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How-To: Honda CB750 Top & Bottom Engine Rebuild 1969-1978

Link to buy full video

Okay so this video here on youtube is a sample the full rebuild video is nine hours long and can be purchased by clicking on the link in the upper right or in the video description this video covers the cb750 the single overhead cam 1969 to 1978 is covered the motor in the video is in 78 they’re all pretty similar and that’s kind of the generation that this video

Covers also included are some service manuals a parts list a tool list and as always email support is included okay so you can buy the top end only or the bottom end only or the full rebuild top end is four hours long bottom end is five hours long and like i said the full video is nine hours long it is freaking long okay let’s summarize what parts were replaced

And what’s included or what’s covered in this video okay so as you know i bought this project for 550 bucks i bought the whole bike and it’s a complete wreck the engine was seized it looked nasty corroded and dirty and obviously now it’s all brand new so let’s let’s talk about what parts were replaced let’s start up here the valve guides were worn the valves were

Pitted so this was sent off to cycle exchange they did a full valve job new valves new guides valve job the cylinder rings were rusted to the cylinder wall and the bores were all screwed up so i had to go to the next over bore size which is half a millimeter over okay so they did an awesome job with the machine works super fast turnaround i would highly recommend

Cycle exchange for any machine work that you need also what i bought from them is a full gasket set and i went with a multi-layer steel mls head gasket because as you know this engine needs to be pulled for the head to be retorque t’ or if you have to do the head gasket in general and you have to disassemble half the top end here to retorque the fasteners not

True with mls so that’s why i went with it i would highly recommend going that route if if you can okay so also a new cam chain new primary chains all new cam tensioners primary chain tensioner new rod bearings crank bearings i had to find a better used crank because my old one was pretty roughed up all new transmission bearings new clutch all new gasket seals

Let’s see what else am i missing here i had cycle x rebuild the primary chain wheel there’s little rubber bumpers in there cushions that they rebuilt for me everything was vapor blasted in my diy vapor blaster cycle exchange did blast these two parts but i touched them up with the vapor blaster afterwords to get a consistent finish all the bolts were either

Replaced or replated now 90% of the bolts can be ordered from the oem however for the other 10% what i did is i stripped the zinc and rust off in the vapor blaster and sent him out for replating and they turned out really nice so like i said this video is 9 hours long it’s the freakin longest video i have out there right now and it covers everything step by step

I take every transmission gear apart every clip every seal every bearing i show you how to replace freaking everything ok so here’s some random info for people that think videos like this should be free ok this took me six months to do both here in the garage and at the computer editing and as you know or may not know i have a full time job and i have four kids

So sometimes i’m out here 8 p.m. to 11 p.m. sometimes i’m out here at 4 a.m. to do a little bit of work before going to work all this footage the raw footage is 200 gigs 300 video clips that i had to put together for this 9 hours and that’s pretty much why it’s not free okay alright that’s it for this video enjoy the sample and leave a comment below ok the first

Thing we’re going to do is loosen all the tap it covers ok so it’s a 17 mil and make sure you’re using points socket because these things mar easily and they should come right off and i will say that usually these are all chewed up because people use the wrong tools and these are all in really good shape which is surprising okay they shouldn’t be crazy tight on

Here there’s no reason to tighten these up and there’s old rings on all of them okay next up all these phillips screws are a number three size and you’re gonna want to use jis screwdrivers because they fit the fastener better than a phillips these are japanese screws this here is a nice screwdriver it’s a vessel and pacta it has an impact driver built in and and

What that means is you hit it with a hammer and it twists the screw so the hammer impact keeps the bit in the screw and then it gets a little twisting action so we’re gonna see if this works sometimes it does not you need to bring out the heavy duty impact again this is a vessel number three jis so first let’s try this because this is a fifteen dollar screwdriver

And it’s not budging it sometimes it does not work okay try the bigger model it’s turning but man it is really frozen in there here that already got this one loose let’s try this one wow it’s crunchy okay here’s a little tip see how they’re all sticking out about a quarter-inch that tells me that it’s the correct length so i don’t really keep track of screws

And where they go i mean i might bag these and with a sharpie label it valve cover but i never pay attention where they go because they all should stick out the same and then you know they’re the correct length all right so here are these three and these screws are totally junk but we’ll go ahead and remove this cover yo ring might as well get these two screws

As well let’s get a different angle for these we’ll just start on one end and work our way all right some of these were really stubborn okay so i left them all in and you can see that they’re all sticking out about a quarter-inch okay so as you pull them out you know they might be different lengths but just remember you put them in so you got a couple

Short ones and long ones can’t really screw it up if you just use that tip and those are very corroded that i have to replace those okay see if we could give us a couple taps to break it loose there we go got our valve cover off now there’s two dowel pins ones are over here ones over here there’s a gasket and there’s a little gear here for the tack okay we’re

Gonna get this tech gear out of the way what i’m using here is a crappy screwdriver and there’s a little tab here that we need to bend over just like so and then use a 10 mil to move this so you remove the screw and then this locking tab and then we can pull this guy out and this guy is cracked so i’m gonna have to look for a new one okay now with the valve cover

Off we’re gonna remove the rocker arms and the shafts now in order to do that we need to make sure that all four of these are off the cam lobes so there’s no preload on the spring and that way we can slide the shafts out so i already rolled the motor over if you hear this that’s a little bit of play that’s your valve lash and that means it’s on the it’s off the

Cam eccentric it’s just on the base circle of the cam

Transcribed from video
How-To: Honda CB750 Top & Bottom Engine Rebuild 1969-1978 By How-To Motorcycle Repair