CT-90 help

Discussion in 'Battle Scooters' started by sidnito, Apr 12, 2012.

  1. sidnito

    sidnito n00b

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    hey, i am new to this forum and really glad to be a part of this community! I just got a 1970 Ct-90 and having some start-up trouble. i replaced the spark plug-got some good blue sparks. i also charged the battery and got a bright green neutral light, headlight works on the hibeam mode, and horn works. i took out the carb and sprayed it down with crab cleaner, but didnt know how to clean orfices. i am just stuck on what to do, supposely it isnt a hard bike to work on and the owner used it two monthes ago. we also replaced the lines that feed the carb fuel, so that's good. it just tries to start but wont fully engage. any tips or advice is greatly appreciated. the owner suggested cleaning the carb orfices, so i guess that will be needed. i am really eager to this up and running, i got it last weekend for my brithday, so im really excited.
    #1
  2. PinkSteel

    PinkSteel Been here awhile

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    I had the same issues with a barn-find '79 CT90 I bought a few years ago. There's old, dried gas deposits and crud in your carb jets. You need to open it up, remove the jets, and clean them with the finest wire and compressed air, until you can see thru them. I think there's the two jets and an emulsion tube.

    I wound up doing this twice, because the first time I missed seeing the emulsion tube...which has tiny holes that clog very easily. Once that was clean, the Trail 90 started and ran, and with the carb adjusted, finally ran really well.

    And, if your tires are old, replace them, even if they still have tread left. They'll be slippery and hard...setting you up for a fall.

    My other advice would be to join the Yahoo Group for the CT90. But be warned...those guys love to wrench and talk about their bikes, so a simple question might start a thread that goes on for days. Great database and files that should address any CT90 issues you'll ever have.
    #2
  3. Seth S

    Seth S Will _____ for _____

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    I was a ct90 owner for a number of years and used to be active on the yahoo group. When I bought my 71 years ago it had a very gunked up carb that took multiple cleanings to get it clean and running properly. The carbs on those bikes are incredibly simple with only a few removable parts. There are only a few air passages in there but they can get clogged and gummed up easily. The easiest option is to buy a new carb for about $80 iirc. However, you might see if the local moto shop has an ultrasonic cleaner that they can clean your parts with. In the end I had to replace the slow jet because it was impossible to clean. www.DRATV.com is a good source for all parts in the small honda line. They have carb rebuild kits with all new jets, seals, and gaskets.
    #3
  4. mattwoods

    mattwoods Adventurer

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    hondatrails.yuku.com

    It's not as large as the yahoo forum, but there's still a wealth of information on there, and there are a few guys on there who know these bikes like the back of their hand.

    In addition to the carb, you might also want to check the points. When I had a hard time starting mine, I pulled the carb apart multiple times and got it to the point where it was immaculate on the inside, and spent hours playing with the adjustment screws. When I finally got around to checking the points, I though "How is this thing still running with such a small gap?"

    Best of luck! They're awesome little bikes.
    #4
  5. sidnito

    sidnito n00b

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    thank you all so much for the tips, i truly appreciate the quick response and detailed information. i will let you all know when i get it running. unfortunaetly it is at my home and i am stationed three hours away, so my dad will have to work on it until i get over.
    #5
  6. snakebit

    snakebit growing old disgracefully

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    I resurrected a c70 that had been sitting for years with gas in it. Cleaned the carb three times, spent $ 20 on gaskets and $12 for Yamalube carb cleaner and finally gave up. Paid $40 for a knockoff carb from dratv.

    With the new carb the bike started on the second kick and was a one kick bike for years after that.
    #6
  7. sidnito

    sidnito n00b

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    thats awesome news! well supposely the carb has been replaced so im hoping it just needs a cleaning!
    #7
  8. PTC

    PTC Turd polisher

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    masshole mofo
    Sell it to me. I will fix it for you.
    #8
  9. gasandasphalt

    gasandasphalt Been here awhile

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    I am having the same problem, CT110,,,the guy I bought it from kicked it twice, started right up.. I got it home kicked it a few times, it started, rode it down the block turnd around and almost didn't make it home...spit and sputer, stopped to never start again????? if I figure it out I will post fix here...​
    #9
  10. mattwoods

    mattwoods Adventurer

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    This sounds like what would happen when I had a hole in my carb float... She would run fine for a while, then she would hesitate, and finally she would refuse to start. I'd turn off the fuel to the carb and let her sit for a while as I scratched my head, I'd pull off the carb and look around inside, and when I put her back together, she'd start right up again. One time I noticed that the carb float sounded like it had something inside of it... it was fuel from a pinhole leak, and when I had the carb apart, I figure that gave the fuel the opportunity to evaporate out of the carb float.

    My bike and I have a very loving but dysfunctional relationship.

    Otherwise, I'd say you might have a weak/not charging battery, but I hear that CT110's can run with a dead battery...
    #10
  11. Speedo66

    Speedo66 Transient

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    I had one too, and I had to leave the gas cap loose for it to run right. I cleaned the vent hole in it, but it wasn't enough, needed the cap loose.

    Ran fine once I figured that out.
    #11
  12. sidnito

    sidnito n00b

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    haha wow that's goofy. should i have the fuel line open when im trying to start it? or just spray carb cleaner in the cleaner and try?
    #12
  13. sidnito

    sidnito n00b

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    well cleaning the carb didnt work, still not startng. so i am going to buy a new carb to be safe. i noticed that the carb i have is this one http://dratv.com/19waca.html but i read that since mine is a k4 (1972) there is this carb http://dratv.com/19ctcafik21.html

    so i guess ill just get the first one since that was on there first, then see what happens this weekend when i swap the carbs out. i read about points, but i am hpoing i dont have to mess with those..i dont know where they are located(is it an easy task?)

    i will keep you guys updated, im hoping a new carb fixes it. thanks for reading my post!
    #13
  14. tjoseph

    tjoseph Long timer

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    If you post your location, there may be someone nearby who will be able to help you in person.
    #14
  15. Speedo66

    Speedo66 Transient

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    #15
  16. topless

    topless Been here awhile

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    I've owned several CT90's and if you have good spark, then it's all in the fuel system. They are simple bikes and easy to work on, but the tiny jets and fuel passages in the carb can be clogged with silt from the fuel tank in a second. You will wear out the screws in the carb trying to keep it running until you just remove the fuel tanks and clean it out. I ended up coating the tank with Por15, and with new fuel line, and inline filter, it ran perfect for 2 years. Now, I haven't even started it for 2 years and with the tank lined, All I have to do is flush the old gas out and it will start because I can't have rust in the fuel system anymore.
    There are places online that you can download a shop manual for free. That makes it even easier.
    #16
  17. mattwoods

    mattwoods Adventurer

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    Points are super easy. On the left side if the engine, near the top, there is a plate held on by two small screws. You pull that off and measure the amount of space between the two contact breaker points. In order to do this, you also need to pull off the plate that sits where the piston and transmission stuff meet, and turn the generator until the points are opened as wide as they'll go.

    And, as pictures are worth a thousand words, you might want to check this out:

    http://ct90-ct110.com/Adjusting-Points.html
    #17
  18. Woodsrat

    Woodsrat Gone ridin'

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    A buddy and I about pulled our hair out (or what little we had left) trying to figure out why his girlfriend's old CT-90 wouldn't rev up. It acted like it was trying to drag a Buick around and had absolutely no power.

    Turned out the spark advance unit was frozen in the retarded position. When you set your points make sure yours is free and well lubed.
    #18