Calling all 4 stroke frame mounters

Discussion in '4-Stroke Engines' started by Ghost0, May 28, 2008.

  1. Ghost0

    Ghost0 Guest

    As I finish up my 2 stroke jackshaft kits, I am ready to move on to designing one for the 4 stroke. For those of you who have, or have seen, multiple 4 stroke kits and mounting plates, how similar are the engine mounting holes between the Honda, Huasheng, Titan, etc? My initial thought is to use the engine mounting holes to mount the bearing plates for the jackshaft but I need to know that they are all the same or at least close. I have one kit that a friend let me borrow. Would like to know how similar it is to the rest.

    Attached Files:

  2. i have honda 50 cc and grubee stage 2.0 kit

    i think other engines were designed according to honda engine.

    i think honda engine is original and all others are imitations of it.

    so i think they could be almost identical.

    the engine bottom has 4 holes that uses Metric bolts i don't remember the

    exact size of the bolts but i think i was something like M6.00 or something.

    i don't know exact dimension for holes position

    i would like to have jackshaft kit for my bike so i can use different gears:smile:

    by the way the gearbox that is on your picture isn't same as mine.
    Last edited by a moderator: May 29, 2008
  3. greguk

    greguk Member

    They are all just to be M6 but engine thread just to be 1.0 pitch (that's make them harder to unscrew by vibration - normal bolts have it 1.25.
    That's not easy to find them - take them hardened or at last stainless steel A2 grade (A4 is to weak).
  4. loquin

    loquin Active Member

    Both the mitsubishi TLE series, and the Honda GX25/35 are mounted using the 4 bolts around the clutch.
  5. HoughMade

    HoughMade Guest

    I have the Honda and Grubee Skyhawk II as well. I believe that the 4 holes around the PTO that mount the gearbox are in the same position on the Honda and clones. I know the Grubee gearbox fits both the Honda and clones the same.

    My question would be whether a plate between the gearbox and engine would cause problems in the gearbox with the length of the PTO.
  6. loquin

    loquin Active Member

    I wouldn't think that an 8th inch or so would cause any problems. But, rather than slipping something in between the gearbox and motor, what about outside the gearbox, where the washer would go?
  7. Ghost0

    Ghost0 Guest

    I am not talking about the gearbox to motor mounting but the motor to motor mount. Are the mounting holes the same? Will the different in-frame motor mounts work with the different 4 stroke motors?
  8. HoughMade

    HoughMade Guest

    They would be the same between the Huasheng and Honda
  9. be aware that crankset you are going to need has to be "wide" in order to clear the engine's width. when i bought my engine kit i came with wide crankset.
  10. Ghost0

    Ghost0 Guest

    Good to know, what exactly do you mean by wide? What is the distance from the center of your frame to the inside of the crank?
  11. HoughMade

    HoughMade Guest

    It isn't really germane to Ghost0's issue- and for that I apologize, but I had the wide crank mounted, but given how low a mounted the seat, I ended up with my knee in my chest- I actually mounted a short crank and that works perfectly because the crank in now under, rather than next to, the pieces that make the Honda/Grubee combo wide.

    To make it more germane to the topic, in addition to the wide one piece crank that comes standard with the Grubee, it seems the Hoot kit (pictured in the OP) comes standard with a 2 crank arms for a 3 piece crank.

    Ghost0- I've seen your 2 stroke setup- great work! But if you keep the jackshaft assembly inside the outer side of the gearbox, you should not have pedal interference. I would think, however, that your setup would require 3 piece crank due to the front freewheel. Is this accurate?
  12. Ghost0

    Ghost0 Guest

    Yes, the system would require the 3 piece crank set up for the front freewheel but the possibility exists to shorten the cranks as you suggest. I will attempt to throw the 4 stroke kit I have on one of the bikes I have to see what the fit issues would be in relation to the cranks. The problem is the only spare bike I have is an extremely small diamond frame so it isn't very representative of what others might use.

    Thanks all for the information. I believe my question has been answered and that most of the 4 stroke engine mounting holes have the same pattern.
  13. ocscully

    ocscully Member

    crank width for 4-stroke frame mount

    The Honda with its gear box I believe is in the 9.5-10in. wide and I believe that it does not sit perfectly centered in the frame. So I would think that you are looking for 5.5-6in. from the centerline of the frame to the back side of the crank arm at the pedal attachment point.

  14. blacktop_sailor

    blacktop_sailor New Member

    I'm very interested in how this can be accomplished.
    It should be easy to make use of the motor mount plate for securing the jackshaft mounting system.

    However, one major issue you'll run into, is the different positions of the output shaft from the different gearboxes will require a different mount for each gearbox.

    Example: The Hoot gearbox like the one pictured above, will have a different output shaft position than a Grubee gearbox would.
    But the orientation should be the same, so the shaft could be the same part, with just a different mounting plate.

    I don't know if the different gearboxes have different output ratios, but since they use similar rear sprockets, one would logically assume the ratios are close enough to not be an issue.

    I'm wishing you godspeed and good luck with this, as it would benefit me directly. :D
  15. Ghost0

    Ghost0 Guest

    You do make a good point but one that I have already thought of. As long as the mounting plate can be adjusted fore and aft there should be no problem adjusting the jackshaft chain for the different gearboxes.
  16. Irish John

    Irish John Guest

    The engine mounting holes are the same for the Honda and Huangwheng but don't know about the Titan cos it's a rear mount. Where would the jack shaft fit on a frame mounted 4-stroke? Is the jack shaft to transfer the drive sprocket to the right hand side so you can run it on a geared hub?
  17. Happyzeds

    Happyzeds New Member

  18. Ghost0

    Ghost0 Guest

    Yes, the purpose of the jackshaft is to be able to use the gears on the rear cassette. You can see how this was done for the 2 stroke kits here.

    The Chopper Happyzeds mentioned makes it too easy as there are no pedal issues because the pedals are so far in front of the motor. No problems with that application.