Topic: Motor rebuilt by someone else

[lightsareout]

I recently picked up a CB550 74 frame/motor that also came with another 75 motor.  The 74 motor is leaking oil in many areas and would need a full rebuild before I would invest my time putting it into my build.  The 75 motor looks to have been rebuilt recently but the previous owner did not have any background on it.  What testing and investigation can I do on this motor before proceeding with it on the bike?  I think it was recently rebuilt due to the liquid gasket along the seams and no oil in it.  I was going to check the compression on it but not sure what else to check to decide if I'm good to go or should crack it all open.

Thanks for any advice!

[MoMo]

You can do a leak down test.  Hope the liquid gasket you''re referring to isn't silicone...Larry

[lightsareout]

You can do a leak down test.  Hope the liquid gasket you''re referring to isn't silicone...Larry

its grey, isn't hondabond white?

[chewbacca5000]

Liquid gasket is not a good sign.  Favorite tool for hack jobs.  I would do a compression check on both motors and pick the one with the best compression.  Then replace the gaskets on that one.

[lightsareout]

i should clarify the grey sealer is oozing out between the crankcase halves and around the oil seals, I don't see any on the top half.

[thirsty 1]

Remove the plugs and install a oil psi gauge. Spin it over with the starter. You should get around 20-30 psi. Check comp with and without oil in the cylinders. Check the valve timing before doing anything. Set the ignition timing ie: points. Check the valve clearances

[MoMo]

i should clarify the grey sealer is oozing out between the crankcase halves and around the oil seals, I don't see any on the top half.

good to hear.  Gasgacinch is grey, that should not create a problem on the lower end.  I  once bought a 750 on which the lower end had been "rebuilt". less than two miles the lower crankcase started to break.  As mentioned earlier leak down will give the most accurate condition of the top end...Larry

[lightsareout]

Remove the plugs and install a oil psi gauge. Spin it over with the starter. You should get around 20-30 psi. Check comp with and without oil in the cylinders. Check the valve timing before doing anything. Set the ignition timing ie: points. Check the valve clearances

thank you for the tips!

[BomberMann650]

Hondabond/permatex are both grey.

Used perma grey on my clutch cover.  Seems to have done the job.  350 miles and holding.

[thirsty 1]

Remove the plugs and install a oil psi gauge. Spin it over with the starter. You should get around 20-30 psi. Check comp with and without oil in the cylinders. Check the valve timing before doing anything. Set the ignition timing ie: points. Check the valve clearances

thank you for the tips!

one more. Make sure it actually has an oil filter installed.