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Author Topic: 1980 Honda CB750K Bratish first build  (Read 411 times)

Offline JTM88

  • Posts: 5
1980 Honda CB750K Bratish first build
« on: Jun 10, 2019, 23:10:31 »
I'll start out by saying that this is my first build, I guess the title gave that away ;D. I've been wanting to build up a classic bike for the past 10 years, but living in an apartment made that kind of difficult. Fortunately my wife and I where able to purchase our first house this year, and once we got settled in it was time for a project.

Week 1
So after messaging a few people on CL and not getting any responses back I finally found a guy selling a 1980 CB750K that was in pieces. At first I wasn't sure about buy a motorcycle puzzle but then I realized had had basically done the first half project just in getting it taken apart!




The first thing I did was to start mocking everything up.



At this point I decided to go with super bike bars, originally I wanted to build a cafe racer, but after having sport bike I just didn't want to do clip ons again. I think the low bars and CB750F rear sets give it a sporty enough feel.

I went with bar end mirrors with integrated turn signals, I wanted to keep a minimalist theme as much as possible. I also bought some "brown" grips off of eBay, brown must mean something different over there (they are getting replaced soon)


Week 2
Nest step was to strip the paint off the tank. At first I trained aircraft stripper, but all it did was make a mess. So after getting fed up with it I went to town on it with a wire wheel. This took care of the paint in no time. Also I can't believe how thick the paint is on these tanks.


During the same weekend I also made some custom bolts out of 303 stainless for the swingarm and engine mount. I could not find the factory bolts for these rear sets anywhere. Plus I think these look cooler.


Next I tackled cleaning up the valves and lapping them. Chucking them on a drill made and using a scotch bright pad made quick work of cleaning off the carbon buildup. Then I set off to lapping them.



Then I re-installed the valves with new seals.


Week 2.5
Apparently an extra seal was included to make me think that I had forgotten to install one.


So all the valves were taken out once again to be checked.


Week 3
I had ordered my shocks a few weeks ago and they finally arrived. I decided to go with RFY shocks that I would send off to get rebuilt. After a rebuild they should function very well, plus they just look cool and the price is right.




Week 4
After I took the paint off of the tank I thought that I wanted to keep it raw, but after looking around I felt like that had been done a lot so I went with my original color idea, white. I did a base of self etching primer, then 6 coats of Duplicolor Perfect Match Universal white, and finally 4 coats of 2k clear.




Once it dried for 24 hours I wet sanded and polished it up, I think it came out pretty good IMHO.


I also got my gauges from Dime City Cycles and mounted them.


Oh yeah and the seat from Texavina. I'm surprised I don't see more of his seats he has a ton of options for a bunch of bikes. I decided to go with a seat that has space for a passenger in case my wife wanted to ride, and I like how it's raised in the rear to give it a little more character and support.


So that is where I'm at as of now, I still have a ways to go, but I can see the progress.

Next I'm going to tackle the engine assembly which is a little daunting since I've never put a 4 stroke back together.

Offline pidjones

  • Posts: 997
Re: 1980 Honda CB750K Bratish first build
« Reply #1 on: Jun 11, 2019, 08:39:11 »
Good progress. I hope you didn't lap the valves too much - they are hard faced, and it isn't very deep. Using the lacquer with 2K clear is what Maritime did on his GL1000, and I did it on mine. I think a lot of folks are using Rustoleum appliance paint on frames. Have you started on the carbs yet? There is a great instruction here: http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revG.pdf
"Love 'em all.... Let God sort 'em out!"

Offline JTM88

  • Posts: 5
Re: 1980 Honda CB750K Bratish first build
« Reply #2 on: Jun 11, 2019, 10:06:16 »
Good progress. I hope you didn't lap the valves too much - they are hard faced, and it isn't very deep. Using the lacquer with 2K clear is what Maritime did on his GL1000, and I did it on mine. I think a lot of folks are using Rustoleum appliance paint on frames. Have you started on the carbs yet? There is a great instruction here: http://www.cb750c.com/publicdocs/SeanG/Honda_Carb_Manual_revG.pdf

Thanks, I tried not to lap them too much I guess I'll see how long they last when I get it back together.

I'm definitely going with the appliance paint, after looking around here and on some other sites it really seems like the way to go if you don't want to spend the money on PC.

The previous owner said he already rebuilt the carbs. I haven't decided if I want to take them back apart to double check his work or just see what happens when the bike goes back together.

Quick question though, is there a trick for getting the hardened carb boots off?

Offline pidjones

  • Posts: 997
Re: 1980 Honda CB750K Bratish first build
« Reply #3 on: Jun 11, 2019, 18:18:55 »
Heat and patience. I used a heat gun and was able to use the original boots that were on the bike when the parked it in 1999. Heat to pull, heat and lube with a little silicone and use a ratchet strap to replace. Oh, and pods are the devil. Good luck getting CV carbs to work right with them.
"Love 'em all.... Let God sort 'em out!"

Offline JTM88

  • Posts: 5
Re: 1980 Honda CB750K Bratish first build
« Reply #4 on: Jun 11, 2019, 18:23:41 »
Heat and patience. I used a heat gun and was able to use the original boots that were on the bike when the parked it in 1999. Heat to pull, heat and lube with a little silicone and use a ratchet strap to replace. Oh, and pods are the devil. Good luck getting CV carbs to work right with them.

I have no intention of using pods, after reading about them I've decided to stick with a factory air box.

Offline JTM88

  • Posts: 5
Re: 1980 Honda CB750K Bratish first build
« Reply #5 on: Aug 02, 2019, 12:06:49 »
So I've made quite a bit of progress in the last few weeks.

- The engine is all back together
- The frame has been Painted
- The engine has been installed in the frame

After finding out the forks were bent I decided to swap a set of GSXR 750 forks onto the bike as well as a CBR600 F2 rear wheel. I feel a whole lot more confident in the braking ability of this bike now.



Offline Jimbonaut

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Re: 1980 Honda CB750K Bratish first build
« Reply #6 on: Aug 02, 2019, 12:48:57 »
Looking great man, and yeah same same on the extra valve seal.  I found an extra one in the bag, thought I'd missed installing one and redid the whole job. 

Great looking bike!
"I'm telling you Donnie, nuthin' but nuthin' but right"