CT70 HK0 Revitalization Project

Discussion in 'Projects/Builds' started by Jmunk, Aug 4, 2019.

  1. Jmunk

    Jmunk Member

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    I just wrapped up a Z50 revitalization for my daughter a few days ago and told myself no more projects for a bit. Craigslist is a dangerous place for, I found these two bikes listed as a pair locally. I just happen to look when he posted them and was the first to call. The ad had poor photos and the gentlemen had no history on the bikes except he bought them many years ago and never did anything with them. I was surprised when he pulled out a owners manual for the bikes.

    When I got there I was very surprised to find they were both H models, I promptly paid him as he said his phone was ringing off the hook and loaded them up.

    They both have right around 750 miles and the organe one has a build date of 2/71 and the teal one is 9/70.

    I was thinking of tinkering with the teal one and sending the orange one down the road since the teal is in much better shape.

    Would it be best to just clean the teal bike, get it running and call it a day?

    I’m putting together a list of parts needed from DRATV. I couldn’t find a instrument cluster lens on there, anyone have one they want to part with?

    Also is the head OEM, it has the casting number of E10?
     

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  3. Jmunk

    Jmunk Member

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    Topaz Orange ?
     

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  4. Digginrebel

    Digginrebel Member

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    Sweet finds
     
  5. Gary

    Gary Well-Known Member

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    I have engine ct70he 142836 out of frame 142894 built 11/70 with E9 on its head if than means anything....
     
  6. Jmunk

    Jmunk Member

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    Thanks Gary, sounds like mine isn’t far off and is likely an OEM head.
     
  7. Jmunk

    Jmunk Member

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    I tried to get the teal bike to fire up. I pulled the carb off and verified it has spark, I put a squirt of gas into the intake and after a few kicks it shot a flame out of the intake.

    I checked the valves, the exhaust was set at about .003 and the intake was pretty loose. I set the intake to .002.

    I took a look at the points and it appears I’m the first person to go in there judging by the screw heads. The points looks pretty thin at the contacts. I did my best to set them to .016, but got the same flame out of the intake.

    I’m thinking either the intake valve is hanging open a little or the points are just too worn? I have a new points and a condenser on the way.

    Any suggestions?

    I believe I have the Hitachi setup with the spring advance, this is what I ordered.

    https://www.ebay.com/itm/Ignition-T...3?pageci=02cb1d0e-ae42-407c-b2a4-f47bde493494

    I hope it’s the right set.
     

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  8. kirrbby

    kirrbby Well-Known Member

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    Those parts look correct to me for your Hitachi stator.

    I would try putting the fuel directly into the combustion chamber via the spark plug hole. Replace the plug and kick it over.

    I'm thinking most of your fuel could be sitting above the intake valve...in the head.
    I'd put it into the cylinder.
     
  9. Jmunk

    Jmunk Member

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    Got the new points in and set. I dribbled some gas directly into the cylinder, did cough or anything. I verified the spark was strong and pulled the spark plug and turned the engine over via a drill with my finger covering the spark plug hole, none to very little compression. I put my harbor freight compression gauge on, it wouldn’t move the needle and the carb was off so there was no blockage intake wise. I verified valves were set at spec (.003).

    I need to pull the top end apart. Best case it just needs a piston but I’m sure the reality is it needs a cylinder as well.

    What brand does everyone trust for stock bore piston/cylinder kits and also a 88cc if I decide to go that route?

    I’d rather keep the original cylinder on there but I don’t think value wise in the condition the bike is in that an aftermarket cylinder will hurt an possible
    value down the road?
     
  10. OLD CT

    OLD CT Well-Known Member

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    jmunk, it's very common to have a worn out tuliped/pitted intake valve after 48 years. That will give a low compression reading. If the intake valve sits un seated in the head moisture takes hold, causing pits.. It's best to set the engine to TDC for storage to avoid the pitting.. Aftermarket cylinder will not hurt, a cheap head? YES! That hurts.:eek:
     
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  11. Jmunk

    Jmunk Member

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    I’ll have to take a look when I take it apart and see how the valve and seats look.

    If the valve seats need recut who does everyone use or what is the recommendation? The head on there is stamped E10 and has a “newer” looking finish then what I have typically seen.
     
  12. kirrbby

    kirrbby Well-Known Member

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    I'm with OLD CT on this one. No compression is most likely a problem in the head. Your E10 head is DEFINITELY original to your engine...and worth having rebuilt. PM racerx about doing the rebuild for you. He does a fantastic job with them.
     
  13. Jmunk

    Jmunk Member

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    Thanks for the advice, I’ll reach out to him once it’s off and I can identify the culprit.
     
  14. Jmunk

    Jmunk Member

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    Pulled the top end off, the intake valve is the issue.
    The cylinder looked fairly decent. I think I’m going with a standard size aftermarket piston and cylinder from DRATV unless anyone says otherwise.
     

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  15. OLD CT

    OLD CT Well-Known Member

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    Nothing wrong with using that cylinder and a oem piston and rings. An ''Art'' replacement piston is good too. Don't use just any cheapo china piston. Here is a kit $30.93 shipped with the rings already installed.
    Ebay item# 252983044973 Art piston.jpg
     
    #14 OLD CT, Aug 9, 2019
    Last edited: Aug 9, 2019
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  16. Jmunk

    Jmunk Member

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    Anyone know what brand the DRATV pistons are ?
     
  17. OLD CT

    OLD CT Well-Known Member

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    DRP-1 100025 is the standard bore aftermarket piston. The DRP stands for ''Dragon Racing Products''.
    It's a good piston and is on sale for $24.95 plus added shipping.. Dratv has the same exact ART piston kit for 66 dollars without the rings installed.
    Make sure to follow his ''how to install the rings'' tutorial if you go that route. I would buy the Ebay ART piston kit rings installed that costs the same as his DRP. It is a better deal.
     
    #16 OLD CT, Aug 10, 2019
    Last edited: Aug 10, 2019
  18. racerx

    racerx Administrator
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    Art is OEM of Honda pistons from this era. DRP is good quality aftermarket, been around for two decades. Not likely to have problems with either. All things the same, Art would be my first choice too.

    I do have one further preference...a 3-piece oil ring. Back in the day, Honda used a one-piece, gray iron, oil ring. These are easy to break during installation. 3-piece oil control rings have become the norm because they work better and last longer.

    Dratv sells a number of different pistons, some have the rings packed into a trifold "wallet" with clear instructions. Remember that the letter markings always face "up" regardless.
     
  19. Jmunk

    Jmunk Member

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    Parts have been ordered and head has been shipped out.

    I see CHP sells replacement glass for the speedometer. I would imagine this means that it’s easily replaceable. I haven’t looked at it yet, but the bezel comes off and I can access the glass piece ?
     
  20. OLD CT

    OLD CT Well-Known Member

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    I wouldn't call it easy. You have to be ''very patient'' slowly prying open the bezel with a very small screwdriver prying it open a little bit at a time carefully, all the way around it. There should be more info if you use the search bar.
     
  21. racerx

    racerx Administrator
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    Yep, not the easiest project to execute well...without leaving surgical scars. But, it can be done.

    Find out if the speedometer spins freely and works beforehand. Water can ruin the internals and service parts are rare.
     

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