400ex Crank Rebuild

[david kelsch]

I have rebuild two stroke cranks in the past with success. I am trying to rebuild my 400EX crank. Is the pin between the crank weights tappered, Im talking about at the ends of the pin at the crank end of the connecting rod? Do I need to heat the crank? One of my tractor technicians suggested breaking off the connecting rod and pulling one half off as opposed to trying to push the pin through. I've looked through a bunch of threads and didn't see anything on this. Does any one have any tricks?

I appreciate the website and y'alls advice

[dork]

if its like other honda 4 stroke singles, then its just a regular press fit like the 2 stroke cranks you've done. you need a pretty strong hydraulic press (20-30 ton) to get them out and heating the flyweights should definitely help. on the ones i've done it usually takes a lot of initial force to get it to pop and break loose, then it presses out a little easier.

i don't think you'd be able to use any sort of puller to get it out.

[david kelsch]

I put the crank in a 40 ton press, heated the crank weights with a cutting torch and drove the pin out. The pin can only go out one direction. There is a shoulder the oil pump drive gear rides on that would keep pin from going out that side. I didn't push it all the out.


The next challenge of course putting it back together. But that is for another thread.