CL175 rebuild

Discussion in 'Old's Cool' started by jtn, Jun 18, 2009.

  1. jtn

    jtn Been here awhile

    Joined:
    Oct 7, 2006
    Oddometer:
    120
    Hi folks, thought I'd share a project that just found me --

    Saw this sign on a rusty 1970 honda cl175 on the side of the road in the rain.
    [​IMG]
    Who could pass it up? Engine turns over, but doesn't start. Maybe something to do with missing the battery.
    [​IMG]

    I'm hoping to turn it into something like these:
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    [​IMG]

    Any leads on on-line repair manuals for this era? It seems like the CL series shares most parts with the CB's of the same years (except the exhaust headers, side cover . . .) so could I just get cb 175 parts and it'll work? I'll put up more pics as I make progress . . .
    #1
  2. nedodjija

    nedodjija Been here awhile

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    My understanding is that lots of people like better CB160 than 175s because of the difference in the frame and because 160s have overhang engine. However, you cannot beat the price on that baby. Those bikes look awesome. Please keep us posted.
    #2
  3. jtn

    jtn Been here awhile

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    Pulled the carbs out today, and there was a ton of corrosion. Got them soaking in some gas for a while and hopefully that will help. What do you all think? The throttle body wouldn't even slide up & down, so I don't know if its worth the effort to refurbish the carbs or just find new ones.

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    Tank is shot, and I'd like to replace it with one that has those knee pads on the sides -- were those for the cb160's? Will they fit a cl175?

    [​IMG]

    Spark plugs and top end didn't look that bad (except for the corrosion on one plug):
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    #3
  4. Yad

    Yad yet another dave

    Joined:
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    gas won't help. There are many ways to clean carbs, do some searching and you will find details.

    1. carb dip in a big can (toxic but effective). Not the aerosol stuff, that only works after they're already clean.
    2. ultrasonic cleaner (can be expensive unless you already have one)
    3. degreaser (e.g. Purple Power) to get rid of gas residue (brown stuff)followed by acid (SHORT exposures, not soaking) to get rid of oxidation (white stuff). I use toilet bowl cleaner and a toothbrush. Just a couple of minutes at a time won't harm the parts, and it really helps nicely with the white stuff. Doesn't help with the brown stuff.

    This is one of my favorite jobs in motorcycle refurbishment. Regardless of which method you choose, it's definitely worth trying to salvage them. I have very rarely needed to actually replace carbs, nearly all of them can be saved with thorough cleaning, although you are very likely to need parts (jets, float needle and seat, at least).

    Good luck!
    dave
    #4
  5. Yad

    Yad yet another dave

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    P.S. I strongly recommend securing a valid title before you spend any significant time or $. Depends on your location, but in some places it borders on impossible to title a bike like that if you cannot get the previous owner to do it (in that case, it's easy). Do some searches on this. Fair warning.
    #5
  6. EvilClown

    EvilClown Reality show stunt double Super Moderator

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    Nice find.:thumb


    :lurk
    #6
  7. jtn

    jtn Been here awhile

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    Thanks for the advice -- I figured if it got close to starting I'd look into getting the title, if not then I'd just give it to someone who has more patience than I do.

    That said . . . the current goal is to get the engine to run then I'll worry about the details (brakes, lights, gas tank . . . )

    Cleaned the carbs (toilet cleaner followed by spray carb cleaner did the trick!) and reinstalled them:
    [​IMG]

    Drained and replaced the oil (I figured if I got stupid lucky and it actually started I didn't want to mess up anything)
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    Pulled the key ignition and hotwired it
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    By the way, this is why you need big guage wire when hooking up the battery :baldy
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    Hooked up a temporary gas line & filled it with gas (there's no tank, just got the float bowls full and used that)
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    And then gas puked out of one of the carbs -- forgot I stripped the drain thread and found a little hole in the side of the float bowl too. Hot glue to the rescue.
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    #7
  8. jtn

    jtn Been here awhile

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    So, the next step was to push the start button. The starter actually turned over, which is better than I expected, but the engine didn't fire up. So I checked the spark by pulling each plug and grounding it and hitting the starter, and both had a spark (not pictured here b'c I don't have three arms)
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    Then I thought maybe the compression was off, so I put my thumb over the spark plug hole and turned the engine over -- the R cyl had some pressure (I couldn't keep the air from pushing past my thumb), and the L had some but less (I could hold it in with some force). Not enough compression to fire? I'm not sure, but my gut says that wasn't the problem.
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    Thought I'd test it with my compression guage, but it didn't fit the spark plug hole. Anyone know of an adaptor for this?
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    So after trying again, I thought maybe the engine is flooding. When I pulled the plug on the L side I noticed that the end was damp
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    And that there was some gas leaking out the air intake for that carb on the L side too
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    But the R side seemed fine. I would have thought if 1 side worked and the other didn't as well, the engine would still catch and just run poorly. Maybe not?

    So, I got frustrated and just steel wooled the exhaust manifold.
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    Any ideas? What should I try next? I've got a spark, gas, and air in the cylinders, what else do I need?
    #8
  9. postaldave

    postaldave gone postal

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    i strongly recommond you take Yad's advise. i've seen dream crushed over a title issue.


    #9
  10. EvilClown

    EvilClown Reality show stunt double Super Moderator

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    I'd get that carb leak ironed out and throw in a some new plugs - or at least clean the old ones. A match in the cylinder will burn out the gas and your finger tips if it's flooded. One of those long lighters will usually save the fingers.:lol3

    Once all that is done try starting it by spraying WD40 in the carbs. If it runs on that it'll run.:deal
    #10
  11. Lukengruven

    Lukengruven n00b

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    I've got a '73 cl175, and I'm trying to sort out the left carb. perhaps anyone could lend some advice.
    the slide is tight in the tube, I've clean and cleaned it. it slides freely in the right carb, but not the left carb.
    does anyone with this bike happen to know or remember the numbers on the slides on the carbs?
    mine has a 155/25 in the left and a 156/25 in the right.
    I am scouring the internet to see if those are different
    part numbers for the left/right, or sizing designations.
    If anyone has any input, that would be great, thanks!
    #11
  12. jtn

    jtn Been here awhile

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    No luck -- the good news is that the electric start works -- it's turning the engine over but it doesn't catch, even with the new plugs. I'm getting stumped -- any ideas?
    #12
  13. EvilClown

    EvilClown Reality show stunt double Super Moderator

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    A couple o questions: Is there a (reconfirmed) spark? What do the plugs look like? How did you go about spraying the WD40 (go into detail)? Have you found that compression gage adapter yet?
    #13
  14. jtn

    jtn Been here awhile

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    Got 25 psi in one cyl, and 40 in the other. Took it as a sign that I should learn to recondition valves & pistons. the rings on one were totally stuck and broke right off (looked like water was sitting in the cyl).
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    The head looked pretty corroded so I put the valves on a wire wheel and am in the process of lapping them. lots of carbon build up and rust, so I think that's where I was loosing a bunch of compression.
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    Anyone have thoughts about the cam chain tensioner? looks like the teeth got worn off, but its just a tensioner, so . . .
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    I'm also getting good at breaking bolts and not extracting them correctly -- time to learn how to use one of those keenserts
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    And we're down to the crankcase.
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    Meanwhile I took everything down to the frame and got a new (less rusted) gas tank from Bill's Bonyard
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    And plan to strip the tank paint (leaving it burnished steel with a clear-coat) and repaint the frame matte black
    [​IMG]

    I honed the cylinders and orders some new rings, so hopefully those will be in soon and I can start the re-build . . .
    #14
  15. Quickv4

    Quickv4 Pro Turd Polisher

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    Refirbing a bike (that seems utterly abused and neglected), with NO TITLE.....:deal

    Been there done that, wouldnt EVER do that again.:doh

    Life is so much nicer when you have a title, regardless of the bike's condition! It gives you a motivation as in- "If I get this thing running and ridable, all I then have to do is skip to the DMV, and shes all kosher, lets ride!!!!)
    #15
  16. SOS

    SOS Ignorance is a gift

    Joined:
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    The cam chain tensioner is the weakest link in the Honda twins from the '70s. Your cam chain will go out of adjustment, constantly change your timing because the points are driven from your cam and the relative position between your crank (pistons) and your cam (valves and points) will always be changing. It will also start slapping on the side of the cylinder casing and throwing metal shavings into your sump.

    You've gone this far...You need a new tensioner!!! Here is the Honda part number for a CL175 K6 (serial number starting with CL175-7XXXXXXXXX) 14501-216-000. The other years are probably the same, but check for your year. It is probably still available through your local Honda dealer and should be $50 or $60.

    Cool project by the way:D . I love the little Honda twin street bikes. I have a CB360 / CB350 cafe that I am working on too. It is on the road, although not pretty, and it is a blast.

    For the carbs I recommend that you pull them and soak them in some carb cleaner while you are waiting on the rings. There are small passages that spray cleaner will not touch. Also, pull the jets and emulsifier (Did I spell that right:huh ) tube and clean them separately. The pilot jet will never come clean by soaking alone, use a wire bread tie or some 0.009" guitar string to clear it out. It will run with it clogged but not very well.

    :lurk
    #16
  17. kevw

    kevw n00b

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    Scotland!
    Cool! I love 175's!

    Yeah, get a new cam chain tensioner.....put the engine back to gether properly so you only have to do it once.

    Looking at the state of your carbs, I would try and find a new set. If they do clean, so they won't cause probs I'll be amazed.

    Excellent project though.....keep the pics coming
    #17
  18. jtn

    jtn Been here awhile

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    Thanks for the info & p/n -- I've heard rumors that there is a steel wheel replacement that was used on the bigger CB's -- any idea if that would work or where to find one? Most of the parts I'm finding on eBay look pretty busted up, and the OEMs are pushing 100 bucks.

    By the way, I'm thinking of putting in dual headlamps like the triumphs:

    [​IMG]
    #18
  19. D-Mac

    D-Mac Been here awhile

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    Will the stock electrical system be able to handle 2 headlamps? I know my CL350 probably couldn't. The original bulb is only 25/35w I think.
    #19
  20. SOS

    SOS Ignorance is a gift

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    The electrics will not handle a double headlight. You could mount two headlights and wire one up for the low beam and the other for the high beam, but then you wouldn't be getting anymore light out of it. It would look cool though:D .
    #20