KC's GT1 build with tips.

Discussion in 'Motorized Cruiser Bicycles' started by KCvale, Jul 5, 2010.

  1. KCvale

    KCvale Active Member

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    Other than a couple of gripes like the drum brake being virtually useless, the dual rear wheel brake lever uses a fixed position and not a teeter-totter for varied force, and everything already mounted on the handlebars when it all has to come back off....

    I love this bike!

    [​IMG]

    [​IMG]

    48cc Black Grubee Skyhawk GT-2B motor, port matched.
    Upgraded wiring with Keylock ignition.
    Upgraded foam racing grips and automotive gas line.
    No chain tensioner.
    Everything else came on the bike.

    Tips:

    Motor and Chain:
    This bike is a breeze to chain match so you don't need a tensioner.
    1. Set the motor in place leaning slightly forward and tweak down the seat post back clamp.

    2. Your back wheel should come sitting true and your pedal chain firm.
    Loosen the wheel nuts and brake nuts and then back off each "holding clamp" nut one full turn so the wheel can move forward to loosen the pedal chain.

    3. Remove the motor gear cover and spark plug, then thread your chain through using the plug wrench on the gear nut until the top side of the chain sits on the top of the rear sprocket.

    4. Wrap the bottom portion of the chain up and around the rear sprocket with as little slack as possible so it meets the other end on the sprocket.
    You will find that the chain is 1/2 a link off.
    Break your chain back 1 link and then put on a 1/2 link.
    Put the chain back on with the master link and it should look like this.

    [​IMG]

    Note that those link parts retaining sides face out, and the solid side of the master link clip points forward in the direction of travel.

    5. Now loosen up the seat post motor mount nuts and slip a shim between the motor and mounting block (not between the block and frame) until the drive chain is very firm, you will need ~3mm of shim.
    I just used what I have around, a dust cover plate for a PC case slot folded in half with some cardboard shims in the middle.

    [​IMG]

    Once the the drive chain is firm tighten down both front and back motor mounts.
    You can take the new slack back out by tightening the rear wheel "holding clamp" nuts equal distances until the chains firm up.

    You want the motor chain a little tighter than the pedal chain.
    After you put about 20 miles on it tighten them again until the drive chain is perfect, if there is to be slack after initial seating you want it on the seldom used pedal side, just don't get the drive chain too tight or you will wear the motor bearings. Besides, the rear hub mounted sprocket already comes attached in perfect alignment, you get chain jump with a little slack.

    I will do the Handlebar Controls in another post, it has pics too ;-}
     
  2. KCvale

    KCvale Active Member

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    Handlebar Controls:
    You have to take the left grip off to get the clutch lever on, and the throttle off to put in the throttle cable from your carb so it is a great time to dump those crap hard plastic grips.

    The problem is, the throttle side grip is fatter because it has to fit over the throttle barrel.

    [​IMG]

    That's OK, save some time and just use a knife to cut the left side grip off, take the throttle off and pull the throttle barrel out and cut it's grip off too.

    You can get foam racing grips at most bike store for ~$7 and they work and feel great!

    For the left side, I found mounting the clutch between the front brake lever pointing down and the front brake lever level with the right side rear brake lever to be the best.

    [​IMG]

    I actually prefer my levers facing downward for where I put my handlebars and ride, but with 2 levers on one side matching the brakes and leaving room to operate the clutch and lock does fine, and the pre-drilled hole for the metal throttle mount is straight out forward anyway.

    [​IMG]

    While you have the throttle apart to put the cable in, put some grease on the bare handlebar and inside the metal throttle housing and be SURE to not tighten it back up until the little stay prong fits in the pre-drilled handlebar hole and the throttle is turned open enough so you don't tighten in down on or before the throttle stop.
    Fill that with a little grease too, we don't want a sticky throttle ;-}

    Kill Button Warning!
    Unlike the regular kit throttle kill buttons, this kit's metal mount actually grounds the black wire on the kill button!
    If you mix up the wires and hook the black ground to your hot your bike won't run.
    Unlikely if use it's frame mount round eyelet lug, but if you re-do your wiring like I do yo ened to pay attention to that.

    I will do back brake adjustment and more electrical soon, and I hope that helps some of you build a better bike.
     
  3. KCvale

    KCvale Active Member

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    Wiring:

    As mentioned above, BEWARE THE GT1 KILL BUTTON!.
    The black wire is grounded to the frame via the metal mount to the handlebars.
    Mix up polarity and your bike won't run without keeping the kill button pushed in.

    "Standard Procedure" says to ground the black wire with it's eyelet to the frame, and then run the red wire all the way to down to the motors White Main Magneto Wire.

    Sure it works, but you don't need to do it that way.

    I have yet to put the the raw unregulated AC from the magneto to use so I clip off the connector and cap it off.
    You can kill the motor by simply shorting out the Blue ignition wire.

    That being the case you only need the motors blue and black wires up to the CDI ignition module, and then wire your kill button to it.

    I like a clean look and just splicing the stock electrical systems wiring is in a word, ugly.

    What I do is add a little box to the CDI unit and replace all the wiring with heavy duty double shielded 18 gauge wire and connectors, and then since I had room in the little hobby box I add an ignition keylock.

    [​IMG]

    [​IMG]

    Radio Shack has little black plastic hobby boxes you can cut down for about $7.
    For the switch you can use the "Keyboard Lock" keyswitch for an old "IBM Compatible" PC case, but to buy a single good keyswitch small enough if you can is about $25.

    The wire, well I all I could find I liked was 100' spool at 50 cents a foot.
    The crimp on connectors are cheap though, most any hardware store has them, and then just a little shrink wrap tube for each end to clean up the connections.

    I just went ahead and bought enough parts in bulk to make 50 of them, but I can part with a dozen or so "bag of parts" delivered for $17.95 if you want.
    All the rest I am keeping for my own builds ;-}
     
  4. chainmaker

    chainmaker New Member

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    Very nice.. I checked out Your website I like how You offer the 3 versions of it. Good luck hope You sell a bunch. I also had to post so when Im ready to buy one I can find the listing.

    Cheers
    Chainmaker
     
  5. oldsurfer

    oldsurfer New Member

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    I Have The Same Rear Hub Setup On My New Build..is There Any Way To Get A Good Result Out Of The Rear Drum Break ..any Secrets To Adjustiong It
     
  6. city of angels

    city of angels New Member

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    yes i have the front fork set up on my trike from the gt 1 i like it because it give you two options for brake placement nice build once i get some money together i will be buying one of you kit ignitions
     

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  7. KCvale

    KCvale Active Member

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    I had no joy getting the drum brake to work on the dual pull lever with the V-brake and ran out of time, the customer picked it up.

    But, I'll tell you what I was going to try...

    Swapping the front brake cable on the left lever with the drum brake cable on the dual pull right lever.

    It is easier to match up pull tension on a pair of V-brakes than a V and a drum, especially the dual pulls without a tetter-totter swivel in them like I used on my Suede shifter bike, but it has a V front and a side pull back I added.

    I love having both front and rear brakes with just my right hand.
    I figure with the GT1's drum on the left lever out of the way, you pull the cable tight on the cable holding nut on it's connection and tighten it more if needed from the single left handlebar lever.

    With the travel of single lever all to the drum I think you should be able to make it least a sort of an emergency brake but mostly rely on the dual pull front/rear right hand brake lever.

    Just a thought that might help ;-}
     
  8. KCvale

    KCvale Active Member

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    Nice trike, looks like you could haul a lot with it.
    As far a front shocks go I'm sold on them, that and foam grips.
    Those hard plastic kit grips are miserable even with front shocks.
     
  9. city of angels

    city of angels New Member

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    yes thank you i like it when i go to the store and do my grocery shooping yes just got neon lighting kit put on them since people dont know how to drive here in tucson question if i get the igtion module do i still have to pedal the bike
     
  10. KCvale

    KCvale Active Member

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    If you mean the motor won't start without turning on the key, ya, but you can still pedal it.
    http://motorbicycling.com/showthread.php?t=19737

    But if you mean will it start your motor on it's own, no.

    If you have poor ignition spark as a loss of power cause and then have to pedal with a load, then yes, the better wiring really helps that specific thing.

    It's main purpose is to add a keyswitch directly to the your CDI to disable ignition.
    I just went ahead and added a much better wiring system too because, well, I could ;-}
     
  11. robertgibbs

    robertgibbs New Member

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    hi this is robertgibbs i would like to know where you got the throttle dual brake hook up
     
  12. soup325

    soup325 New Member

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    Nice too see another GT1 setup.

    Did you remove the disc brake on the front? That button is a nasty one. I have replaced mine with a rocker switch.

    Also, did you change the crank, from the one piece?

    The seat change tops it off.

    http://motorbicycling.com/f41/gt1-skyhawk-48cc-28190.html
     
  13. KCvale

    KCvale Active Member

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    That single piece throttle & dual brake lever is junk.
    It came on the GT1 bike and I ended up replacing it.

    I now use the kits throttle, and the self adjusting dual-pull 'teeter-totter' brake lever from Sick Bike Parts LLC - Performance parts for your motorized bicycle for $10 if memory serves.

    [​IMG]

    You can see how the 'teeter-totter' arm moves to adjust for the slack in the cables and different throw lengths to apply equal power to each brake.

    For example the bike in that pic has a front V brake and a side pull rear brake yet they work great with that lever.
     
    #13 KCvale, Mar 29, 2011
    Last edited: Mar 29, 2011

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