Hi - I’ve replaced the LH crank seal and now due to not being able to find a slight leak when performing a leak down test, am planning to replace the RH crank seal.
I’ve never done that before.
Are there any good videos to watch before I attempt it?
Apart from the seal and gasket, is there anything else I should purchase before I start?
Also, should I do any other jobs while I’m “in there”? Replace any clutch parts for example (the clutch does seem quite ‘heavy’) that wear out.
I’ve not ridden the bike yet (still restoring it) so don’t know what actually ‘needs’ to be done.
Many thanks.

Heavy clutch is more often that not the cable & you sure can't beat a new & lightly lubed cable.

Thanks. Yes, I bought a new cable, but have not yet fitted it.
 

Hi - does anyone know where I can buy genuine Yamaha crank seals (DT400 twin shock) in the UK?Also, when installing them, should I ‘grease’ the outside surface of the seal (where it mates with case)?
Thanks again….

JammyYammy - hello from the colonies

My DT360 and DT1E both had an o-ring under the primary gear on the crank that you should replace while you have it apart, assuming your 400 has one.

When I had 360 apart I changed the clutch disks with a Barnett kevlar clutch kit because the disks looked crappy.  On the DT1E the disks looked good and were at the top end of thickness spec so I reused and glad that I did.  New clutch cables in both cases

good luck! 

I grease all seals to fit them to help them slide in without damage. Others may disagree.

Don't forget to apply some grease or vaseline between the inner and outer seal lips ,
( where the crankshaft will sit ) .

Crank seals should be available at your Yamaha Dealer.

Thanks to all.
I bought genuine Yamaha crank seals from tytrials in the UK.
They also include the O-ring (thanks also to Msavitt).
They also recommended greasing the outside of the seal (thanks also to RT325).
 

My clutch is so heavy it actually spoils the ride, I did replace the springs for new, can’t remember if HD or not, will have to check. Cable was free and smooth when not use but is old , so looking for a new one.
I would really sort it before finishing your build, I actually hold back from riding because it’s so heavy  .