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restoring my 1982 cb750f

mikey1988

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hi all I bought my old mans 1982 cb750 off him last year as a project bike with the plans of doing a complete rebuild on it. I have ran into some problems when it comes to the engine. I have removed the rocker cyclinder head cam chain tensioner and the one bolt that holds the bore to the cranckcase but just cant get it to come free. I have tried everything from tapping it with the rubber mallet, soaking it in wd40 jacking it up with bolts, rotating the crank to try and lift it with the pistons but it just won't budge. the pistons are free and move up and down the bore so its not seized in that sense. has anyone got any ideas on how to get it off before I just split the crank and pull the pistons out backwards. many thanks michael
 
update I have removed the clutch, automatic timing unit, alternator and rotor, starter clutch and starter motor. undone the top crankcase bolts just getting ready to flip it over to undo the bottom bolts but don't now whether the oil filler needs to be removed for the crankcase to separate or not. I have checked the Haynes manual and the Honda workshop manual and it doesn't say it needs to be removed but it doesn't look like the crankcase can be split with this in place. any info would be greatly appreciated Michael
 
I dont quite understand your first post as to exactly what you have removed but it sounds like you do have the head off correct? If you have then it is probably stuck to the locating dowels. You can do some gentle prying in several areas around the block to work it loose. I dont remember but I am almost certain you will not be able to pull the pistons out the bottom. Every motorcycle motor that i have had apart does not have room to pull the pistons out the bottom as the main bearing saddles are normally closer together then the width of the pistons. That is why they make the cylinder removable. You will have to get the cylinder seperated anyway at some point so you might as well do it now...if you damage it you will just have to look for another one because if it is that stuck it wont be any easier with the cases split. As far as the oil filter no it doesnt need to be removed but if you are rebuilding the motor why would you leave it on? It will need to come off at some point anyway.
 
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