1974 CT70 K3 Restoration Project

Discussion in 'Projects/Builds' started by ArcticMinibike, Oct 7, 2016.

  1. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    I'm starting to get this project underway so I'll officially start a project thread. My 1974 CT70 K3 that I've had since my young teen years in the early 80's. I haven't decided if this will be a concours or not. Probably not a 100 point job, but maybe down the road, who knows. Doing a candy repaint scares me the most and there's no budget at this time to hire it out. I want to leave my options open, but not spend a mint just yet. More pics to follow.



    I've already acquired the correct new OEM exhaust and muffler assembly. That will get shelved for a while. I also have a half decent set of chrome fork ears and the original turn signal stalks, all of which will also remain in storage indefinitely. I've ordered a few other parts as well. I'm starting with the OEM stuff I know might be limited or scarce in the near future. First priority is to swap out the cracked head, clean out the tank, redo the carb and lines and get this thing running.

    Major Damaged items include:
    - left and right signals/switches. I will get a new left side signal/horn, no problem. As for the right hand dimmer/run/stop switch, I have the housing, but the internals are broken off and red knob tail broken. I will look into harvesting or acquiring used parts.

    - chrome fork ears. I have a half decent set of chrome fork ears and the original chrome signal stalks I got with the bike back in the early 80's. They'll need polish or probably re-chrome. Lots of other minor worn or cosmetic parts to buy.


    Other items, many cosmetic, include:
    - new cables (current ones work, but are a little worn)
    - carb rebuild kit
    - throttle kit if cleaning doesn't loosen it up and new OEM '74 grips
    - top end rebuild and all associated parts (possible valve seat cutting)
    - clinder bore/piston/rings
    - possible full engine rebuild, this bike has a lot of miles on it
    - new fuel lines
    - tank liner
    - new seat (I'd be fine with a good solid pan, as my foam is good, just need the correct cover and chrome trim strip)
    - battery
    - ignition tune up kit
    - possible new wiring harness
    - various seals, gaskets and replacement screws
    - shock rebuilds
    - wheel repaint (they're decent already and might clean up fine.
    - frame clean-up (may eventually strip and repaint, but not ready to spray candy riviera blue just yet)
    - straighten the bars, and possible chrome job.
    - headlight bucket needs some attention, as it has a little surface rust
    - at least 1 turn signal chrome housing

    I'm lucky, most everything is there and in decent shape. Thanks to my dad for keeping it in the garage since 1984 when it was mothballed for a cracked head.

    Thanks in advance for the knowledge I'm about to receive. I've been on other forums for many years that don't have the friendly quality vibe this one has. I'm looking forward to this.
     
    #1 ArcticMinibike, Oct 7, 2016
    Last edited by a moderator: Aug 22, 2017
    Smitty Blackstone likes this.
  2.  
  3. b52bombardier1

    b52bombardier1 Well-Known Member

    Joined:
    Dec 26, 2010
    Messages:
    1,873
    Likes Received:
    131
    Sounds good. Just curious how / why the head would have cracked???

    Rick
     
    #2 b52bombardier1, Oct 7, 2016
    Last edited by a moderator: Jul 17, 2017
  4. Ponytail

    Ponytail Active Member

    Joined:
    Nov 24, 2013
    Messages:
    280
    Likes Received:
    72
    Looking forward to following your build.
     
  5. cjpayne

    cjpayne Well-Known Member

    Joined:
    Jul 26, 2012
    Messages:
    5,306
    Likes Received:
    423
    I have a '74K3 cylinder head stashed at my brothers. I can't remember what the head casting number is off hand. Post a pic of the head number and I will see if it matches. This head is a good casting, just needs the usual, and is bagged up. The head number is located between the intake valve cover and the big round cam cover. When you order your carb kit, be sure to also get the float valve needle and it's brass seat. Those old float valve needles can/will stick if they've been sitting for awhile. The only way to fix them is to replace them. Don't be afraid to ask stupid questions here, because you may feel stupid for not asking later.lol
     
    Smitty Blackstone likes this.
  6. kirrbby

    kirrbby Well-Known Member

    Joined:
    May 28, 2009
    Messages:
    8,309
    Likes Received:
    979
    I'm also interested to know what's up with the cracked head. Please elaborate on that as you get started with your build.

    I also look forward to following your progress. K3's make for great build threads IMO. They have a lot of good parts, and are beautiful when complete. Good luck to you.
     
  7. samstheman

    samstheman Active Member

    Joined:
    Aug 3, 2016
    Messages:
    207
    Likes Received:
    42
    Let your build begin post pics.
     
  8. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    Question #1 (of many): As I'm ordering parts, I need advice on these. I ordered an OEM black chain guard which I can paint to match one of these days. I need to address the broken flywheel cover. The damage isn't huge, but will show even with the new chain guard. The only OEM option is with the modern one piece cover. To keep the 2-piece design and use my existing points cover, I can only find reproductions. $100 on ebay isn't an option. My budget unless it's a must. Should I hold out to find a used unbroken original or go with one of these other ones? Does using a reproduction part like this violate the sacred concours code, should I ever go that far with this bike? If reproduction is fine (assuming the visible side of the casting is an exact match), anyone know if the quality of this part is better between dratv and CHP? Both offer them. Thx.
     
  9. cjpayne

    cjpayne Well-Known Member

    Joined:
    Jul 26, 2012
    Messages:
    5,306
    Likes Received:
    423
    I have an unbusted cover from the same K3 the head came from. Will PM
     
  10. kirrbby

    kirrbby Well-Known Member

    Joined:
    May 28, 2009
    Messages:
    8,309
    Likes Received:
    979
    Those repop parts are pretty nice, but they have one obvious difference from the original. There is a bevel along the lower right edge, similar to the early Z50 covers. It does not belong on the 2 piece ct70 cover. I believe dratv and chp parts are identical.
     
    Smitty Blackstone likes this.
  11. CTKing

    CTKing Active Member

    Joined:
    Feb 15, 2014
    Messages:
    360
    Likes Received:
    36
    DrAtv has a great repop cover for like $20. Just use your points cover and your good to go. In regard to the bevel on the edge I'm going to have to dig one of mine out and take a look. I was totally unaware of this.
     
    #10 CTKing, Oct 8, 2016
    Last edited: Oct 8, 2016
  12. kirrbby

    kirrbby Well-Known Member

    Joined:
    May 28, 2009
    Messages:
    8,309
    Likes Received:
    979
    It's really a shame that the repop has that bevel. I think it's still a great part. It's weird too that they would have...basically combined two different parts when they were copying the one. It seems like you could just make a mold of the original, and use it to make more. lol Instead, they created a whole new part.
     
  13. OLD CT

    OLD CT Well-Known Member

    Joined:
    May 15, 2006
    Messages:
    4,184
    Likes Received:
    594
    No need to dig one out, this is the aftermarket piece. If you want a perfect all original, you need patience to get one at a reasonable price.
     

    Attached Files:

    Smitty Blackstone likes this.
  14. kirrbby

    kirrbby Well-Known Member

    Joined:
    May 28, 2009
    Messages:
    8,309
    Likes Received:
    979
    I'm betting CJ hooked him up with a winner.
     
  15. CTKing

    CTKing Active Member

    Joined:
    Feb 15, 2014
    Messages:
    360
    Likes Received:
    36
    All be dammed your right Kirrbby! Never noticed that before.
    Maybe it's time to start a new business. 3D print OEM parts! $$$$
     
    #14 CTKing, Oct 8, 2016
    Last edited: Oct 8, 2016
    Smitty Blackstone likes this.
  16. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    Well, I have no idea HOW it happened other than the primary drivers of this bike at the time were me and my brother, twin 14 year old boys who wanted a Yamaha YZ80 or YZ125, but this is what we got instead. So, we might have ridden it a bit hard, jumped it, etc. ;)

    So, if you guys are sitting down, brace yourselves...here is why we parked this back in the mid 80's.


    I can't understand what could have happened to cause this. Back then, we installed new piston rings, and possibly a piston. I'll have to go back to my pics from disassembly, but I wonder if we put the piston on upside down. Could there have been contact with the intake valve? That would have jammed that valve stem up, putting pressure on that rocker, pin, and casting. Sound possible? From my pics, the triangle on the piston crown was pointing down. The valves have even carbon coating and don't appear to have made contact. The only other thing I can think of is a faulty casting, but that doesn't seem likely.

    The good news about this is that because it was broken, the bike sat unused (unabused) in my dad's garage for another 35+ years. BTW, nobody tell my twin brother what this is worth. He gave up ownership to me long ago and just wanted "that piece of junk" gone. This is MINE all MINE. :p
     
    #15 ArcticMinibike, Oct 9, 2016
    Last edited by a moderator: Aug 22, 2017
    Smitty Blackstone likes this.
  17. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    Busy afternoon... For now, I'm cleaning it by the disassembly method. I'm not ready to do a full strip down and paint yet. I'd like to get it clean and running, so I just pulled off as much as possible to assess the situation. For now I need to fix the head, maybe replace the piston/rings, clean and check the clutch, rebuild the carb, new lines and clean the tank.
     
    #16 ArcticMinibike, Oct 9, 2016
    Last edited by a moderator: Aug 22, 2017
  18. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    Question #2: Can I have the fuel tank powder coated without the heat affecting any of the joints or integrity of the connections? I wasn't sure if it has any sort of seal in the joint or low temp brazing of fittings. I have a distant relative who does free powder coating for me. The inside has old gas resin coating, so I'll be cleaning it before painting, regardless of the type of painting. The tank is very sound.

    Suggestions on internal cleaning method? I don't have the budget to have it done professionally I'm sure there are plenty of threads out there on using acids, Evaporust, post-cleaning sealants, etc..

    Post cleaning, should I coat the inside with a tank liner product, or just keep it clean?
     
  19. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    Question #3: Worth the money to pay double for an OEM ignition coil? $34 vs $70, and it sits way down in there...invisible, but I'm assuming it's easy to tell even by looking at the wire. My coil (blue coating) was fine back in the day, so I have no reason to think it has any problems. However, I noticed a spot about 2 inches from the boot where it's possible the wire is broken or weakened. Unless there's a way to replace just the wire or splice it where it sits up in the frame, I might need to replace the whole assembly. More money I didn't want to spend.
     
  20. samstheman

    samstheman Active Member

    Joined:
    Aug 3, 2016
    Messages:
    207
    Likes Received:
    42
    Evapo rust works once clean u can get a sealer for the inside. I powder coated my 50 no problem and I let the powder float inside the tank and I bake it in there too to seal it up.
     
  21. ArcticMinibike

    ArcticMinibike Active Member

    Joined:
    Sep 19, 2016
    Messages:
    208
    Likes Received:
    54
    I see that NKG makes a spark plug wire splice. I also found it, as well as the 7mm wire, for sale on DRATV (cheaper than other sources) and with good reviews. I'll have to check the condition of the coil wire up in the frame. That being said, I'm still curious if buying the OEM coil is worth the extra $35 over aftermarket, just in case I go that route. I guess that comes back to concours/not concours.

    I'm assuming that there's very little chance my original coil went bad by sitting indoors, unused for 35 years.
     

Share This Page