The 500 engine has leaky oil seals (O rings) between the cylinders and the head on both sides.
Be sure to get a clutch cable mount for the upper rear engine mount if you go with the 500 engine, the 550s don't have them.
Q: If you already have 2 550 engines why dick around with the 500?
I didn't see a thorough engine exam there, on any of them.At very least you should have removed the oil pan to check for peices, grindings and primary chain stretch... Open it up , take a look at those valves and those over 40 year old seals, see if the valves are stuck or free. do the valves seat well? Then take a look at those pistons and the piston walls ,are they scored ,within spec? Take off the head check the pistons for excessive play... at this point you must know that you are into new rings and a hone or new pistons/ rings/bore job.Not to mention a new complete set of gaskets ( you'll find those O rings in there)pucks (sold seperately)and yes you might as well plan on lower seals while you are there, nobody wants to spend twice because the cheaped out in the first rebuilt and ran the risk that some of the 40 year old seals are like new. The primary chain stretches from use, really stretches when abused... will start to grind aluminum at the timing chain adjuster perch (you could check that by simply looking around when the pan is off.
My point: You still don't have a clue what's wrong with any of these engines, so why put any engine back in?
If you are going to take the whole frame down, sand blast/or other method to get the rust off, upgrade/or re-grease old steering bearings,repaint frame. Then there's time to spend cleaning and checking the wires,clean every part, buff or paint all the parts, change wheel bearings , brake shoes, master cylinder rebuild and caliper seal, fork rebuild and possibly swing arm bushings to replace.....riding time is over anyways....might as well go straight into engine rebuild and save yourself a headache next riding season....., besides you'll get everything covered in oil with those leaky Orings, probably have to get new clutch ,filter, oil, plugs, points and condensers, adjust the valves, adjust the timing chain and clean and sync the carbs.... and that's on an unknown engine that you want to use temporarily.
And all this stuff has nothing to do with if you want a cafe racer look or anything else. The cafe racer will require seat mod, hoop weld in , electric mods and a host of other modifications if it is to turn out to be anything worth looking at.
Or maybe we're just talking about a flat black rattle can paint job on a ratty running classic machine that certainly deserved better...and it does...and so do you.
This project , if to be done correctly and safely will require you to tighten up your game plan,examine each and every part for both safety and reliability if you are planning to ride it. If you're planning sell it completed examine everything you touch twice, if you just want to flip it....now is the time.
You are looking at a a$$load of work and dollars should you want to do this right. If you decide not to do it right , what is the point of it all? You tube? There's lots a dumba$$es on youtube doing things when they have no idea what they are doing. Don't be that. This forum and it's members can give you the information you need to both present well and informed with good information for your youtube vid ( for future viewers) and complete a machine that you can be proud of, and enjoy for years to come.
I would like you to be successful with this project and present well with accurate information for your future viewers. This is in no way meant to be harsh, don't take it that way....but...there will be people that will find you on youtube needing good information, and so far you don't have any and haven't asked the forum for any. please ask questions so you'll know what to expect before your next move and have the answers for your findings, so that you make the proper actions while filming ,you will be able teach others what you have learned in an informed, confident manner.
With respect, RB
