Results 1 to 18 of 18
  1. #1
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47

    My HONDA "RC-04 project"

    Hello everyone!

    Finally I have decided to show the evolution of my project.
    It's taking shape these last days, and I'm happy with how it's going.

    First of all, I introduce myself: I am spanish and an industrial designer.
    It's my first "big" bike and my first project. And I always had the dream of making/modifying my own bike. And I think there is not a better than this base for that.

    The idea of this post is to share the experiences, problems, solutions and everything else with this community.
    I will also make a brief review of what shit I have been finding, especially in the engine, and how I have been solving them. Unfortunately they are many.

    About two years ago, I bought this beautiful one:







    Honda CB750 F2, 1983, 57xxx km. But the idea is to make this marvel, an even better one.

    THE DESIGN
    Some drawings to illustrate my main idea.



    For the fuel tank, I have on mind to do something like this...



    After some other proposals.



    But still open.

    In the next few days I will show a bit how the process is going.
    They have been two years full of patience and weekends.



    I hope you enjoy to see this, and have fun!
    Tronco.

  2. #2
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47

    The engine 1.0

    Summer 2016: Getting naked!



    The engine was making a strange noise, which I thought was coming from the valves.


    In general was not in a good conditions.

    And after opening to take a look. I discovered that not only had the tolerances in the shims wrong.

    The previous owner screwed up a spark plug badly... Destroying the thread and dropping it into the cylinder.

    Damaging the cylinder...


    More photos:


    I also discovered that the cylinders weren't within tolerances. So I decided to rectify them, 0.25 more.


    Three valves were damaged. two exhaust, and one intake ...
    So new ones and his guides:



    I also wanted to replace all damaged parts, as well as rubber and plastic parts. All those pieces that by use, wear and old age, are sensitive to deterioration.

    At this time, the engine is in the assembly phase, already painted and 100% clean, and with all these new parts:
    Chains, chains skates, rubber bands, O rings, seals ... etc. A lot of money...


    I have to say that this whole process, I've been doing, and I'm doing in my free weekends!
    I will continue uploading more photos.








    As a curious detail: I made my own stand for the engine.


    Hope you like!
    Tronco.

  3. #3
    CB750 Guru amc49's Avatar
    Join Date
    Sep 2015
    Location
    Fort Worth TX.
    Posts
    2,449
    Hope you rechecked valve seats with those guides changed, they never go back in the exact same way and the valve then does not seat correctly.

  4. #4
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Yes AMC! I redo the seats of all valves... New and old.
    you know... rotating the valves with that special paste...

  5. #5
    Moderator dirtdigger's Avatar
    Join Date
    Feb 2012
    Location
    Black Hawk SD
    Posts
    2,813
    Really should have had the seat cut or ground to make the seat contact uniform and concentric. As said guides never go back in exactly as the original and the valve and seat are no longer concentric once replaced. The paste wil not take care of that and the pattern can misleading unless you have done a lot of valves. The paste can smear and make it look like you have complete contact but in reality you dont. I strongly suggest you have the seats cut at a machine shop. They will also make sure all seats are at the same depth in relationship to each other.

  6. #6
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Thanks for the advice guys!!
    I was doing it with a very experienced friend. His motorbikes never had a problem on valves after his hands! 0% oil comsumption.
    And we checked twice!


    "Theorically" if you rotate until you get a 1.5 mm "shiny" surface... You are doing it good. Or that's the manual say.
    http://www.cb750c.com/publicdocs/CB7...rHeadValve.pdf page 18.

    The head now, is ready to mount. So, if you strongly suggest me again... I will think to "redo" the valves again ... XD

    Thanks again!!!

  7. #7
    CB750 Guru amc49's Avatar
    Join Date
    Sep 2015
    Location
    Fort Worth TX.
    Posts
    2,449
    Yours and do what you will but the friend has not done much valvework if he thinks you simply relap the valve on a guide change. You can get the shiny all the way around yet have the valve tilted in the normal guide play and the seat then does not last as the valve will be working slightly angled sideways at all times. It will kill the new guide quick. And, having relapped the valve removes some of the nitride surface so the side loading then cuts through the rest because of unit area loading on one side and then the valve dies too.

    I've had luck with just one falling back into place pretty close but 3 is asking for it. Not doing that in a shop is considered incompetent and not machinist best practice. You can lap the others as they are center on center since the valveseats were cut after the guides were installed.

    FYI, the seats cut but the valves replace only, they cannot be cut.

    Oil consumption has nothing to do with valve seat quality, extended life while still maintaining good compression over the long run is the true test. These particular engines have fits with that as it is and all being in good shape.

    Set the valves at .005" rather than the service manual spec of .003"; they burn very easily at the book spec. They actually can have zero clearance running when measured at .002" and 3 is too close to that, why so many of them run like crap and in a short time. The engines love .005" and last a long time between valve sets like that.

  8. #8
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Friends!
    Now I have understood what you want to say.
    I took the head to a professional workshop, to change the guides. I couldn't do it by hand, obviously.
    But these people know what they do, and what needs to be done in these cases.
    After changing the valve guides, they milled the seats as is normally done. Always.
    That work has been done

    Thank you very much, for the advice!

    But now I have another different problem.
    A pair of connecting rods do not rotate as they should, I even bought two sets of bearings with different thickness. and even with the thinnest one they do not rotate freely in the whole turn, they do resistance in a single point, the rest of the turn does it well.

    What can be? Is it possible that it is not perfect cylindrical?
    I think I'll have to take the crankshaft to the workshop to check the crank connections.

    Regards!

  9. #9
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47

    Headlight brackets

    Hello again!

    Here I want to show my own brackets for the headlight (handmade & design by my self)

    Some sketches... and built it in 3D, like that I can print the perfect blueprints.
















    At the end, they have perfect fitting and are strong enough.


    I hope you enjoy!
    Tronco

  10. #10
    CB750 Addict Wez_'s Avatar
    Join Date
    Apr 2017
    Location
    Enfield, CT
    Posts
    318
    Whoa bro, nice work!! What software do you use for those Alpha images?

  11. #11
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Photoshop!

  12. #12
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Hello again!

    This last weeks I had fun with the frame!!
    But also I want to show you how I made the tray for the batteries. And everything together.
    I have to say, that is my first time welding...

    As always, I start thinking how can I make the things, his form... his elements...




    Cardboard................






    Battery holders...








    Cutting the frame:






    Little Help




    This triangle is to follow the natural form of the frame, and at the same time, make it a little bit stronger.



    Bridge to make a rest for the seat. Because I want to use the same original plastic base, but modified.





    Welding.............

    To better centering of the seat:


    Rear brake light plate...















    Still working on it......... Missing some zones to weld......... cleaning a little all these "beautiful" welds... hahahaha!
    Sanding a bit, and refill all the little holes


    Maybe next step: weld the steering stopers!

    Regards!

  13. #13
    CB750 Member naturals's Avatar
    Join Date
    Feb 2018
    Location
    London, UK
    Posts
    8
    Those welds look good! I'm just embarking on my first build (also a CB750F). I don't think I have the skills to weld my own frame this time round!

  14. #14
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Quote Originally Posted by naturals View Post
    Those welds look good! I'm just embarking on my first build (also a CB750F). I don't think I have the skills to weld my own frame this time round!
    Hahahaha... If I'm honest... I make photos only for the good ones... hahaha!
    I was learning at the same time. But in the visible zones, I didn't care because I wanted to clean a bit...

    Well, I'm still learning.

  15. #15
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47

    Rear Wheel - Laced Mod

    Hello again!

    Here I want to show the modification of the rear wheel, because I wanted to use the same hub with same spacers and everything...





    (50€ old rim)

    You may already know, but there is a web page (which I will not mention) that used to sell a kit to transform the ComStar into laced wheels. I think not anymore.

    But the treatment received by them was not as expected, and the kit never arrived, so I decided to make my own in 3D by modifying plans found somewhere in the huge web.

    And then I did it in rapid prototyping (with the help of a great friend), to be sure that it really fit into the hub, and the holes for the spokes did not interfere with each other (as was the case with the internet plans).













    (This was 4 times cheaper than the web version)

    The final step was to take the set to a professional, to assemble everything in a ring of 17" and 4,5" wide. And painted in black.









    That's all!

    Hope you enjoy!

  16. #16
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Hi guys!

    After a long standby... I can show you the frame painted and brand new mounting bolts for the engine!

















    Regards!

  17. #17
    CB750 Member mitchi's Avatar
    Join Date
    Feb 2014
    Location
    Georgia
    Posts
    19
    Wow.....just wow.

    You have skill. Very nice work/build.

    Can you make me a set of the headlight ears for my 75 SOHC CB750?

    Once again........nice.
    "If it ain't raining, I'm riding"

  18. #18
    CB750 New Owner Tronco's Avatar
    Join Date
    Sep 2016
    Location
    Barcelona
    Posts
    47
    Hi Mitchi,

    Those brackets are specially made for a GSXR 1000 k7/k8 fork... and those black “rings” (check the photo) that are from a Chinese aftermarket brackets (55mm diameter).

    Exactly that ones:
    https://image.made-in-china.com/202f0j00VGJUPBfHvpqR/Quality-CNC-Aluminium-Motorbike-Fork-Headlight-Brackets.jpg

    If you have the same fork, we can talk

    If not, maybe I need more info from your fork... headlight... etc...

    Regards!
    Tronco

Similar Threads

  1. For Sale - 550 "kool grills " for sale make a REASONABLE offer
    By tctreppin in forum Classifieds
    Replies: 4
    Last Post: 05-25-2017, 08:31 AM
  2. "Newbe" '78 CB750A project
    By dan-oh in forum Carburetors / Fuel
    Replies: 20
    Last Post: 10-23-2016, 10:24 PM
  3. Replies: 1
    Last Post: 01-12-2015, 09:26 PM
  4. Carb clean & rebuild, Plastic double "D" washer - Where?
    By 750kjay in forum The CB750 Garage
    Replies: 5
    Last Post: 09-30-2012, 07:29 AM
  5. A look at my 1976 750 project called "Joker"
    By cerberus1950 in forum The SOHC Garage (1969-1978)
    Replies: 4
    Last Post: 03-17-2012, 04:37 AM

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •