For best results, I recommend engine disassembly for installation.
While not mandatory, cleaning of crank and bearing surfaces along with blowing out with compressed air ensures a debris free environment for installation.
Installation shown below shows front ZeroDrag Seal installed with engine assembled and rear ZeroDrag Seal installed with engine disassembled.
Engine shown is from a GSR40.
HRS ZeroDrag Seal insert in my hand.
Clean the crankshaft and crank seal prior to sliding ZeroDrag Seal Insert on crankshaft.
Press into seal and your are done.
This engine is broken-in and easier to do than an new engine.
If seals are too tight, disassemble engine and push in.
Completed seal insert on front side of engine.
Same process for the rear seal.
This one was a little tougher. Don't force if resistance is felt.
In this case, I disassembled engine and pressed in.
It's much easier this way, but more time consuming.