4G Belt Drives have gone down in Price

Discussion in 'General Questions' started by kadude, Feb 1, 2010.

  1. kadude

    kadude New Member

    I noticed that the 4G Belt drive has gone down in Price. Is there any new updates on this kit or is it still considered junk? As I have read the other thread on the 4G.

    For the price of $299? It does seem very attractive. Or should it be avoided?

    Thanks in advance.

  2. arceeguy

    arceeguy Active Member

    I would take the advice in "the other thread" with a large grain of salt, as the original poster pretty much hates anything built in China. Check out his posting history and you decide.

    I may give the 4G a try for $299 since the days of the inexpensive 2 stroke are numbered, and 4 strokes are most likely the future for light transportation. Besides, the engine can be used on other drive systems if it turns out Irish John was right.
  3. Irish John

    Irish John Guest

    I was right about the 4G incidentally and it is a total lemon for all the reasons I stated but I have managed to make it work by adjusting the gear ratio.
    As it is currently made the gearbox doesn't get enough speed but it does put a lot of torque through the 11T freewheel sprocket. They can't handle the increased torque and the users have all had problems with the 11T sprockets failing very quickly. The ratio can be changed by either increasing the size of the small pulley or decreasing the diameter of the second pulley. Increasing the size of the final sprocket isn't an option because the engine casing won't allow room for it. The 4G is too big anyway so it makes sense to replace the second large pulley wheel with a smaller one. Then you get a gearbox that performs really well and, unlike the Mark2 & Mark 3 Grubee GBs it is very quiet.
    This is expensive to do of course but is really necessary if you want it to work at its optimum on a 26" wheel.
    The old Mark2 & Mark 3 GBs are pretty good but are very noisy (although I have found about one in eight is actually very quiet but that must be luck of the draw).
    Don Grube says people shouldn't go too fast and that is why the 4G is like it is but the real reason is that they were never tested properly before production and he was too proud to ask any of several MBc members who have the knowledge and would have helped him get the ratio spot on first time.
    I haven't tried the EZ gearbox but I'd bet it has to work better than the 4G.
    So I'd recommend a noisy Grubee Mark 3 GB or an EZ if you can afford one but the 4G is pretty good if you are prepared to get it partially rebuilt at good tooling workshop and are prepared to pay the cost for that and ride around with short cranks and legs wider apart because it is seriously wide.
    The older Grubee GBs get worn bushings on the primary drive gear and that often requires replacing - sometimes after only 5000 miles but it isn't expensive - the bushings need replaced and the primary gear needs replaced as well but if you have lots of new bushings you will find one to fit a worn primary gear because the bushings vary a bit in diameter and a fatter one will fit a worn primary gear & bell housing very nicely. That is my experience from building and servicing quite a number of Grubee fourstroke kits. I like the old gearboxes and I suffer the horrible whining noise but many of my customers can't stand the GB noise. A good quiet GB certainly has a lot going for it.
    Until I try the EZ I can't really talk about it but I have great expectations of it when it eventually arrives in our neck of the woods.
    The film of it is very nice to watch. If you want my advice buy the EZ but I can't talk about it from experience like I can the others.
    I also spent 4 years working in construction industry in China between 2000 - 2004 and quality is not something I ever managed to get unless we used Hong Kong fabricators or contractors and they cost a lot more.
    Last edited by a moderator: Feb 5, 2010
  4. aero07

    aero07 Member

    Irish John,
    Since you went to all that trouble why not share what your set up
    is now. What gearing did you end up with? Maybe that would help someone else
    down the road.
  5. kadude

    kadude New Member

    Well? I finally bought the kit and runs Great! There were few things I was very unhappy about with the kit..Obviously the lack of good instructions being one of them.

    Also..The lack of pedals was abit of a pain as I later found out for myself that the threading is for Childrens Pedals and not standard Adult size.

    Kit is wide but? Runs nice and smooth..Has alot of Pickup and torque compared to my 2stroke 66cc Skyhawk..

    I can't complain for $299..Well? At least not yet..Time will tell I guess..