1980 CB750 “Beavertail” Cafe Build

[BeantownBeaverTail666]

Just gotta say.........Wrap? Wrap screams NEWBIE.

Thank you for the feedback! Funny how something like exhaust wrap can become so contested over time. Like I said in the thread, I'm not totally psyched about the results but I wanted to give it a go. We'll see where things end up. As for the engine cleaning - thanks for letting me know about it being painted. I was not aware of that. Diesel or Mineral Spirits are a great start. More to come!

 

[BeantownBeaverTail666]

We all start somewhere.
I hope he pulls it off.

Dunno how many I’ve seen get halfway thru and then just disappear.
Read the thread, everything, even his work place is new.

Go for it beantown!

I've seen a lot of dead build thread in my day - I don't plan to let my first build go unfinished! I have a schedule built out that hopefully stays manageable and steers clear of getting overwhelming or unachievable. But of course, if you'd like to bet against the house, good luck! Thanks for the interest.

 

[jasonscb750build]

I just picked up an 82 CB750f and ill definitely be following this build. I cannot express how much i appreciate people who make the effort to do build threads. I'm a very meticulous person when it comes to building anything out, but have such a hard time focusing already, that balancing a build thread on top of whatever it is i have going on feels impossible. anyways, im new to the forum and it only took about 5 minutes to find this thread. cheers man. looking forward to watching this form and using it to learn my bike.

 

[BeantownBeaverTail666]

I just picked up an 82 CB750f and ill definitely be following this build. I cannot express how much i appreciate people who make the effort to do build threads. I'm a very meticulous person when it comes to building anything out, but have such a hard time focusing already, that balancing a build thread on top of whatever it is i have going on feels impossible. anyways, im new to the forum and it only took about 5 minutes to find this thread. cheers man. looking forward to watching this form and using it to learn my bike.

Congratulations on the bike! More than happy to answer questions or show you what articles/youtube vids helped me. I have been really enjoying writing out this build thread so I am happy you appreciate it. I'm hoping it will have some answers for others and will allow me to go back and relive the build once it's complete.

 

[BeantownBeaverTail666]

Week 4.5 Engine prep and Wheel Paint

Projects for the week
Engine Clean Degrease (this sucks!)
New Tires
Wheel Bearings
Wheel Sanding
Wheel Painting
New Sprocket
Rotor Deglaze
Rotor Paint

I’m attempting to tackle this build within specific sections/categories. Since I recently was in the brakes/suspension world I figured it made sense to continue to work on that part of the bike. This week I was able to give the wheels some love. I knew that with the wheels I wanted to paint them and it looks like the best process for that is to make the painting process be the last step for the wheels. Aka don't paint the wheels and then scratch them up while putting new tires on…

I put new wheel bearings in both wheels - I don’t know if the old ones were bad or not but I’m constantly in the “while you’re in there” mentality so I just went ahead and did them. It was fairly simple and the Clymer laid out some good steps. Hopefully they are straight and safe After the wheel bearings were done the wheels were off to a local shop to have tires mounted - I had no desire to try and muscle these on myself and also didn’t feel like looking into how/if that’s possible.

Onto the sanding and painting - these wheels might be the most frustrating things ever to sand. My knuckles and fingertips were in shambles after trying to rough these up and get 40 years of road grit off. The spokes are also kind of sharp on the edges so while sanding you’ll probably punch them a few times by accident. In the end, I was pretty psyched with the outcome. Maybe next year I’ll find a way to do some cool setup with wire wheels, but these will do for now.

Not pictured but completed

• New rear sprocket. The old one was going to look terrible against the newly painted wheels. I considered changing up the gearing on front and rear sprockets but I kept it stock for now. The CB750f gearing seemed to be sporty enough.
• Deglaze the rotors. I had no idea motorcycle rotors could not be resurfaced because they are too thin. I’m too used to the car world!
• Sand/Paint rotors. Hopefully deglazing these and repainting them is good enough for now because new rotors for this bike seem to be ridiculously expensive.

I started to degrease and clean the engine so it was more enjoyable to work with/take apart. I enjoy the part of all service manuals that say something along the lines of “the first priority when undertaking maintenance or repair work of any sort is to have a clean, dry, well-lit working area. Work carried out in peace and quiet in a well ordered atmosphere of a good workshop will give more satisfaction and much better results than can be achieved in poor working conditions.” Gotta have a clean space and clean parts to do a good job. The rear section of the engine by the sprocket was very dirty - it’s getting much better with some degreaser and scrubbing.

The engine is looking pretty good and ready to be torn into! Can’t wait to get in there and see what’s going on.

Grease removal:

Fieldnotes:
Com-stars are a pain to clean/sand/paint
Warmer weather will make painting more accessible
Use a small file to help painters tape come off in tricky places
Using Kerosene as a degreaser is sketchy when done in your basement! Purple Power will have to do
Tracking grease into your house and on the carpet is not recommended

Upcoming:
Engine work begins!
Oil pan check
Spark plug/cylinder check
Cams out

 

[BeantownBeaverTail666]

Week 5 Engine Work Begins!

Projects for the week
Oil pan check
Valve Cover Off
Spark Plug Check
Cams Out

Hardest part of the engine work so far was trying to find someone to help me get it up on the workbench. All my friends that are in town were unavailable and the wife and I couldn’t get it done (though it was hilarious to try). I spotted my neighbor smoking a cigarette outside and he was my next victim to help out . After it was up on the table I wasn’t sure how to support it. I know in the automotive world the oil pan is pretty weak but on a motorcycle it looks to be pretty solid - just don’t want to break any fins. You’ll see in the photos below as I work on the motor I have a few variations as to how I stabilize it for work. I’m jealous of the SOHC guys who have engine holders available to them online. Another good reason for me to learn how to weld…eventually

First part of the engine I wanted to check was the oil pan. Thankfully there were no metal shavings in the oil - just a bunch of sludge (as expected on an older engine that sat for awhile). Since I plan to rebuild the engine I would like to run a magnetic drain plug just in case theres some self-tolerancing that occurs post-build. Hopefully not much of course.

After the pan was off I noticed that the bottom of the engine was pretty flat without the pan so I put some 2x4s (as pictured) below the engine to keep it straight up and down and easy to work on. I figured it would be a little disorienting to work on the engine with a slight tilt to it all the time…we’ll see.

Since I’m rebuilding the top end I don’t think the spark plugs will tell me much as they’ll be replaced in the end along with seals/rings/etc. All plugs looked pretty good with the exception of cylinder 4 (they’re laid out in order 1,2,3,4 in the below pics). I took a picture to document just in case anyways…

My end goal is to paint the engine black and have new stainless steel hardware. I can’t deal with the JIS screws. I know some people swear by them but it’s just asking for the bolt to be stripped and ruined in my opinion. Especially the old rusty ones.

The clymer says the first step is to line up the crank with the T markings so I had to document this as well just in case I forgot later on if I did it or not. We’re on our way to rebuilding an engine - this felt like the moment of no return.

While working on the engine and performing the above checks, the workbench quickly got pretty oily. I was at Home Depot and thought it might be a good idea to grab some toolbox drawer liner so I can use it as a spot to remove and inspect engine parts before putting them on the now dirty/oily workbench. Turned out to be a pretty helpful idea and pretty cheap.

While working on the engine I had to take a step back and admire my workshop setup. Just a little over a month ago this was a dirty/dusty/dim basement with no real purpose. Now it feels fully transformed into a nice amateur workshop for me to get this project done. Not bad progress in about 5 weeks time! I plan to bag and tag all components and place them in chronological order for reassembly - aka the last thing taken out of the engine will be right next to the engine while the valve cover will be further away as it’s the last to go on at the completion of the build. I even have some bags labeled with the page/chapter number with the instructions where they were taken out….I think I’m being a bit too detailed here.

I got both cams out of the engine with little issue. I moved painfully slow because I do not want to break any hardware or potentially ding the cams etc. I stuffed some rags in the middle of the engine so I do not drop and hardware into the case but it is still pretty nerve racking to have, what feels like, an open wound ready for debris to fall into. With that said, please excuse my wrench that is being used as a cam chain holder while I disassemble. I promise it is being used gently! I didn’t have any properly sized wood pieces or anything sturdy enough to hold up the cam chain to keep it from falling in the case.

Fieldnotes:
Engine is still dirty even after a good cleaning
Engine is pretty stable on the bench but torquing bolts might cause it to shift and be an issue
Drawer liner on workbench was genius
Engine components bagged and tagged and placed in chronological order

Upcoming:
Valve Head Off
Cylinder Jugs Off

 

[jasonscb750build]

fuck yeah man. the attention to detail here is second to none.

 

[jasonscb750build]

I think im going on week two now of having my bike, and over the course of these two weeks, I've managed to obsess about as much as possible over what I plan on doing with it, and oddly enough, the things that I'm heavily researching and beginning to decide on, is aligning somewhat with your build. All that being said, it'll be fun to see how linear our installs will be. I'm crossing my fingers that you get the the m-unit before i do.

As of right now, my bike runs and is completely put together, but I can't ride it because I don't know how to ride a motorcycle. lol. I kinda did things a little backwards and bought the bike first. My riding course is going to be mid April, so I've got a few weeks to completely fuck up a perfectly good bike with aftermarket mods and parts. The only thing that sucks is I live in Downtown Denver, in a studio apartment, and the only place i have to work on my bike is right where the designated motorcycle parking is in our underground parking garage. I plan on getting a cover and trying to keep things as tidy and inconspicuous as possible.

Glad to see you still going on this man. I'll be keeping up with ya. maybe just messaging might be better. I'd hate to clog the flow of your thread.

-Jason

 

[BeantownBeaverTail666]

I think im going on week two now of having my bike, and over the course of these two weeks, I've managed to obsess about as much as possible over what I plan on doing with it, and oddly enough, the things that I'm heavily researching and beginning to decide on, is aligning somewhat with your build. All that being said, it'll be fun to see how linear our installs will be. I'm crossing my fingers that you get the the m-unit before i do.

As of right now, my bike runs and is completely put together, but I can't ride it because I don't know how to ride a motorcycle. lol. I kinda did things a little backwards and bought the bike first. My riding course is going to be mid April, so I've got a few weeks to completely fuck up a perfectly good bike with aftermarket mods and parts. The only thing that sucks is I live in Downtown Denver, in a studio apartment, and the only place i have to work on my bike is right where the designated motorcycle parking is in our underground parking garage. I plan on getting a cover and trying to keep things as tidy and inconspicuous as possible.

Glad to see you still going on this man. I'll be keeping up with ya. maybe just messaging might be better. I'd hate to clog the flow of your thread.

-Jason

Hell yeah man thanks for the interest and kind words! Sounds like we are alike in the fact that we research/read/learn/watch...rewatch everything possible. YouTube is a great spot to learn as I'm sure you've seen. Honda's and cafe racers/brat builds are pretty common it seems so theres no surprise that we're following similar paths. I've already begun messing with the m-unit a bit and trying to whiteboard out my wiring diagram one circuit at a time. It's kind of a fun brain bender to work on. If I'm successful I'm happy to give you any pointers I learn along the way.

I appreciate the studio apartment life plus working on a motorcycle - it's a lot tougher to get motivated to work out in the elements and I'm sure in CO theres plenty of weather to think about. What are your general plans with your bike? Any maintenance? Paint/body work on the tank or frame? Show bike or commuter or both? So many questions lol

 

[BeantownBeaverTail666]

Week 6 & 7 Engine and Tank Work

Projects for the week
Valve Head Off
Cylinder Jugs Off
Tank primer/sand
Triple tree assembly
Frame mockup

Sorry for the lack of updates lately - I went to see a big hole in the ground…it was awesome. I’m going to combine the last two weeks of progress into one post to catch up. I feel like I’ve been working around the clock but still not making enough progress. Time to mock up the bike with some of the parts I’ve finished already to help boost morale.

I was able to get the valve head off as well as the cylinder jugs. Valves gave me no problem but the cylinder jugs were such a pain. Also after cleaning the engine for so long - there was still loads of road dirt deep down in all the cracks. As soon as the jugs came out all the dirt fell into the case. If I had only planned to do a top end rebuild I would be in a lot of trouble with all that dirt in the case. Luckily the case will be split this weekend!

This photo shows all the road grit that fell into the case after pulling the jugs off

And here is a photo of a lowrider mockup of the bike just for fun lol.

Time to take a break from the stress of the engine work and move over to sanding, priming and bondo’ing the tank. This process feels a little less risky as every bolt I turn on the engine I’m waiting for it to break or something else catastrophic to happen.

You can see the tank has some minor dents and it looks like the previous owner may have started to sand it down a bit because it’s a bit scratched up.

Here she is after primer! A good base layer to use as a guide while sanding. I’ll probably sand nearly all of this primer off.

And like I said…here is the tank post sanding with little primer leftover. I’ll probably prime this again and then bondo it up and repeat at least 100 times.

And finally, I attempted to assemble the triple tree but it looks like my buddy bought a part for a 550 and the forks cant get up and through to be in-line. I have a replacement on order and it should be here within a few weeks or less hopefully.

Another mockup pic again for fun with front forks!

Fieldnotes:
If doing a top-end rebuild - cylinder jugs are very hard to get off without debris going in case
Tank pinstriping is impossible to get off for some reason
Time to finally decide on a tank color..

Upcoming:
Split Case
Need new rotor
Sending engine out locally for Gloss Black Cerakote

 

[BeantownBeaverTail666]

Week 8 & 9 Case Split - Body work - Wiring Begins!

Projects for the week
Split Case
Sending out locally for Black Cerakote
Prime
Sand bondo sand bondo sand bondo…
Prime - just about ready for paint
Wiring Diagram started

Sorry for the inconsistency in updates lately. I found that it’s difficult to learn/document/do the actual work/report findings all in an organized way. Hopefully everyone is still interested - this is a ton of work!

The case split somewhat easily and it looked great inside. Not much to report on that front - I did not get too many photos of the process and I was extremely overwhelmed.

Now that the full engine has been sent out to get gloss black cerakote I can work on a few other projects with the freed up workshop space. Bondo/primer on the tank is the main focus and I will be trying my hand at building a wiring diagram as well for the M-unit.

Here are some pics of the tank as it stands currently. Not much to report here aside from bondo/sand/prime repeat. I think I applied my bondo too thick a few times because it cracked when it dried, which was extremely frustrating. Nothing better than bondoing your cracked bondo! If anyone has seen this cracking before I’d like to hear more.

And on to the wiring diagram…somehow my most dreaded part of this project is turning out to be the most fun and interesting to me. Wiring diagrams always used to be confusing to me until I took some time to learn about all the components and then tried my hand at building one. I am using the white board to test my skills at wiring the bike without needing to cut any wires just yet (it’s also too early for any actual wiring but I want to stay prepared). This is not the final version of my wiring diagram - so if things look out of place dont worry.

Fieldnotes:
Probably missed so many tips and tricks in the last two weeks but I can’t remember any upon writing this

Upcoming:
Engine back from painter
Case Closed and most components back in
New piston rings
Electronics tray welded in
Tank mount welded in
Rear seat pin/mount welded in
Rear seat hoop welded to fit better
Back to powdercoater

 

[Motogrady]

On the bondo maybe use less hardener.
Seems awful red in color to me.


Besides that, stellar work so far.

Carb wise, you going with pods?

 

[Nylundarn]

Its really nice seeing someone post all this information with detailed lists and pics. It really helps other builders! I wish I would have taken the time to do it when I built my -79 cafe racer project. Also very good choice on going with the M-unit, love mine.

 

[BeantownBeaverTail666]

On the bondo maybe use less hardener.
Seems awful red in color to me.


Besides that, stellar work so far.

Carb wise, you going with pods?

Thank you for the tip and the compliment! I probably should have specified - I'm using Bondo's Glazing Spot putty. I think I may be using too thick of a glob for this type of application causing it to split. If I can't get it to work I'll change up to what you recommended though.

I do plan to use pods, Uni filters (maybe K&N, not sure yet) with a Dynojet kit to compensate for increased flow. Im sure the tuning and troubleshooting will be fun!

 

[BeantownBeaverTail666]

Its really nice seeing someone post all this information with detailed lists and pics. It really helps other builders! I wish I would have taken the time to do it when I built my -79 cafe racer project. Also very good choice on going with the M-unit, love mine.

Thank you for the compliment and reading through the thread! Always nice to know people are enjoying the build and I'm not just shouting into the void lol. My goal is definitely to help other builders in the future and consolidate answers to any questions I ran into and had to track down while going through this process.

Im excited to get into the Munit and all it's functionality - seems like a really cool piece of tech to give old motorcycles a more modern "brain".

 

[Nylundarn]

Thank you for the compliment and reading through the thread! Always nice to know people are enjoying the build and I'm not just shouting into the void lol. My goal is definitely to help other builders in the future and consolidate answers to any questions I ran into and had to track down while going through this process.

Im excited to get into the Munit and all it's functionality - seems like a really cool piece of tech to give old motorcycles a more modern "brain".

I just love mine, add tons of functionality and its almost the only way to get everything nicely packed under the seat. Im sure you have seen their NFC lock too? The best party trick is turning on the ignition with the key sewn into your riding glove, people cant believe it!

 

[Old_Crow]

Thank you for the tip and the compliment! I probably should have specified - I'm using Bondo's Glazing Spot putty. I think I may be using too thick of a glob for this type of application causing it to split. If I can't get it to work I'll change up to what you recommended though.

I do plan to use pods, Uni filters (maybe K&N, not sure yet) with a Dynojet kit to compensate for increased flow. Im sure the tuning and troubleshooting will be fun!

Yeah the spot putty is the problem. It's supposed to be used as a final glaze for any pin holes or small defects in the bondo before you prime it. A tube of that spot putty ordinarily lasts a professional body guy who uses it every day about 6 months or a year.

Have fun with the pods.

 

[mrtwowheel]

Yeah, when in the business using spot putty is frowned on. Chopped fiberglass filler for deep dents, plastic body filler for shallow dents and over chopped fiberglass filler.

 

[Old_Crow]

Yeah, when in the business using spot putty is frowned on. Chopped fiberglass filler for deep dents, plastic body filler for shallow dents and over chopper fiberglass filler.

Now that you mention it, my body guy had a tube of that stuff and I'm not sure I ever saw him use it in the 8 years he worked for me. I tried it once, before I knew anything about it with similar results to the OP.