Seeking info from our Oz members: belt driven rack mount

Discussion in 'Dealer Reviews' started by Happy Valley, Nov 6, 2008.

  1. Happy Valley

    Happy Valley Active Member

  2. heathyoung

    heathyoung Member

    Look for a thread named "Every time I ride it something breaks". I fixed everything that broke, but I'm looking to sell it as I got a 70cc 2 stroke happytime. Probably also going the SBP shifter kit as well :)

    Without the numerous fixes I have done - they are truly shyte. See below:

    I bought this kit about 4 months ago as a cheap way to get to work - Its a blackstar kit (like the ones advertised for $450) - basically a copy of a Golden Eagle Bicycle Engine kit (link). Its a 4 stroke engine, a copy based on a Honda GX31 - stated power output (written on the side) is 200W, so *technically* its legal (you could claim ignorance), but the engine is really 700W (~1hp) output.

    Once it was run in, with 10W-30 Penrite oil, and running on premium 98 octane, NGK sparkplug and highflow air filter (ie. its current condition) it uses 1 tank of fuel (900cc's - at 1.50 per litre = $1.35) per 60 klms, with the average speed of 45-50Kph on the flat easily. Its great fun on the road, and even more fun to throw on the (supplied) offroad gear, and do some bush bashing!

    I have changed a few things from the original design, due to 'teething problems' I experienced with the kit (now all sorted).

    1) The original design didn't suit a bike with caliper brakes very well, it had to be tilted back so that the belt cleared the brake mounts - The problem with this is that you couldn't fill the fuel tank more than 1/4 full or it would leak in the heat (out the vent on the cap) and you had to hold up the rear of the bike when filling the fuel tank - this has been fixed by making new fuel tank mounts that allow the filler to be on the exhaust side, rather than the intake side. You can fill the tank all the way up at the service station now!

    2) Replaced the supplied bolts that hold the motor to the main frame with longer ones, better lock washers and nylocks after the stock ones came loose and the belt shredded against the mount and snapped (and broke the crappy plastic belt cover).

    2) Replaced the fuel hoses (the rubber one goes hard and cracks, just sucks in air) with silicon TYGON hoses (the best).

    3) Replaced the fuel filter with a smaller one from a whipper snipper as with the old one, and a low tank of fuel, the filter starts sucking air in corners and the engine stumbles/dies.

    4) Changed the sparkplug from a chinese no-name to a genuine NGK CR5HSB after it developed a misfire.

    5) Replaced the carburattor diapraghm + seals with a genuine Walbro WYK rebuild kit to fix a surging/flooding problem.

    6) Applied blue locktite to all the bolts that keep coming loose on the engine ad-nauseum due to vibration.

    7) Replaced the standard 'thin' belt to a thicker one - better for offroad use (11 tooth has much higher torque - broke one of the thin ones with it).

    8) Fitted a highflow air filter - made about 3 kph difference to the top end speed.

    9) The clutch bell is a truly poor design - Made from pitbike components, but the major thing that they didn't do well was to make the centre bolt longer - and put a nylock nut on the end - they welded it to the bell - so you down a hill while accelerating (it will top out at about 72kph) and let go of the accelerator and the clutch pads dont let go - you engine brake, and this snaps the weld, and unscrews the pulley!

    I welded it twice before I gave up on the welding - Drilled through both the bell and the bolt, threaded it with a M4 bolt, used blue locktite on the main bolt and the M4 bolt, and silver soldered the *******. Its not going anywhere now!

    I'm putting my kit on Fleabay with all of these fixes for around $300 - can sell here if you are interested...
  3. Happy Valley

    Happy Valley Active Member

    Hmmmm, thanks for the lengthy review.

    My interest was actually in the drive hardware and mount, already have an engine I'm thinking of using.
  4. heathyoung

    heathyoung Member

    Ah - OK.

    The lower mount (that attaches to the bike) is bulletproof - heavy steel, big welds etc etc. I would strongly recommend that you use solid rather than quick release axles due to the thickness of the metal used - you could use longer skewers, but mine didn't have a hope of fitting.

    Upper mount - solid BUT really only designed for the engine it comes with - mounts to two of the cluch bell threads (upper) and to the base mounts (where the fuel tank bolts to) - the base mounts are NOT standardised. I was going to use a 2HP 49cc 'gokart' engine, but make an upper mount from black nylon (25mm thick or so) and mount it using the 4 clutch bolts - much sturdier.

    You need to make an adjuster into the lower mount so that you can tension the belt - even with lock washers, and nylocks the upper mount will flatten to the lower and lose tension, the vibration will do it.

    Drive ring - 36 spokes, toothed with 10 teeth in 4 quadrants (rather than all the way around like the gebe) so if you try to take off hard from a standstill it will slip. Some 'belt anti-slip' spray works wonders here. Means you don't have to have spoke bending tension so you get zero slip.

    Drive gear - 16 tooth or 11 tooth available from seller - pretty sure GEBE non HDT drivegears fit (same thread pitch and size) but never tried it. Hardened teeth by the looks of it too.

    Belt - There is a thin belt that works OK, but I've snapped 1, they stretch BADLY. The thicker belt is a must for longevity - less slip, less stretch.

    Clutch bell - Stock - very, very bad idea - you MUST get it welded properly, or the stud that holds the gear on (and the gear!) will dissapear to places unknown when you deccelarate hard under engine braking (clutch wont let go until revs drop). Get someone to weld the base again with a tig (not MIG - you need very good penetration in a small area) and the top 'cone' interface, and also if possible, dissasemble the bell assembly, drill through the bell and stud, (below the bearing) and tap a 4mm setscrew into the both of them, loctite it secure. Do NOT underestimate the shearing forces at work here - I've broken 2 welds and sheared a cotter pin. Mine is held in with silver solder at the top, and locktite for the stud, with a 4mm screw through the bell and stud. Its holding now quite well.

    The clutch bell assembly is the achilles heel of the design... That and the engine. (Bleah)

    Heath Young