Author Topic: questions about a honda c70 1971  (Read 1724 times)

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Offline Tretnine

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questions about a honda c70 1971
« on: July 19, 2009, 03:06:47 PM »
I picked up a non-op 1971 honda c70 today, titled, for $100. I put a carb kit in it, and it's running, although terribly. It only runs with choke on all the way. I don't know what to set anything to, because I've never done scooter work and don't have a manual. There are a number of screws to turn in and out and I put in a new needle, etc.

So, here it is, it runs, but I have to jump on it going down hill and drop it into gear, then most of the time it will start. It winds up really high, and will only run with full choke and if I back it off to half choke or less it dies. If I give it gas, it dies. I have the needle set to setting three out of six. I don't know how far to open any of the screws or how many of them should be opened at all. It pukes out lots of white smoke. I put new gas into it. I have not checked compression, as I do not know what it should be. I do not know what the valve clearances currently, nor do I know what they are supposed to be. I pulled the spark plug a couple of times and it came out real gassy. Well, covered in dark gas. The spark plug is a C7HSA. I do not have a manual nor know an online resource for manuals for this machine.

Help, please! I know someone out there has this info. Thanks, Brady.
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Re: questions about a honda c70 1971
« Reply #1 on: July 19, 2009, 04:15:26 PM »
Sounds like something is still clogged in the carb.  The engine is the same on all the 70cc bikes of the era.  I have a '69 CT70.  There are websites dedicated to the Trail 70 (CT70) that may have the info you need. Google is your friend.
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Offline Tretnine

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Re: questions about a honda c70 1971
« Reply #2 on: July 19, 2009, 05:30:42 PM »
Can someone point me in the correct direction, if it is the carb? I know mostly what's going on in there, but too new to it to diagnose without help. I had it pulled apart and put a kit in, but didn't seem to help.
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2009 Kawasaki Concours, 1978 cb550k, 2006 BMW F650GS

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Re: questions about a honda c70 1971
« Reply #3 on: July 19, 2009, 07:51:26 PM »
You need to use aerosol carb cleaner and if possible, compressed air to clean out all passageways through the carb body.  Some have used something to soak the carb body.  I am using Simple Green currently.  It turns the metal a weird color, but seems to do the trick.  DO NOT USE ANYTHING METAL TO CLEAR ANY BRASS PIECES.  This could enlarge the size of a jet or scratch the seat of the float valve.
Go metric, every inch of the way!

CB350F0  "Scrouching Tiger"
CT70K0    "Sneezing Poodle"

www.alexandriaseaport.org

Offline Tretnine

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Re: questions about a honda c70 1971
« Reply #4 on: July 19, 2009, 08:36:56 PM »
does the fact that the choke has to be on mean anything? Rich or lean? Should I try a hotter plug or will that damage this little engine?
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2009 Kawasaki Concours, 1978 cb550k, 2006 BMW F650GS

Member of the AMA