Newcastle, NSW, Australia

Discussion in 'Introduce Yourself' started by heathyoung, Aug 20, 2008.

  1. heathyoung

    heathyoung Member

    Hey all,
    just getting into motorised bikes - I bought one of those $450 4 stroke GEBE 'knockoffs' from fleabay to fit to a 15 year old Merida mountain bike.

    Its been a bit of an experience - never expect an ebay seller to be exactly upfront about their products... But i'm hoping there are a few more knowledgeable people around that can help iron out the bugs...


  2. Aussie_Glenn

    Aussie_Glenn Member

    Welcome Heath,
    So what are the issues? Got one of those a couple of months back. It's been sitting in the shed waiting for me to get some time to fit it. Be keen to hear of your problems. May be able to help, dunno.

  3. heathyoung

    heathyoung Member

    Well, the seller was less than forthcoming with information as to fitment, it definitly does NOT suit a bike with quick release skewers (changed the rear axle to solid) and the fuel tank sits at an angle such that you cannot fill it up very much - not sure if I did it would leak out the cap? It holds vacuum, but hopefully wont leak.

    It would be good if the motor was able to be tilted so that the tank filler was upwards (as per the tanaka purefire's - but they are a 2 stroke, so they don't have a sump).

    Gearing is also very poor, a 16 tooth gear on the motor means acceleration is poor, with little hill-climbing ability, I'm hoping that the 12 or 13 tooth from Gebe will fit it. It does do an easy 30-35kph, any faster and it gets this awful vibration, not sure where this is coming from, seems to be a harmonic from the belt?

    The stupid cheap throttle doesn't exactly inspire confidence (i'm getting a dual brake lever for the LHS and using the RHS original brake lever as the throttle) but thats not that bad - the choke needs to be on for a lot longer than I expected as well. The kill-switch isn't too bad though, and it isn't too noisy - and the rack mount means I can fit a 7.2A SLA to power the headlights easily as well.

    A Honda GX35 sounds like a bit more fun, but I'll see how far I get with the gearing - the 'sumtingwong' brand belt doesn't inspire confidence either - time to look at a gates catalogue.
  4. cookcamp

    cookcamp New Member

    Hello Heath and Glenn, looks like we all have the same kit. I've had mine fitted to my large frame Mongoose hybrid for about 2 months now, and apart from some rear wheel and brake issues, I have found the kit to be a very effective way of reducing my fuel cost's, particularly to work and back.
    Heath, I found by fitting the mount on the inside of the frame that the straight up position could be achieved, thus retaining full fuel tank usage. Not much vibration to mention, but my motor does seem happiest on the flat between 30 and 45kph.
    I agree with you on the belt, and it's interesting to note that my freind just purchased the same kit and her belts supplied are double the thickness of mine! If you do source a better option, please let me know. Cheers Martin.
  5. Aussie_Glenn

    Aussie_Glenn Member

    Cheers blokes, thanks for the tips. Hope to get to mine in the next week or so. Will let you know how it goes.

  6. heathyoung

    heathyoung Member

    I'm not sure I could mount the motor inside my frame, I'm having trouble visualising this...

    I'll probably design a mount out of aluminium to turn the fuel tank around so the filler is on the high side.

    I've been looking at belts around the place, there are some really good ones that are used for timing belts/power transmission - Farnell list some that are steel belted inside, with a 10mm width and 5mm pitch, they can transmit about 5KW(!!) - very suprising for their size.

    I'll see if the GEBE drive pulleys will fit onto these kits, gearing would probably help with the hill climbing ability - but so would a Honda GX31 (what these engines are a copy of - NLA though) or its replacement the GX35.
  7. cookcamp

    cookcamp New Member

    A slight misunderstanding. The frame that the motor bolts on to, instead of placing this on the outside of the bike frame, as per instructions, and securing with the axle nuts, I've put mine on the inside of the bike frame to allow me any angle to set the motor at.
    If your frame is like mine there may be some obstruction stopping you from placing it in the ideal spot, ie straight up. So this is how I resolved the problem. I also purchased a new heavy duty wheel, with a longer nutted axle and my gear cassette fitted for $100 from the local bike shop, and this has made a great improvement. cheers Martin.
  8. heathyoung

    heathyoung Member

    I see - my brakes foul on the belt if I don't have mine angled back - I found the reason for the vibration at higher speeds - centrifical force throws the belt back against the brakes :(

    I'll probably modify the fuel tank mounts to get the tank turned around I think.
  9. cookcamp

    cookcamp New Member

    Yes Heath I had the same issue with my brakes, so I have removed them for now and am lookig at mounting them differently. And yes I am very aware of only having front brakes atm , which I have adjusted accordingly.
  10. stude13

    stude13 Active Member

    gates produces that belt solely for gebe. the engine can be mounted any way that works because of the oiling system on a r/s engine
  11. heathyoung

    heathyoung Member

    I'm thinking of mounting the fuel tank from the engine elsewhere - I have a 7.2AH SLA in a plastic box on the support rails, so mounting the fuel tank on top of that would work OK, failing that, there are quite a few different fuel tanks available from kart places.

    Not sure how fuel safe the box is though - IP65 Polycarbonate. Hmmm.
    S= Fair resistance, etching after 7 days exposure to reagent , spose thats OK.

    Also found a tacho circuit I might build for interests sake

    Will probably use the killswitch wiring (its across the magneto) as a source for the pulses, optoisolated with a 4N25 or something.
  12. heathyoung

    heathyoung Member

    Took the blackstar kit apart to have a good look at it...

    Some good news and some bad news...

    Good news is - the bolt pattern is a standard 70mm spacing, same as a Honda GX35 - the clutch would fit OK.

    Bad news is - the pulley is very different to the GEBE ones - its threaded onto the shaft, 10mm dia but an odd thread pitch (fine pitch) - but not left hand thread...

    Which means (as far as I know) that the GEBE pulleys wont fit. Farnell do sell aluminium ones, with a centre hole drilled in them - but they don't have a tooth count less than 15 in the 16mm wide version (they do in the 10mm wide, but the pully width makes up for differences in the belt tracking)

    Sigh. Its almost a gebe, but its full of flaws.
  13. quay1962

    quay1962 Guest

  14. Aussie_Glenn

    Aussie_Glenn Member

    OK, started my build and ran into the same problems.

    Replaced QR axle with longer, solid axle. No problems was expecting that.
    Mounted the engine and tried to line everything up and........the drive belt fouls the rear brakes!

    So I think my options are convert to disc brake on the rear (maybe not a bad idea but pricey) or consider alternative mounting options to clear the calipers (include make some alternative mounts)

    I notice the bike on the ebay pictures is a jardtail with linear pull rear brakes like mine. It either has some weird frame geometry, engine is mounted way back (doesn't appear to be).

    Think I'll retire to the shed with a beer or three and ponder options over the weekend and wait for inspiration.

  15. heathyoung

    heathyoung Member

    I turned th tank around on mine, so that the filler is on the exhaust side, and tilted the engine so the belt doesn't touch the brakes.

    It actually went better like this, I think it was suffering some major fuel starvation issues before!
  16. cookcamp

    cookcamp New Member

    Hi Heath, sounds like you sorted your fitting problems out then. I just completed another fitting of the same kit for a friend, and apart from using a spare wheel with axle nuts, have had no issues, the belt even clears the brakes in the straight up position! Cheers Martin.
  17. jlebh1

    jlebh1 Member

    why not just buy the optional bike that the engine fits perfectly with the engine I am thinking of getting one of the blackstar kits there are a few people selling them now but i think i might get one from blackstar direct? are they OK?
  18. heathyoung

    heathyoung Member

    I ended up on-selling the blackstar kit on ebay, there was a LOT of stuff that needed resolving with the design.

    The bike that they have is too small for me - I need an XL frame, I'm 6'3" so a small frame is no good.

    Change the carb diaphragm with a genuine WYK walbro item, replace all of the bolts with good quality with nylocks, use loctite everywhere, get the thicker belt as the thin one stretches BADLY and needs constant adjustment. Use a better sparkplug (NGK) and replace the fuel filter with a whippersnipper unit as the stock unit is big and sucks air when you go around corners too fast.

    The gearing is poor for the engine power too. Also, you will break the weld in the clutch bell if you keep on the power down hills and let off it mid way (engine braking) Its a bugger to stop this from happening so keep it in mind.
    Last edited: Dec 10, 2008