GEBE custom drive gear

Discussion in 'Rack Mounted Engines' started by zack, Sep 10, 2008.

  1. zack

    zack New Member

    I am riding a GEBE 35cc Robin/Subaru. I am happy with the performance of a single speed. However, I want more top speed. How can I obtain/make a 16,17, or even a 18 tooth drive gear? From what I have read it must be custom machined. Where can I obtain a gear that will allow for machining to fit the 5/16-24 bore and thread?

  2. DetonatorTuning

    DetonatorTuning Active Member

  3. zack

    zack New Member

    Hi DT. I read where you have had experience in doing just what I want to. Thanks for the link. It is very comprehensive to the point of me being not sure which of the many gears will work. . Which gear (part number) did you find accepts machining? Any problems with machining?
  4. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    What gear are you running now?

    I doubt if a 17 or 18 tooth will work with your 1.6 HP motor
    The 16 tooth may be too high as well

    Do you weigh 100 lbs?

    Try it, let us know
    Last edited: Sep 10, 2008
  5. zack

    zack New Member

    I am using the 13 tooth gear. The top speed is 29 mph. If I pedal I can get to 32 mph. At this point the engine is at max redline. I weigh 200 lbs. I am of the feeling that I can pedal and reach a higher top speed if max redline is not reached.
  6. DetonatorTuning

    DetonatorTuning Active Member

    as Forbisher suggests you may be in over the capacity of that engine.

    A 6A25M015DF0906 is the 15T example in all alum. / 2 flanges.

    16-18T are available too. i could only use the 15T with my GP460 on drag strip flat road, little headwind.

    good luck,
  7. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Try the 14 tooth. I think that is the highest your engine and weight will pull

    DT's GP 460 had 5+HP yours has 1.6 HP and he weighs less than you
  8. zack

    zack New Member

    Thanks for the gear part number. Will aluminum wear out quickly? I understand that GEBE uses hardened steel gears.

    Running out of HP is a concern, however, I am of the feeling (perhaps over exuberant) that I will be able to maintain a 32 mph speed at 6750 RPM while pedaling. I have calculated that at 25 mph the engine is at 6750 rpm. Therefore a 17 tooth should put me there (32 mph) at 6750 rpm. The question remains--will I be able to reach that desired parameter? Do you have a gear that I may be able to use/borrow to determine real application result?
  9. s_beaudry

    s_beaudry Member

    Steve, out of curiousity I went to the site and can not find that part # 6A25M015DF0906

    I am very interested in seeing this, could you recheck this?

    Thank you, Steve
  10. DetonatorTuning

    DetonatorTuning Active Member

    on home page
    click on "products"

    click "timing belts and pulleys"

    on the far right side
    click on "metal timing pulleys - meteric"

    click 5mm HTD
    click 15 grooves
    click 9mm width

    2 pieces should come up, one with flanges, one without.

    Last edited: Sep 10, 2008
  11. DetonatorTuning

    DetonatorTuning Active Member

    did that work for you ?

  12. DetonatorTuning

    DetonatorTuning Active Member

  13. s_beaudry

    s_beaudry Member


    Yes, worked perfectly...

    I do not have a GEBE setup as of yet, but digging into this, the HD belt GEBE uses has a 5mm pitch and is 9mm wide? This is the same as thier drive ring?


  14. DetonatorTuning

    DetonatorTuning Active Member

    yep, 5mm HTD pitch, 9mm width. i didn't run these for long enough to be able to estimate wear, but there was none visible at the time.

  15. zack

    zack New Member

    Thanks DT- I am encouraged by the fact that I can pedal and hit speeds of 32mph top speed with the 13 tooth gear. While I have a secondary interest in a top speed of 35-37, my main goal is to be able to cruise at 32mph at 6750rpm while pedaling. (hence the 17 tooth gear) Since I am able to reach that speed already it seems plausible. In any event I am on my way to order a couple of gears and then on to a machine shop. Is there anything I may need to know about the machining process, or anything else?

    Have you ever ordered a longer drive belt? Do you have a web link and part number?
  16. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    Why do you want a longer drive belt?
    How much longer?

    GEBE has an exclusive on the HTD Gates belt that they sell

    I doubt if anyone has ever ordered a longer belt because the
    standard belt should work with the 16 tooth sprocket
    Probably a 17 as well

    Please let us know if the 35 cc R/S will pull any of those gears.
    I have my doubts as it is a huge jump from a 13 tooth to 17
  17. zack

    zack New Member

    My GEBE belt is nearly maxed on the length already (as far as slipping on and off.) There may be enough slack if i insert the gear and belt at the same time. I may have to elongate the bracket slots at the axle. I am cautiously optimistic on the power available to achieve my cruise speed. The loss of acceleration and higher speed of complete clutch engagement may be undesirable though. I will keep everyone posted on my endeavor.
  18. heathyoung

    heathyoung Member

    I have a 16 tooth on a 31cc 4 stroke, which is under 1 hp.

    Does 40kph (25mph) easily, 50kph (31mph) with pedalling, and 60 (38mph) down a small hill.

    Mind you, it does struggle up even smallish hills... Its way oversized for a small motor, but its still a bicycle :)
  19. sabrewalt

    sabrewalt Guest

    GEBE Speed

    Gents, I own two GEBE's. One stock RS35, and one Tanaka 40 with the performance carb and expansion chamber and the highway gear. I love the RS35 because it has a gentle sound and is plenty fast for putting around the local area and I love pulling into a gas station and filling up for 40 cents.

    The Tanaka with that expansion chamber is loud obnoxious, whiny, annoys the **** out of the neighbors, makes babies cry and dogs howl and and absolutly kicks the RS35's *** in both hill climbing torque and top speed. It also sucks gas at a much greater rate. I LOVE IT. My son (military) LOVES it.

    Just a thought but if your trying to get some more speed, I'd consider going 2 stroke... This has been covered before but before you go nuts on new gears you might want to try this first.
  20. DetonatorTuning

    DetonatorTuning Active Member

    there's no trick to drilling and tapping the gears ( ibought the metric ones, they have a 6mm hole in them and you barely take anymore out to get them ready for the 5/16x24 die.

    you can do it at home with a drill press IF you have a clamp to be certain they are perfectly flat and the hole goes straight )

    there are NO longer belts, sorry. i always removed the gear when i was messing with the belt, forcing them in and out over the flange COULD damage them even slightly.

    there are other belts and gears they just aren't compatable with the GEBE drivering.