New shift kit problems for custom built bike

Discussion in '2 Stroke Bicycle Engines & Kits' started by Sitherus, Aug 27, 2017.

  1. Sitherus

    Sitherus New Member

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    so I gave up on my old shift kit and bought a SBP shift kit. I got it installed and mostly running in one day. I'm having since chain problems I could use some help with.
    First I should say that I have a shimano rear derailleur and 6 gears with a 7 speed friction thumb shifter.

    First problem, when I go to start the bike by pedal starting it, it won't start all the way I start to pedal,I get up to around 5mph, let go of the clutch, and you hear the engine try to start them die immediately.

    Second problem, I kick start it I get it going about 5mph let go of the clutch and it goes, I mande it really goes, but then the chain is bouncing on the derailleur side so much that 15 seconds later the chain gets bunched up and the bike stops dead. I can no longer pedal.

    I live on a 35° hill with 10" speed bumps every .05 miles and after that it's a straight down 50° hill. I have to have this thing running amazing and have trust that I won't be carrying a 250 pound bike back up if I decide to leave. This bikes gas tank is too wide to put on a bike rack on my car like I did all my other builds and if I throw it in the trunk it will leak gas everywhere. I own an acura rsx and is lowered so no hitch, or motorcycle carriers.

     
  2. Sitherus

    Sitherus New Member

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  3. crassius

    crassius Well-Known Member

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    seems I've seen a lot of threads from years ago about adding some chain guides and tightening derailers
     
  4. Sitherus

    Sitherus New Member

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    Chain guards where? And how do I tighten a derailleur? Do I just remove chain links?
     
  5. crassius

    crassius Well-Known Member

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    that was chain guides, not guards - do a search - there was a lot of discussion about chain bounce and how to stop it
     
  6. Sitherus

    Sitherus New Member

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    Can you provide me with a link. I did research before posting and I just did another quick search. I keep finding one that tells of chain bounce in rough road's and a triangle mechanism that fixes it but the link he provides take me to a page with expired images. I sort of understand the logic just not how to implement it. I installed a DIY chain guide today which helps on the bottom but the top still bounces wildly.
     
  7. Sitherus

    Sitherus New Member

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    1503952441587773372863.jpg
    Chain bottom guide
     
  8. crassius

    crassius Well-Known Member

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    was long time ago and I'm way too old to remember things like that - did you try looking at motoredbikes.com?
     
  9. 5-7HEAVEN

    5-7HEAVEN Well-Known Member

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    Let's tackle the easy problems first.

    First, get a 6-speed shifter for your 6-gear cassette.
    That might be why your shifter is shifting past 6th gear.

    Then adjust your derailleur so that
    it doesn't shift past 6th gear.

    Put your bike in 1st gear.
    determine how many more links you need to
    remove from the chain.

    Leave just enough links so that
    the chain can climb onto 1st gear.

    Make sure it won't shift past 1st gear and
    into the wheel spokes.

    If you're worried about that, install a metal guard between
    the cassette and wheel hub.

    Measure from the inside sprocket to the
    center of the seat tube.

    Try adjusting it to a 50mm distance.

    Get the SBP JumpStop.
    Basically it's a chain guide that
    helps prevent the chain from
    jumping off the sprocket towards the inside.

    The JumpStop won't prevent the chain from
    jumping towards the outside of the sprocket.

    If you're using nuts and lock washers to hold
    the chain ring sprocket assembly together,
    try not to have any threads sticking out past the 5 nuts.

    Use M5 all thread studs to assemble your
    sprockets and freewheel, not M5 bolts.

    That way, when you need to remove
    the outer or inner sprocket, you don't need to
    take apart the entire assembly.

    Use Nylox nuts on the inside of the small sprocket.
    They're rounded off.
    That way, if and when the chain jumps off
    on the inside, the links won't have anything to
    grab onto and annihilate the bike chain
    and derailleur.

    I've used the JumpStart with moderate success.

    However, on my twin-engine build,
    I'm using two 4.5" stainless steel discs
    as chain guides/guards.
    They'll "sandwich" my 24t drive sprocket
    and definitely prevent chain jump.
     

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