Preparing my daily ridden 1982 Honda C70 for our biggest adventure yet

Discussion in 'Battle Scooters' started by slowlane, Nov 11, 2012.

  1. slowlane

    slowlane Adventurer

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    Hello everyone. Since this is my first post I guess I should first make a quick introduction for my bike. It is a little red 1982 Honda C70. I bought it back in October 2005 while living in rural Kansas because the C70 looked like a lot better way to get around than the old bicycle I was riding at the time. It had 3200 miles and had probably been sitting in a back yard for about 15 years. With a little work I had it running but some shifting problems eventually led me to completely tear down the engine only to find much destruction. The bike had probably been run low on oil, burning up the piston, cylinder, and connecting rod small end. Two of the four screws that held the clutch assembly together had fallen out and were floating around the bottom of the engine case. I fixed everything and began using the bike as daily transportation and for weekend/after work fun. I rode it on thousands of miles of Kansas dirt roads and trails. All was good. Then I lost my job and moved back with my parents in Texas where I am to this day. Through all of this, the Honda has been my main mode of transport. During our more than 27,000 miles together, I have developed a strong attachment to the little bike and could not imagine my life without it. Consequently when I decided that I want to make a major cross country ride the summer after next, I can see no other motorcycle to take than my faithful, Honda C70.

    This thread will document the few modifications and additions that I am making to my C70 in order to make it better suited for a coming long, demanding ride. Basically I am going to do only the upgrades considered a necessity for a bike to survive the route I am planning to travel. I am adding a bash guard for the engine which I am building from scratch because as you would expect, there are no aftermarket shields for Honda Super Cubs and the CT90-110 guard would require significant modification to fit the bike due to the air box and exhaust differences. Even though my C70 averages about 110 mpg, the gas tank only holds a gallon, unacceptable for my coming travels. So, I am going to build an addition to the factory rear rack to mount a pair of Rotopax 1 gallon gas cans, one on each side. To cope with the extra weight, I ordered a set of heavy-duty adjustable rear shocks that are about 3/4" longer than stock. I'll post pictures and updates as work progresses.
    #1
  2. slowlane

    slowlane Adventurer

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    I spent several hours Saturday and Sunday building the bash guard for the engine. It is nearly done and just needs some finishing touches and paint.

    Here is the C70 with the leg shied removed ready for the construction to begin
    [​IMG]

    This is the stuff that I have to build the guard. Two 3/4"x3ft lengths of pipe, 1/4" plate steel, and a left over piece of 18 gauge floor pan from my Dad's '65 Buick Riviera.
    [​IMG]

    First I made these pieces that attach to the bike's brackets that normally hold the leg shield
    [​IMG]

    Next I welded a 3 ft section of pipe to one of my brackets and bent the left side support tube. I have no tube bender for pipe that big, so I had to make pie cuts in it and kink it to form the "curves".
    [​IMG]

    Then I cut/bent the right side tube.
    [​IMG]

    After that I cut a seven inch section of 1/4" plate to make the rear mount. I drilled holes to attach this piece to the front foot peg mounts. I bolted everything up to the bike and welded the tubes to this rear brace. I tacked all the cuts I had made to bend the curves and then removed it from the bike for final welding. This is the result.
    [​IMG]

    Finally I cut a section of the old Buick floor pan that would serve as the skid plate section of the guard. I reshaped the curve of the left leg of the guard at this time to match the right side. I didn't like the asymmetrical look. I then welded the skid plate to the bottom of the legs, finishing the bulk of the bash guard construction. Now it just needs some minor upper mount work, a hole drilled for oil changes, and then paint.
    [​IMG]
    #2
  3. vtwin

    vtwin Air cooled runnin' mon

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    subscribed!
    #3
  4. JHOLEAHOLE

    JHOLEAHOLE junk show

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    as a fellow '82 C70 owner i am wishing you the best! god knows they are durable
    #4
  5. JerryH

    JerryH Banned

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    I used to have an '82 C70 bought almost new in '83. Those things were tough. More recently I considered a new Symba, but they seem so flimsy compared to the real thing, even if SYM made it. The C70, or "Passport" as it was called, would go anywhere, and always get you back. I'm actually 2 big for one now, though I have no doubt that a real one would be able to carry me around just fine.
    #5
  6. MacNoob

    MacNoob piney fresh

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    I have an '82 as well. Mine has 26,000 km and will still touch 50 MPH on occasion. Looking forwards to seeing what you do with yours.
    #6
  7. r1200gs_chris

    r1200gs_chris Been here awhile

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    * subscribed *
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  8. LookOutLinn

    LookOutLinn Strom Trooper

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    I'm in too.
    #8
  9. bayoulubejim

    bayoulubejim Banned

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    Xr 100 tank is a pretty much bolt on and adds 1.5 gallons. Get rid of the leg shield. Gets in the way of bigger carb and free flowing air filter. Bump the engine up as much has you can afford. Gear it taller. Then carry an extra cylinder and piston.

    Get rid of the bash plate. No need for it unless you plan on jumping rocks. You are only going to be able to do gravel roads, light trails with it anyway.

    Ask this guy some questions too. http://www.dualsportridersoflouisia...rt-to-Adventure-Or-the-slow-way-to-Daytona-FL
    #9
  10. chazbird

    chazbird Long timer

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    Very interested in how your story develops. I've a '81 C70, (and a few previous one's and a couple of S90's) and a Symba. Even though I have a Symba, which is "better" in all respects, I too can see no reason to ever part with the Passport.
    #10
  11. slowlane

    slowlane Adventurer

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    Thanks everyone for the interest in my thread.

    JerryH I also happened upon a dealer a few years ago selling Symbas. I saw them from the road at speed and thought they were Honda Cubs. I went in to check them out but the price instantly turned me off. I could have several real Cubs for as much as the Symba cost. No thanks. The guy who owned the dealership kept trying to tell me that my '82 was built for Honda by SYM. Ha!

    JHOLEAHOLE thanks yes they are crazy durable even though they may not look it. Mine has been through some pretty wild things, including being hit by a Lincoln, and always makes it home.

    MacNoob mine will cross 30,000 miles any day now and will still hit 50 under perfect conditions but 40-45 is normally where it likes to hang. I remember shortly after I got it running well I rode it full throttle down a long hill and buried the speedometer but was still accelerating. I probably hit about 55 but the engine sounded like it was about to explode. I have never done that again.

    bayoulubejim I actually read that whole thread a few weeks ago and its pretty cool but practically the opposite of what I have planned for my C70. I am actually going to be gearing it back down slightly for more torque/hill climbing ability. Where I am planning to go, I have heard that a bash guard is pretty much a necessity so it will definitely stay. I actually wouldn't mind upgrading to a slightly larger piston/cylinder, but the engine has been so darn reliable for so many miles that I am probably not going to mess with it.

    Today I finalized the bash guard mounting and drilled a hole for oil drain access. Tomorrow it gets painted
    [​IMG]
    #11
  12. slowlane

    slowlane Adventurer

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    chazbird I love S90's. I used to own a 1965 rotary shift S90 that I bought in pieces. That little bike would hit 65 mph no problem which is pretty impressive for an almost 50 year old 90cc motorcycle. I miss that little Honda. Yeah my Passport will stay with me until the end.
    #12
  13. slowlane

    slowlane Adventurer

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    Dang! I just looked it up here on the internet and you're right. I must not be recalling the price correctly but I remember it being well over $2399, enough that I wouldn't even consider it. This was a few years ago when they had just come out and gas was really high so everyone was trying to snap up those little scooters at any price. I can't remember how many times people wanted to buy mine. I knew that SYM built some Cubs for Honda but I doubt any of those were sold in the US.
    #13
  14. chazbird

    chazbird Long timer

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    S90's go "really fast" with a skinny 13 year old on them (way back when). Not so fast these days!
    My C70 will top out at 40, and its screaming. Its perfectly tuned, good compression, etc. I have no need to go faster but I wonder how people consistently get higher mph? I will admit the Symba is a much better bike than the C70, by far. And its better than a Lifan C70 conversion I've ridden too. While the Symba (purchased new for $1888) resides next to a C70 and a BV250, none of them get exceptional miles piled on them. Will it last as long as my C70 has? I don't know, I may not live that long.
    #14
  15. Jacl-Kampuchea

    Jacl-Kampuchea Booze Merchant

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    I love it.

    You could go up to 125cc without many complications, but why bother?

    My 50 will stay a 50 for a while. If I do decide to go bigger a 100cc kit will do 65mph while screaming. . .
    #15
  16. MacNoob

    MacNoob piney fresh

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    Add one tooth on front sprocket makes a difference.
    #16
  17. chazbird

    chazbird Long timer

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    Will this sprocket change change the high-g near neck snapping initial acceleration? Will I have to paddle away from stop lights?

    Also, I have a fair amount of hills where I ride....often I realize I need to chug along in 1st year watching the day go by.
    #17
  18. MacNoob

    MacNoob piney fresh

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    Pretty flat here. Acceleration away from a stop is still ok. But I can't tell you how well it will work on hills. There is an excellent Yahoo group for the C70.
    #18
  19. slowlane

    slowlane Adventurer

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    This C70 is currently running the 15 tooth (one up from stock) front sprocket. It was a very early addition I made to it. The bike takes off from a stop light just fine. I am going back to the 14 and might take a 13 along as well because I'll need the extra torque for my trip. One thing I would for sure recommend that you avoid is switching up the front sprocket and getting a larger rear tire together. I once put a 2.75-17 trails tire on my C70 instead of the stock 2.50 and it killed what little pep it had. For a larger tire I would stay with the 14 tooth.

    Jacl-Kampuchea glad you like my little project.

    chazbird thats cool that the Symbas seem to be good little bikes. I will admit there are a few things that I am not fond of with the C70's. The Symba's telescoping front suspension must be worlds better than the leading link of the C70, and the Honda's rear fender narrows down at the front, causing it to full of mud way to easy. I am glad that the SYM came down in price significantly. Who knows I probably could have talked the dealer down to a more reasonable cost back then.
    #19
  20. slowlane

    slowlane Adventurer

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    The new rear shocks came today and I couldn't resist trying them on.
    [​IMG]
    #20