Skyhawk frame - 4 stroke- 4G gearbox - Shift Kit - 3 speed hub.

Discussion in 'Photos & Bicycle Builds' started by Barry, Aug 6, 2012.

  1. Barry

    Barry Member

    Hello All,
    After MUCH sweat and lots of help from many of you on this forum (especially Aleman), Blackjack is basically finished.
    I took progressive pics along the way showing some pitfalls with the clutch/gearbox, etc that I will happily share with anyone interested.
    I'm now thinking about a mini sidecar project to haul cargo.

    Blackjack4s.jpg Blackjack3s.jpg Blackjack2s.jpg Day One s.jpg

  2. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Very nice looking bike!
  3. The_Aleman

    The_Aleman Active Member

    Wow, she's a beaut! Love the motor mount paint job and in-frame tank. What are you doing for brakes? You might want to consider a drum brake for front wheel.

    You may also find that you need a spring-loaded idler on the outer jackshaft chain. I have a non-sprung idler right now, working on something that's spring-loaded.
  4. Barry

    Barry Member

    Thanks Aleman!
    Yes, there is a new drum brake front wheel on the horizon. My piggy bank has been running low, this build was EXPENSIVE. My JB Weld job on the one-way bearing (gearbox)let loose at the 30 mile mark, I've another ordered up which will be really welded once it comes in. Also been having issues with the crank to rear hub chain streching a lot. On the bright side, the gearing is perfect for me. I get 12 mph in first, 22 in second and 26 in third.
    Thanks again
  5. wjohnson

    wjohnson New Member

    Sweet! I gotta get me one of those
  6. The_Aleman

    The_Aleman Active Member

    That's good, as quick as your bike can accelerate, you definitely need good brakes! :D I had problems with my main chain getting loose, too, I had to install a spring-loaded idler. I found one for $30 made by Kore, called a Chain Reactor, but I believe it's out of production now. You may be able to find one online if you look around. It was well worth it, I've had zero chain issues on that chain since installing the tensioner. The outer jackshaft still needs a spring-loaded idler tho, here's a pic of both of em:


    Chains will stretch and wear rather quickly on setups like ours, I have more miles on my current chains than I've ever put on chains with my bike. 1100 miles on main chain, 900 on the black halflink chains. I usually replace them between 500 and 750 miles. They are really worn out, as is my jackshaft bearings, but I'm waiting on new sprockets before I redo the motormount and chains. Be careful that you don't overtension the jackshaft chains, by the way, you will wear out your jackshaft bearings very quickly. Mine have over 5K on them and I should have replaced them a thousand miles ago lol. Another member who built his shifter 4G setup around the same time I did estimated he got about 1500 miles out of his jackshaft bearings before they wore out. He was tightening them too much with a home-made non-sprung tensioner. I'm unable to utilize the SBP chain adjuster that's built into the motor mount because my frame is too small - I don't have the clearance. Hence, my jackshaft chains are always a little loose, but I guess that works out okay in the end.
  7. Max-M

    Max-M Member

    That is one stunning build. Beautiful. Bravo!
  8. determined

    determined Member

    that is one super nice bike. good job
  9. Zen builder

    Zen builder Member

    Thats a beauty.
  10. SWade

    SWade New Member

    Info for a fellow builder?

    Hi Barry, I was wondering if you'd provide the URL for where you found that seat and headlight? I've got my engine and frame, love the look of a Skyhawk! Have the same front fork, and my frame is at the powder coater right now, that seat is perfect and that light has a classic look. Any help would be greatly appreciated.
  11. KCvale

    KCvale Motorized Bicycle Vendor

    Pretty bike.

    You should at least put the back V-brakes on it since the 3-speed coaster brake won't function.

    I ran the same setup on my GT2 build, your chain is getting loose because the axle is getting pulled forward.

    One option is to put a bolt and nut through the dropout in front of the axle to keep it in place, or just use an axle tug on it.

  12. Barry

    Barry Member