Topic: '77 CB750F Rebuild.. from parts, seized motor, no title

[maxrock]

Hey guys,

I am in the process of rebuilding a 1977 CB750F from a few boxes of parts, frame and locked up engine. Purchase price was $400 and $50 of gas. No title.

Progress made this far:
- Freed up the engine and disassembled it completely.
- Determined old head was cracked; purchased new head for $120
- Removed valves from old head; determined they need to be cleaned up as does new head surface + combustion chambers.
- Had new sleeve installed in #3 cylinder, cut and existing sleeves honed. $150 incl sleeve, labor and shipping
- Had crank and cam polished, $30
- Purchased engine rebuild kit for $80

So far I'm into this for $830. I still need a) new half shells, b) new bottom end bearings, and c) head/block resurfaced/checked with profilometer, d) chains + chain tensioner. Then I will seal her up and get on with buying more parts ...  Looking forward to fuel savings.......

[Tinman]

Looks like you and I are doing similar builds, I have two 750 F's , a 77 and a 78, one will donate parts to the other. Hopefully getting a title won't be too much trouble. Tinman

[bryanj]

Depends on the F model 77 might be F1 or F2, 78 will be F2 and a lot of motor parts do not interchange between F1 and F2

[Tracksnblades1]

Hey guys,

I am in the process of rebuilding a 1977 CB750F from a few boxes of parts, frame and locked up engine. Purchase price was $400 and $50 of gas. No title.

Progress made this far:
- Freed up the engine and disassembled it completely.
- Determined old head was cracked; purchased new head for $120
- Removed valves from old head; determined they need to be cleaned up as does new head surface + combustion chambers.
- Had new sleeve installed in #3 cylinder, cut and existing sleeves honed. $150 incl sleeve, labor and shipping
- Had crank and cam polished, $30
- Purchased engine rebuild kit for $80

So far I'm into this for $830. I still need a) new half shells, b) new bottom end bearings, and c) head/block resurfaced/checked with profilometer, d) chains + chain tensioner. Then I will seal her up and get on with buying more parts ...  Looking forward to fuel savings.......

Good Luck on your project…

Interesting you 410 cylinder head was cracked…

Do you know where it cracked?

I have 3) spare 410 F cylinder heads. Just wondering where I should be looking for the cracks. I’ve never really seen any post on cracked F2 heads.

Thanks in Advance..

[HondaMan]

While it's apart...
1. Check the wear on the valve guides. Almost all of them are worn out by 10k miles. Use bronze guides in place of the old cast-iron type for MUCH longer life.
2. If it is the F2/3 engine, I'd strongly suggest using the top valve spring retainers from CycleX. Ken's fix for the cheap stamped-steel ones Honda used are worth every single cent. They drop right in and will prevent the pull-thru of the valves in those stamped-steel ones Honda used (which are quite worn now).
3. What is the piston-to-bore clearance of the finished pistons and the freshly-bored one? If it is more than 0.0018" it will burn oil.