2-cycle Specialized RockHopper Comp FS

Discussion in 'Photos & Bicycle Builds' started by mouchyn, Sep 21, 2008.

  1. mouchyn

    mouchyn New Member

    Bike: Specialized RockHopper Comp FS circa 1999

    Engine: Chinese 2-cycle engine kit, seller claims 38cc. The kit did not include original manufactruer documentation, only a poorly-written installation guide. The language in that packet is what I would expect from a child. Kit included the usual: engine w/ carb, exhaust pipe w/ baffle, fuel tank, grips/killswitch/throttle, clutch lever and cable, chain, idler, chain guard, drive gear, rag joints, and necessary hardware

    Upgrades and Enhancements:


    -Blue motorcycle-grade fuel line
    -Yellow NGK 8.8mm spark plug wire
    -Black NGK plug connector
    -NGK B7HS spark plug
    -Repositioned Clutch arm - significantly reduced lever effort and smoothness
    -Bored (slightly) engine mounts to fit wider Specialized frame
    -Flat engine mounts - Cut from left-over Harley parts
    -Replaced engine mount studs/nuts with Honda automotive bolts (more left-overs)
    -Replaced exhaust studs/nuts with Honda exhaust-grade bolts
    -Wrapped bike frame with think PVC pipe-wrap at all metal contact points - This has done wonders for longevity and reliability
    -Nearly every bolt/nut/screw on the bike has some loc-tite - I check everything weekly, but nothing has loosened up since application of the thread locker. Even the exhaust and engine mount bolts are still tight!
    -Ring terminal secured to water-bottle mounting hole (kill switch ground)
    -Semi-neatly taped and secured cables and wiring to the frame
    -Replaced Exhaust pipe gasket - There are absolutely no leaks where the exhaust pipe meets the engine, now. Dad traced and cut 10 more from a roll of exhaust gasket material for me (Thanks Dad!). The gasket works great until you remove the exhaust pipe. It totally cracks and falls apart. These gaskets are definitely one-time-use only.
    -Baffle - Galvanized pipe fittings modified to achieve an hourglass shape. Several holes were drilled in the 4-inch pipe segment inside. The original baffle blew out on the road and was destroyed by a car. The screws didn't come loose, but the bottom half of the screw-hole in the exhaust can broke and the whole assembly slid right out at 30mph. Until a final design is reached, the baffle is held in with a wire coat hanger wrapped around the top of the can. Although the final design will likely be welded in the exhaust can, the wire hanger rig has been more secure than the original design.


    -26" Ritchey off-center wheels
    -Ritchey wheel hubs, crank hub, steering hub
    -Cateye Opticube 3-LED Headlight
    -Cateye 3-LED Red tail light
    -Sunlite Black Aluminum Luggage rack, Spring-loaded cargo arm, Saddle bag friendly
    -Dual-brake lever, AWESOME when the brake bias is set properly
    -AirLift wide-saddle, pressure/firmness is adjustable
    -Suspension seat-post, really smoothes out the urban landscape while commuting


  2. Yup seen those little buggers

    My friend has the 48cc from this older distributer and it was Bigger than this one. That was the smallest Ive seen is this model. My friend had opted for the Centrifugal model. If you took the carb apart youd probably see Brass slide. Like wise the Engine was cast steel Jugged.
  3. charlie51bc

    charlie51bc New Member

    I've got a 95 Spec frame virtually the same.What did You use for Shims ?under the Chain Tensioner?
  4. are you talking about the engine on the first Question?. For the Rear you can grind a spline surface on the in
    side of the C and it will clamp onto the frame without sliding. If your chainstay is too small of a Diameter that is a different problem moving it closer to the Crank will be putting it on bigger diameter material (same chainstay ie.: Bottom left bar.) Soft or harder metals work like cadmium or lead
    Last edited by a moderator: Feb 14, 2009