unlikely that this bolt fell out because I have not ridden this bike much and it wasn't leaking after the last ride. It started leaking while working on it in the garage, also the flywheel cover probably would have stopped it from backing out right? Or caught it when it did fall out? I think it never had this bolt while I have had it. Shouldn't a seal prevent oil from leaking out? Or will it be fine by just getting a bolt for the hole?

Read the answers...  especially from RT325. 

If you were able to pull the lever and shaft the cable attaches to up and out of the engine case then you are missing the special retaining bolt that goes in a hole in the case in front of the sprocket.  It's short and I doubt the cover would prevent it from falling out.  Parts diagrams were linked in previous posts. 

It's your bike though and we can't see what you're working on so do whatever you want.

Seal wouldn't stop that leaking from the screw hole if screw is missing.
Seal is at the top of actuator so oil is in & around the actuator part.
Missing screw probably has a sealing washer of sorts & thickness of washer calculated into the length of the pin piece on the screw so it doesn't bottom out in the actuator groove.
Ok i cheated & had another look & #26 they call a gasket so will be a soft reasonably thick washer.
Have a look under the bench & your missing screw might be there.
If ya keen to go riding-- what i'd do--& i should give bad ideas--is just find a short bolt or screw & cut it even shorter after looking at how many threads are in 'that' hole & make it 'that' length so as not to go in too far & push on the actuator.
Just to block the hole while waiting for a genuine one.
I hope the thread in the hole is ok!!
Sorry--i got a bit carried away there.

Try posting pics through "imgur" or similar. We love pics. Link below.
Looks so good i might start using it.
imgur.com/