Topic: 1974 CB750 - cafe/restoration

[Jcop.550]

Back again with my next project(s). Today I went on a little road trip to pick up these two CB750’s. Both sitting together in a barn for the passed 30+ years. Very happy to get ahold of them and bring them back to life.

The orange 750 is the perfect candidate for my next cafe build. This bike is too far gone to restore back to original. The tank and exhaust are completely rotted out. I will have to find a decent tank to replace this one however, I do want to repaint it back to original with the flake sunrise orange color.

The green 750 I am still up in the air with. Not sure whether I want to restore this back to original (after my cafe build) or sell it to someone who would like to take on the project themselves. The tank is nice and the exhaust is salvageable. No carbs, engine seized. The seat will be swapped out with the original one that came on the orange bike if I decide to restore myself.








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[Jcop.550]

Wasting no time! Orange one is the first to go under the knife. Got home and on to the table she goes. Let’s get started!

[calj737]

You might pull the plugs on the green bike motor, fill the cylinders with a 50/50 mix of acetone and atf. Let it soak. Drain the engine oil first. With the carbs off the bike, moisture has likely set in and rusted the rings to the cylinder walls.

After a couple of days, shift the bike up to 3/4 and rock it to see if the motor will come loose. Keep refilling the mixture until it frees the motor. Check the oil pan drain to see how much passes the rings. (Hint: two of the cylinders will be higher than the other pair and take less fluid. It’s the lower pair that are probably rusted up  )

[Jcop.550]

You might pull the plugs on the green bike motor, fill the cylinders with a 50/50 mix of acetone and atf. Let it soak. Drain the engine oil first. With the carbs off the bike, moisture has likely set in and rusted the rings to the cylinder walls.

After a couple of days, shift the bike up to 3/4 and rock it to see if the motor will come loose. Keep refilling the mixture until it frees the motor. Check the oil pan drain to see how much passes the rings. (Hint: two of the cylinders will be higher than the other pair and take less fluid. It’s the lower pair that are probably rusted up  )

Cal, thanks for the info! I’ll give it a try


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[Jcop.550]

A little more details on what I plan to do on this build…

First off, I’ve always loved the look of the Gsxr front end swaps. I have a front end coming in the mail this month. I am swapping the swing arm out with a cb550 one because I think the tube arms look clean plus it is slightly longer. Wider rims front and rear to accommodate bigger/wider tires. The engine is coming out for a deep cleaning, rebuild, and paint. Cafe seat with a removable cowl for the flat style seat to accommodate a passenger. Open triangle look so electrical will be minimized with the m.unit blue all tucked in under the seat. Custom fabricated oil tank. 4 into 1 exhaust. I really love the flake sunrise orange color so I will be getting a tank and having it painted to match the original one that came with the bike. A lot of other little odds and ends but that is the bulk of it! Very excited to be working on another build and to make my vision come to life.


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[Jcop.550]

Got the bike all stripped down. Engine is ready to be pulled for a deep cleaning, rebuild then paint. I’ll also be working on the frame while the engine is out. Removing tabs, seat hoop, paint.




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[Jcop.550]

Orange bike: Engine is out! Time to clean it up and prep for the rebuild.



Green bike: decided I didn’t want to keep it for myself. Just too many projects going on for me to handle and only a one car small garage to work on them. A buddy of mine bought it off me to do his first build. Going to help him along the way and definitely learn more together on these builds.

I am keeping the exhaust and tank. I know the value in a good OEM painted tank and we don’t want to take the paint off and ruin such a classic piece.. got this one stripped down and almost at the same stage as the orange one.

I will keep the updates on both builds in this thread for anyone who wants to follow along!


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[SOHC4 Cafe Racer Fan]

Looking forward to see what you make out of these.

[Jcop.550]

Today I took the rest of the stuff off the bike down to the frame. Worked on removing all tabs I don’t plan on using. Squared away my CB550 swing arm as well. Moving along pretty quick and smooth…for now! We’ll see how it goes.




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[Jcop.550]

Well… here’s the official “before” picture of the engine before I clean it and dig into it. Wish me luck… all a learning process from here as I’ve only rebuilt a CB550 with the help of my brother.




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[Jcop.550]

Quick little update. Stripped the paint off the frame. Waiting on my seat and hoop to come in the mail.

My Gsxr forks came in today so I threw them in just for a little mock up to see what it’s gonna look like.




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[Jcop.550]

New (to me) tank came in the mail yesterday. Started on the prep work. Little more to go but all in all everything is coming along nicely.

Also got my gaskets and rings in the mail so thinking I’m going to start ripping into the engine this weekend/next week. Updates to come.




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[Godffery]

 While your cutting welding on that frame, you might consider installing a removable frame section kit above the motor.  That will allow top end motor work without pulling the entire engine.
 https://www.instagram.com/p/CVLLU65LsRn/

[SOHC4 Cafe Racer Fan]

While your cutting welding on that frame, you might consider installing a removable frame section kit above the motor.  That will allow top end motor work without pulling the entire engine.
 https://www.instagram.com/p/CVLLU65LsRn/

I cannot recommend this enough.  I thought I'd never remove my 750 motor after my 836 rebuild. I removed it 3 times after and each time regretted not having installed a removable frame rail kit.

[Jcop.550]

While your cutting welding on that frame, you might consider installing a removable frame section kit above the motor.  That will allow top end motor work without pulling the entire engine.
 https://www.instagram.com/p/CVLLU65LsRn/

I’ll check it out, thanks for the tip! I sent a follow on instagram, might have some questions about it in the near future- @united.cycles


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[Godffery]

 Okey'Dokey.

 Here is a link to a good quality kit from Ken at cycle x.   http://www.cyclexchange.net/frame__end.htm

[newday777]

Okey'Dokey.

 Here is a link to a good quality kit from Ken at cycle x.   http://www.cyclexchange.net/frame__end.htm

I take it Ken's kit is a weld in kit?
Ken's kit doesn't have the flat center brace pieces like Frank's and Scottly's kits had? I'm guessing to lower the cost.

[Godffery]

Okey'Dokey.

 Here is a link to a good quality kit from Ken at cycle x.   http://www.cyclexchange.net/frame__end.htm

I take it Ken's kit is a weld in kit?
Ken's kit doesn't have the flat center brace pieces like Frank's and Scottly's kits had? I'm guessing to lower the cost.

Yes, it is a weld in kit.  The Bolt in style tend to be a bit bulky and not sure about the overall rigidity? 

 Oh yeah, I hadn't noticed that Ken's doesn't have the flat center brace pieces till you pointed it out?  I wonder if he would provide that if requested?
I have installed at least a half dozen of these types of kits threw the years.  First couple were from a member here on the forum, then started making my own version once I got a lathe and mill in the shop.

[Jcop.550]

After a few hurdles, got the top end all torn apart. Time to refresh, paint then rebuild.





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[Jcop.550]

Finished painting the engine. Waiting on a couple parts to come in the mail and it will be time to put it all back together! So far, I’m loving how it’s turning out.




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[Jcop.550]

Lots of updates and pictures coming. Starting with the seat and seat hoop. Got my seat in the mail from the upholsterer and the hoop welded on. I went with a flat seat with a removable cowl so I have the cafe look with the option to remove it for a two seater. Black with orange accent thread.







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[RAFster122s]

You aware the tire can come up pretty far at full compression, most hoos have the kick up at the end to maintain stock clearance. You do not want to experience a tire contacting the underside or hoop...the results can be pretty ugly.

[Jcop.550]

You aware the tire can come up pretty far at full compression, most hoos have the kick up at the end to maintain stock clearance. You do not want to experience a tire contacting the underside or hoop...the results can be pretty ugly.

Yeah I’m aware. My first CB cafe build has the same style hoop and seat. Been riding it for a while now and have had no issues even with a passenger on.


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[calj737]

The tire doesn’t hit the hoop; it can conflict with the seat pan. A smaller rear tire, modern quality shocks both solve that issue if you encounter it.

[Jcop.550]

Got the engine all painted and put back together. Just have to polish up a couple more parts tighten everything up and hopefully come across a points cover that isn’t dented/scratched.




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