this is not a fun one
the engineers at honda designed an oil seal that originally pressed in from the inside of the case with a stop-lip to limit it's seat depth.
to get a replacement OEM seal with the lip in requires splitting the cases and replacing it in the same way, from the inside out
OR
you can carefully remove it and replace it with an aftermarket seal from the outside in.
we choose option B
a seal puller with a sharp narrow pull head like this one will do you fin
a.co/d/5AGNko8
the seal kit used to repair this bike is a Prox 26.640008 which retails for $14.36
please let us know in the comments if you have a better procedure for this job
a few comments we know we'll get:
* chain is too wide and rubs on the case. we know. we intentionally installed a long lasting x-ring 520 chain and it's wide enough to slightly rub on the case a bit. once it's made it's own clearance that issue is no longer an issue.
*the stop-lip on the old seal prevents the case pressure from pushing it out. in an extreme situation that's true, one where the crankcase vent hose had become completely blocked and the engine was in a high blowy condition from being clapped out with overly worn rings. this would be motor burning oil and down on power and crying out for a refresh. if all that happened at the same time the seal could push out and your right foot would be covered in engine oil, but that's not the only seal that would blow out so you'd be death by a thousand cuts at that point.
if you need anything that we an help with on your 19+Honda CRF450 L, RL or X please let us know.
702-812-6626
mike@tacomoto.co
tacomoto.co/