Topic: My First Motorcycle: 1976 CB750F

[ZingZing]

Technically, I should've made this post earlier but I was honestly having a lot of fun digging into this project.

A couple of weeks ago I finally finished my degree and as a present to myself, I picked up my brand new (to me ) 1976 Honda CB750F in Candy Antares Red. I drive my dad's RE Hunter 350, which is a small and fun bike but honestly, 20 horses ain't cutting it anymore and feels less than safe at highway speeds. I wanted a project that would be simple, not overly expensive, and most importantly worthwhile, hence the SOHC CB750 platform. Also so I can have my own motorcycle.

The story goes that the dude I bought it from "found" the bike on a property he had recently purchased and just wanted to get rid of it. No title, no keys, and no history whatsoever but it has a plate on from '98 so it's most likely been sitting since then and definitely looked the part...sort of.

Lots of rust and the seat was shredded but it wasn't missing any parts, engine wasn't seized, and all the electronics worked. However, I didn't try to start it or do a compression test cause I planned to do a full rebuild anyways. Also the bike has 40,000+ miles with no real history so I needed to do a full rebuild for my sanity. Sorry for not grabbing more pictures of when I picked it up or "the before". I have pictures of all the parts but that's the only photo I have of the bike put together.

At this point I've completely taken the bike apart and it felt like a good point to make this post before I start inspection. Basically I love this bike and I haven't even driven it yet. I've never taken apart a vehicle to this extent but it was so simple and everything just made sense, plus with all the support this bike has it's pretty hard to get lost.

I'll be honest the mouse skeleton that was guarding the fuse box was a bit of a turn off but nothing a garden hose couldn't fix. Dealing with the JIS screws also sucked cause I couldn't remove the breather cover on the head so I had to remove an exhaust stud to drop the motor instead(just one ). The brakes were seized and the rear caliper wouldn't come apart so I had to drop the whole rear wheel so I could smack the caliper off the rotor. Then yesterday, I snapped the very last lower case bolt sending me into a deep depression till reddit informed me that both cases aren't threaded so I could still split the cases. Which I did .

For now the main plan is to get the bike back in working order with an emphasis on reliability, not looks for now. Unfortunately, I too quite dig the cafe racer look that many of you hate and eventually that will happen with this bike but NO FRAME MODIFICATIONS, i promise. Soon I will send the frame and some brackets to get sandblasted and powder coated black but everything else is just gonna require a lot of elbow grease. I'm also going to get rid of all the chrome as most of it is rusted too heavily to restore and rechroming is not in the budget at this time but black paint is. The tank is going to get painted with a bunch of spray paint cans but properly with epoxy primer and 2k clear and most likely in either Porsche Malvern Red or Ferrari Rosso Fiorano. New steering head bearings, swing arm bushings, lower shock bushings, sprockets, chain, all transmission bearings, all gaskets, all o-rings, exhaust studs, probably more I'm missing. Then I gotta do the engine inspection and figure out what else I need (or don't ).

That's kinda everything that's planned for now and I would love to hear any and all questions, comments, or concerns.

Also I don't know who's going to see this but if you're thinking about jumping into the SOHC CB750 platform then frickin leap cause you (probably) won't regret it. And get yourself Hondaman's book and the $20 craftsman impact screwdriver cause it worked flawlessly and the PH3 bit you get with it I think is designed to work with JIS fasteners.

[newday777]

Welcome aboard the forum ZingZing from southern NH.
A worthy challenge that you took up. I hope you took lots of pictures before you pulled it apart to see how the puzzle goes back together! Good wrenching to you. Ask if you need to know something specific.

[newday777]

Have you watched the hackaweek series on YouTube of the 750 rebuild?

[Jerry Rxman Griffin aka MuthaF'er]

Looks like your engine has either been swapped out or gotten into with a replacement head installed. What's the serial number?

Good luck with your efforts and saving another fine F

[ZingZing]

Appreciate the welcome newday, thanks for having me .

Have you watched the hackaweek series on YouTube of the 750 rebuild?

I just took a look and seems like a sweet channel that'll help me out. I've been watching Spanner Rash, Mike Barker, and Brick House Builds on YouTube who were also real helpful.

The parts I'm stuck on right now is removing the lower shock bushings, swing arm bushings, and front axle. My blind bearing puller keeps slipping out of the bushing and I'm worried about warping the swingarm from using a propane torch too much.

The swing arm bushings suck cause the pivot shaft is stuck and won't come out with no amount of hammering. Although maybe I could hit it "better", at the moment Im just standing on one side of the swing arm while I hit it.

There's also the front axle which I have tried using a breaker bar and an impact drill on but no movement. I've only got a 12v impact if that matters. Originally I tried using a 5/16 threaded rod to hold the one side of the axle but that didn't go too well.

I used a proper punch later which at least didn't bend but still didn't get the axle nut off. I've tried soaking everything in pb blaster and I have smacked everything a bunch everywhere to try and shock everything but still nothing. Any advice to get these bastards off?

[ZingZing]

Looks like your engine has either been swapped out or gotten into with a replacement head installed. What's the serial number?

Good luck with your efforts and saving another fine F

Thanks Jerry, another fine F indeed. Love the super sports.

There's the sn. Am I right with saying that the engine and frame don't match (unless super lucky). And what makes you say that it is a replacement head?

[Jerry Rxman Griffin aka MuthaF'er]

That IS a F1 engine serial number. I may have misspoke about the head. Look for "392" on the top fin intake side between 2 and 3. The shape of the combustion chamber in a F/F1 392 head is different. Smoother. Probably contributes to the alledged 0.2 bump in CR along with the full piston crowns. Hard to describe but easy if you have an earlier head to compare. 

Your swing arm bushing is an early replacement. I also used those. The original was a "plastic" compound piece. I have a new set of those if you need but you are probably better off in the long run with the bronze inserts like you have. Just measure the clearance between the bushing and the pivot.

Maybe clean up the swing arm then bake it in the oven. I have never removed the lower shock bushings.

My parts cave has MANY F parts if you find you need something but you can't have my spare 7000 mile engine  . 

The engine serial number never matches the frame

[ZingZing]

Look for "392" on the top fin intake side between 2 and 3. 

I distinctly remember thinking about scat packs at some point during teardown so I’m pretty sure there was a 392 somewhere.

The issue with my swing arm is that the pivot shaft is not coming out. I took the two retainer caps off and on videos I saw the shaft just falls out with ease then the bushing are hit out with a punch. My shaft (ha) isn’t moving at all, however I haven’t tried heat yet. Not too sure but the zerk was covered in grime so I'm sure it wasn’t greased for a long time before it sat.

I’m waiting for my grease gun to come in the mail and I’ll try to see if I can get any grease in to loosen up the pivot shaft.

[Jerry Rxman Griffin aka MuthaF'er]

Taking a second look and comparing the swing arm bushings to mine I see it looks like you still have the original phenolic/bakelite/etc bushes with the pivot shaft still in place. Dark plastic. It should have a shoulder under all the grease/grime. The pivot shaft is not an easy part to locate so hopefully it is good on the bushing ends. Brass wire wheel to clean it up just don't sand unless you have to. It only contacts maybe an inch or so on of each bushing. The middle really doesn't matter. Does it even pivot? I know you will want to replace the bushings with bronze shouldered ones. Can be found cheaply. You can always cut a shoulder off a bushing and take a BFH and a 3/8" socket etc and drive it out the other side taking the other bushing with it. . Try that before you fill it with grease and make a big mess when it does finally come out.

Scat packs?? What do you mean?

[ZingZing]

Does it even pivot? I know you will want to replace the bushings with bronze shouldered ones. Can be found cheaply. You can always cut a shoulder off a bushing and take a BFH and a 3/8" socket etc and drive it out the other side taking the other bushing with it.

Scat packs?? What do you mean?

Yeah I would love to avoid any and all messes if possible so I'll give that a try. It does not pivot.

Dodge Challengers and Chargers with the 6.4 hemi (392 ci) are the "Scat Pack" models so nowadays 392 is basically a synonym for scat pack. Just a dumb way my brain works.

[ZingZing]

Got the axle spacer nut thingy off the front wheel after I used a crack in my garage as a vice to hold my punch while I got a breaker bar on the other end.

The swingarm, however, never gave up till the end. I went to a local motorcycle shop and they were able to get the shock bushings and the collar/bushings out but had to cut the collar out in the process which honestly really blows.

However, they did end up marring the swingarm itself in the process.

How bad is it? Will the deep grooves affect how sealed the system is? I would think the dust cap at the end would solve that but the face on that end is not completely flat. I tried to take pictures of the angles I thought showed it the best.

Hondaman emphasizes that the swingarm pivot is one of the most important moving parts on the cb750 so I want to make sure I do this right. Do you guys think I can install new bushings and get a new collar without having to resurface that end? And what's the best way to clean the inside of the swingarm tube? I was thinking power drill + extension + small brass wire wheel and try to do it in like a cylinder honing fashion.

Also what other swingarm collar part numbers interchange with the '76 CB750F swingarm? If I recall correctly, not every swingarm collar is interchangeable and the F collars are really hard to find.

[ZingZing]

Took an actual close look in the tank and I'm confused.

Is my tank rusty? (obviously the outside is sparkling )

Now that I look closely it doesn't look like rust, maybe some kind of liner cause at the top bar you can see the marks where it rubber off from the hanging thing. I've gotta clean it but I think I don't need to de-rust my tank! (hopefully) The seams from what I can see look good, except from something in the back right of the tank but it kind of looks like its a part of tank (slightly shown in the last photo of the above 4).

Please tell me I don't have to de-rust my tank it would just be a much welcomed victory right about now. The downside is if it actually is rust and I look like a dumb-a that would kinda blow but not as much as pumping rust into the carbs. Also, is the lockable cover black in color (rhyme) on the F's?

[Jerry Rxman Griffin aka MuthaF'er]

Looks like #$%* on the outside haha but that can be taken care of with paint. Try to find a replacement tank in decent shape!! Somewhat unobtainium. I can't tell from your pictures but perhaps just surface flash rusting? Flush it out with some vinegar then dry it. Fingers crossed. That would be considered a good F tank if the inside is good. 

[Jerry Rxman Griffin aka MuthaF'er]

The swingarm should be fine as long as the collar rotates properly. That part number is 52141-390-000. I'm not sure which bike is a -390 but it isn't a 75/76 750F so there are better odds to find a new one. Just use some sort of round brush with solvent to clean the inside. Your idea of honing fashion is good. The important parts are the ends where the bushings go but the interior should be as clean as possible. 

[ZingZing]

t

Looks like #$%* on the outside haha but that can be taken care of with paint. Try to find a replacement tank in decent shape!! Somewhat unobtainium. I can't tell from your pictures but perhaps just surface flash rusting? Flush it out with some vinegar then dry it. Fingers crossed. That would be considered a good F tank if the inside is good.

I think the inside will clean out nicely with vinegar but the outside is just depressing. For now I'm going to try and sand and primer it all nice to prevent any future rust then finish it with my best at home paint job. Then down the road I'll get it restored to the OG Candy Antares Red. If I can pick up a tank for cheap there's also that.

You're the man Jerry! Appreciate all the insight and I'm relieved the swingarm will be a ok.

[HondaMan]

I can fully rebuild the swingarm if you give up on it(?). I make bronze bushings to fit each arm, as many of them are distorted nowadays, sometimes such that the arm itself must be bored round again before a bushing can be made to fit at all. Then the bushings get bored to match the collars I also have made, just for this system. Many off-the-shelf bronze bushings don't fit (in various ways) and/or are not properly toleranced: the clearance collar-to-bushing is 0.0008"-0.0012". Keep in mind, this clearance multiplies by the length of the swingarm between the pivot's center and the rear axle's center, and that number by x2 because both sides of the collar have clearance. The rear wheel should not wiggle side-to-side at the axle by more than 0.2mm when new parts are used: 0.0mm is better.

[Jerry Rxman Griffin aka MuthaF'er]

There you go. Hondaman to the rescue.

"If I can pick up a tank for cheap". Not likely to happen either for cheap or a good tank. Work with what you have if fairly decent. I sit on some pieces but I am reluctant to cut loose for that very reason. At least for now anyway. Tank, pivot arm, swingarm, etc. Along the way let me know what you need. Perhaps I can help......

[ZingZing]

"If I can pick up a tank for cheap".l

Probably should have said if I can find one for a good deal based on condition. Right now I don’t really need anything except a collar and a couple electrical connectors I had to break during disassembly. Jerry, I’m imagining you as a dragon sitting with his pile of gold but it’s all 750F tanks.

I can fully rebuild the swingarm if you give up on it(?). The rear wheel should not wiggle side-to-side at the axle by more than 0.2mm when new parts are used: 0.0mm is better.

Thanks Hondaman. Another question I have was just about converting the F collar to the earlier ones. There’s a guy near me selling a an early collar with the fat grooves and a matching pivot bolt with the zerks. I just swap the collar and pivot bolt and don’t use the normal middle zerk anymore? Seems simple and if I need a new collar might as well upgrade to the reliable system.

And how do I go about getting bushings made or modified? I don’t have a mill or a lathe, so just provide dimensions and material to machine shop? How much should it cost typically to have a set of two bushings made and is there a difference in the machine shop procedures depending on whether I choose to use 660 or 841 bronze? I’ve only had a machine shop cut holes in sheet metal once before.

Also I’m not giving up on the swing arm, and I really would love for you to rebuild it but alas that will be one of those later things when I’ve got the money to do a full resto. For now she’s just gonna be a reliable daily driver.

[Jerry Rxman Griffin aka MuthaF'er]

https://www.vintageconnections.com/  Do yourself a favor and get the crimping tool also!

I did find a spare collar and fresh silver metallic powder coated swingarm with bronze bushings. PM me.

[HondaMan]

"If I can pick up a tank for cheap".l

Probably should have said if I can find one for a good deal based on condition. Right now I don’t really need anything except a collar and a couple electrical connectors I had to break during disassembly. Jerry, I’m imagining you as a dragon sitting with his pile of gold but it’s all 750F tanks.

I can fully rebuild the swingarm if you give up on it(?). The rear wheel should not wiggle side-to-side at the axle by more than 0.2mm when new parts are used: 0.0mm is better.

Thanks Hondaman. Another question I have was just about converting the F collar to the earlier ones. There’s a guy near me selling a an early collar with the fat grooves and a matching pivot bolt with the zerks. I just swap the collar and pivot bolt and don’t use the normal middle zerk anymore? Seems simple and if I need a new collar might as well upgrade to the reliable system.

And how do I go about getting bushings made or modified? I don’t have a mill or a lathe, so just provide dimensions and material to machine shop? How much should it cost typically to have a set of two bushings made and is there a difference in the machine shop procedures depending on whether I choose to use 660 or 841 bronze? I’ve only had a machine shop cut holes in sheet metal once before.

Also I’m not giving up on the swing arm, and I really would love for you to rebuild it but alas that will be one of those later things when I’ve got the money to do a full resto. For now she’s just gonna be a reliable daily driver.

There's some subtle differences between the -300- series collars and the later ones: the later ones have 2 different OD sizes on those outer bearing surfaces, which is: the outer ones are 0.0004" larger than the inner portions (the groove divides them). This was Honda's [lame] attempt to let the grease from the center zerk squeegee out toward the outer ends of the pivot.

Didn't work, though - that;s why the inner halves were jammed with rust and made it so hard to disassemble.

If you can find some NOS parts, use the later collar with the Honda-supplied (but crummy) injection-molded MIMs-metal bushings (hard to install) to get the correct clearances. If you use the early collar with those grease grooves and Honda's MIMs-metal bushings there will be too much clearance, letting the rear wheel wiggle up to 3mm upon install. That's enough to make the bike feel real unfriendly.

[Honda Hansel]

Hi
Sure looks like a project
bit of advice for the electrical
Get a new harness. It's cheap for a Honda..well spend cash on the project
I don't do a job with out replacing the harness $$$$100 well spend (US $$$$70)
There is lot's of Honda parts out there for not much money
I been getting a lot of parts from VintageCB750.com here in Canada
They have most of the parts needed to do a restoration
Also got a lot of parts from CMSNL.com got a lot of hard to find parts

Honda Hansel
 
   

[ZingZing]

Get a new harness.
   

I was planning on keeping the original. Why do you recommend getting a new one?
All the lights worked and only one connector had corrosion on a couple pins. I did end up breaking 2 connectors while disassembling so I would have to replace those.

[HondaMan]

You can get the connectors (and an excellent crimper for them) from VintageConnections.com. I use a lot of them.

[ZingZing]

Never really done this before so I’m not 100% sure but I think I need a new camshaft.

https://imgur.com/a/UbF7WH2

Based off of the journal-bearing clearance from 3 alone, I’m screwed. There also seems to be a some pitting on some of the lobes that I can feel with my finger so doubly screwed.

Any advice or opinions, just don’t kick me in the nuts.

Also I’m using telescoping gauges for bore and I keep getting different values. I measured many times and in the end I just wrote down the worst numbers cause I don’t trust my measuring skills.

[69cb750]

Based off of the journal-bearing clearance from 3 alone, I’m screwed. There also seems to be a some pitting on some of the lobes that I can feel with my finger so doubly screwed.

Looks like oil starvation.
There are some oil jets in the head with very small holes that can be blocked by silicone and dirty oil then this happens.
Lots of CB750 engine parts on ebay.