Crank work?

[1976RD400C]

I've done lots of 400 cranks if anyone needs one done at a bargain price.

Where in NY are you located? Might have to take you up on that

Albany

[Tommo]

Post some pictures so we can commiserate.

It's probably not that bad. Unless the bearing surfaces are heavily rusted/pitted it can almost certainly be saved.

Yeah IDK where I'm going with this.  I have two motors.  An R5 with a good crank but questionable cases and an RD with a sh*t crank and good gearbox but a terrible crank gallery (though the bearing mating surfaces look okay). 

I'm tempted to throw the R5 crank into the RD cases, that saves me moving the transmission bits around.  But the crank gallery over there is atrocious.  The R5 cases, the cylinder hold-down bolts are severely perished and I'm afraid to take them out because they seriously look like they'll snap right off.

I'll try to post pics later, I have a laptop and all the pics on the phone.  Edited:  Pics from L to R, RD crank, R5 cases, RD cases w/ gearbox, R5 crank.

I guess I'm just looking to find out where to put the R5 crank because I need to get the right seal kit.

[1976RD400C]

I took one that was rusted like that and after it was apart chucked the flywheels in a lathe and took a few passes and knocked the rust off. It still won't look pretty but salvageable as long as the surface where the small seal on the alternator side isn't pitted. Yambits has rod kits at $56 each and a set of main bearings for about $100 (don't know if tariffs will raise price).

[sav0r (CL MotoTech)]

That crank isn't terrible. I'd try some emery cloth and Scotch Brite. It doesn't have to be pretty. A lathe helps for sure.

The trick to removing these old case studs is to double nut them and hit them with the impact. They usually come right out. The impact is the key. They won't budge without it.

[Tommo]

The R5 crank is dead nuts on, less than 1 thou, one big end bearing might have a little bit of end play but it's not terrible. The R5 motor was on the original bores, probably low hours.
I might take a shot at the RD crank; I have time and I can't make it worse. The crank pins need to be ground off to get it apart?  And is a 12 ton shop press enough to press it apart?

[m in sc]

nothing needs to be ground . it should just press apart

[sav0r (CL MotoTech)]

I have both a 12 and a 20 ton presses. I usually use my 12 ton. It's nice and square and since the ram is smaller OD and longer it's easier to work around cranks.

[Tommo]

nothing needs to be ground . it should just press apart

Yeah unfortunately for me the pins are welded in.  On both sides.  It also has aftermarket rods. Racebro thought he was dealing with a 100hp bike or something, IDK.

[bitzz]

If it's already been welded, you need someone that actually knows what their doing to try to rebuild it.
It MAY have been welded because "Racebro thought he was dealing with a 100hp bike or something,..." OR it was welded because it was loose when it was last taken apart.
We were talking about what press to use... when I take them apart, I find they take (IIRC) 5-7 tons to press them apart, and they POP when they come apart... That's a good one that can be pressed together. Then OTHER ones take a couple of tons and just kinda smooosh apart... THAT one gets welded.
If done right, just grind out the weld, and start again. There shouldn't be GOBS of weld, you only need a tack or two.
I have often said that anyone with a brain and a press can rebuild cranks... then I saw some of the abortions done... so I have to retract that statement. I have seen new, aftermarket cranks that had to be trued. Rebuilding cranks is simple, but kinda finicky... I guess it takes practice.
Use stock RD400 pins, they're serrated, so they hold better. Wiseco makes hollow pins if you're doing a performance motor. Wiseco and Suzuki offer silvered big end bearings. ProX rod have a split big end, like the TZ rod, that oils better... again IIRC (I don't do a lot of RD350s, I'm a TZ or RD400 guy)

[m in sc]

id just buy a new crank at this point. 

[Tommo]

Yeah I'll just use the other one I have. 

[1976RD400C]

I noticed the last 400 rod kits I got from Yambits are Mitaki and come with the lower bearings that have more rollers, like the RG500 type.

[m in sc]

also make sure the r5 crank hasn't spread over the years. make sure the end play at the rods is ok.