Topic: Engine rebuild?

[zekd]

How much money would it roughly cost to have a motor completely rebuilt on a cb750? Just curious because I don't think I will have the skill to rebuild an engine myself. Thoughts?

[calj737]

Pistons, rings, valves, guides, and springs? $1200 in parts. $600-$1500 in labor depending... That's what I would budget but it all depends upon what you have done, who does it, and the quality of parts used.

[MCRider]

Yeah. How fast do you want to go?   

If many of the hard parts are reusable, like pistons, valves and guides, cost will be less. You'll need rings, gaskets, and labor.

Trouble might be in finding smeone who knows the old CBs and wilil work on it.

IIRC, basic overhaul per Honda was 8-12 hours x shop rate.

PS: IIRC2; that's for a top end job. Couple of those hours is just getting it in and out of frame. OCICBW

[Davez134]

Why the rebuild? What's the problem? Bottom end too? I didn't think I had the "skill" to rebuild mine either. Have you read through the shop manual? If you've got some time and the right tools, it's worth a shot. Simple motors really if you take the time to check all clearances.

[Phinn]

It's really not that difficult.

There's one thing I noticed that isn't in the basic Shop Manual (or Clymer) -- when you have the case apart, and you're getting ready to seal it back up, there are two oil seals (out of seven) that MUST be installed BEFORE reassembling the case halves --

(1) the big oil seal that goes behind the front sprocket, and

(2) the oil seal that goes on the right end of the crankshaft (behind the ignition electronics).

The other 5 seals are installed after the case is reassembled --

(3) the one on the gear shifter shaft,

(4) the one inside the clutch housing where the lever attaches,

(5) the one for the kick starter shaft,

(6) the one on the inside of the big starter clutch gear behind the stator rotor, and

(7) the little one in the tachometer slot on top of the valve cover).

If you leave the first two out then seal up the case, you have to split it open again to install them. Ask me how I know.

Other than that, just take your time and follow the manual. Read the big thread on how to avoid oil leaks.

Get a good torque wrench. The case bolts that surround the crankshaft need to be torqued down very carefully.

[Jerry Rxman Griffin aka MuthaF'er]

Why would it cost anything? What's the problem(s)? May not need it?? May just need honing and re-ringing but only if it's burning oil??

I spent $7000+ on mine but that's doing it to the hilt with some serious speed stuff. How deep are yer pockets?

Just depends 

[HondaMan]

I rebuild several every year. The stock ones range between $1500-$2500 for K0-K6 engines, or about $500 more for the post-1975 types, big bore jobs can add $1000 to that figure.

[70CB750]

It's really not that difficult.

There's one thing I noticed that isn't in the basic Shop Manual (or Clymer) -- when you have the case apart, and you're getting ready to seal it back up, there are two oil seals (out of seven) that MUST be installed BEFORE reassembling the case halves --

(1) the big oil seal that goes behind the front sprocket, and

Why would that be?  That seal can be taken out and installed with engine in the frame.

[lrutt]

And define re-build.

Just rings?
Rings and valve freshen up?
Bore, piston, rings, guides, valves?
Bore, pistons, rings, guides, valves, main and rod bearings?
Bore, pistons, rings, guides, valves, main and rod bearings, trans bearings?

Way to many variables to provide you an estimate.

And as others have said, what's the problem? It boggles my mind to see people time and time again on this forum, buy a bike and are going to cafe or bob it and the first thing they do is tear everything the hell apart without knowing what it really needs.

so please, let's do a Paul Harvey and hear the 'Rest of the Story'.   for those of you old enough to remember that.

[ekpent]

Quote Paul Harvey--"Good Day"-   Guess I am old enough   

[Wobbly]

Depending on the model, a NOS cam shaft with holders alone can set you back about $ 1500 or more just for parts--unless you can travel in time. So, one might as well ask how much it costs to buy a car. The answer is the same: it depends.