ULTIMATE system?

Discussion in 'Frame Mounted Engines' started by pmarkwell, Aug 5, 2008.

  1. pmarkwell

    pmarkwell Member

    Okay, guys. I'm really curious what you guys think about this idea. I think it would work, and would be a very sound conversion. My vision is to have a frame-mounted motor that utilizes BOTH front and rear dérailleurs.

    From what I've been reading, this will be a culmination of many different systems put into one. So here goes:

    We start with any ol' bike.

    I'm thinking a good engine right now is to run the 4 stroke Honda GXH50 (http://www.smallenginewarehouse.com...1+5+8+Keyed+Shaft+Overhead+valve+LOS+7000+RPM)

    Next, we'll use the clutch from Staton (http://www.staton-inc.com/Details.asp?ProductID=3288)

    The gear box and mount will come from the Whopper Stopper (http://www.bicycle-engines.com/49cc-complete-powered-engine-p-156.html)

    Now, instead of running a chain to the rear wheel, we run it directly to the front sprocket that we get from here (http://www.cyclone-usa.com/store.php?crn=203) that utilizes a 14 tooth freewheel sprocket, chain wheel, and crankset.

    Am I missing something here? Why has this not been done yet? I soon have plans for a GEBE/GXH50 build as soon as the motor comes in from Staton. But I would think this might be a better way to go. Any opinions, comments, suggestions would be appreciated.


    Last edited by a moderator: Dec 16, 2015

  2. HoughMade

    HoughMade Guest

    Sounds like a 4 stroke version of the shifter kit from sickbikeparts.com...

    ...which sounds like a good idea to me.
  3. appye

    appye Guest

    Um. I am not following. Hooking the engine directly up to the front sprocket seems like you would be forced to pedal at all times, very fast. Is there some kind of freewheel in there somewhere?
  4. pmarkwell

    pmarkwell Member

    Yes, appye. Cyclone-USA.com sells electric motors that mount directly to the bottom bracket which runs the font sprocket. To combat the situation you're referring to, they've designed a front freewheel/crankset combo so the chain is driven but doesn't spin the crank arms on your bike unless your peddle. At least this is what I understand from their website.

    Oh, the one thing I forgot to add to this system was a chain tensioner, of course, but I'm sure that wouldn't be difficult to do. Also, thinking more about it, I suppose we could use the 3:1 compact Staton gearbox instead since most of the shifting would be done on the bike. I haven't done all the math, so I'm not sure what the best ratio would be.

  5. HoughMade

    HoughMade Guest

    I know that these guys:


    are at least exploring the idea of a 4 stroke kit which addresses your idea nicely. I have the Grubee Skyhawk II (which I prefer to call it) on a Honda- it's great, but gears would make it more greater!
  6. pmarkwell

    pmarkwell Member

    Houghmade, how do you mount your Honda? Did you make a bracket yourself or find one somewhere else? I have limited metalworking ability so it would be nice if I can find one somewhere that fits the GXH50.

  7. ocscully

    ocscully Member

    There may be an issue/problem getting the Staton Clutch to work with the Grubee gearbox? The Clutch bell from the chinese clutch would need to be compatiable with the Staton Clutch. As Hough has already said the guys at Sick Bicycle products are currently working on a system to do exactly what you describe, and they are currently marketing a system for the 2-stroke happy times. The other area that adds problems for such a system for the Honda GXH50 is the overall width of the motor, gearbox, & jackshaft, and getting the crankset to clear and still keep the froun sprockets in the proper chainline?

  8. HoughMade

    HoughMade Guest

    I used the entire Grubee Skyhawk II kit (with my own engine) which includes a mounting plate.
  9. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    There are two different styles of mounting plates for the Honda gx50
    or the Chinese copy of that motor
    One is a short plate that will only fit V style bike frames

    the other is a longer adjustable plate that fits a cruiser style bike

    I have attached a couple of pics of the Grubee kit which show
    the engine mounting plate

    Right now there seem to not be any kits available and it
    will be difficult to just find the mounting plate.

    Last pic shows the plate on a felt cruiser


    Attached Files:

    Last edited: Aug 5, 2008
  10. pmarkwell

    pmarkwell Member

    Thanks for the tips guys. I typed Grubee into google and came across an eBay seller who sells the gearboxes, mounts, 105g spoke wheels, and even hubs with dual freewheel sprockets. Say goodbye to bolt on sprockets! I like what I see from this vendor. I don't know why I haven't seen or heard about some of his stuff from this site.

    You can find him here:

    I've also attached a couple of pics of his sprocket hubs for your convenience.

    I think I'm going to send back my GEBE system and equip myself with a nice Grubee gearbox. Anyone interested in a GEBE with a 78mm clutch mount? I guess I should probably list it in another forum. I'll have to give a little more thought before I commit to anything.


    Attached Files:

  11. HoughMade

    HoughMade Guest

    I would urge you to read these before committing to buy:





    I'm not saying not to buy, but be aware. I bought from him in the past (as you can see from the last link), but according to these above links, I am in the minority.

    Also, be aware of what you are buying- I would never buy the non-adjustable mounting plate because it is a crapshoot with mountain bikes and a no-go for cruisers. Likewise, I personally would not buy the JL Hoot gearbox (looks like an "8" on its side). He advertises the Grubee, but you have to know for sure that is what you are getting.
  12. pmarkwell

    pmarkwell Member

    Wow! Thanks for the warning! That Bryan guy seems like a real dirtbag. Sells some good products that I haven't found anywhere else though. I'll need to scour the product forum a little more I suppose. How about bicycle-engines.com? I believe that is also a Grubee setup, is it not?

    HoughMade, where did you purchase your kit?


  13. HoughMade

    HoughMade Guest

    Last edited by a moderator: Aug 6, 2008
  14. ocscully

    ocscully Member

    bicycle-engines.com is the retail arm of the US importer of Grubee products BirdDog Industries. BirdDog is the firm that Revolution and other vendors buy from. As to the hub you provided photos of take note that it is a 40 hole tandem hub. You might want to do some searching to see just how readily available 40 hole rims are these days. There are some out there but not very many.

  15. pmarkwell

    pmarkwell Member

    Ok, so I looked at the Gru Bee website (http://www.grubeeinc.com/) and am I right to assume that it comes with a centrifugal clutch in the gearbox?

    I'm guessing that Sick Bike Parts will use the Gru Bee system as well since it's already set up for the GXH50. For the 2 stroke shift kit, why do they run a chain to the downtube, then down to the front sprocket? Is that for stability?

    I've already plunked close to $900 for the GEBE and the GXH50 plus clutch and adaptor so I think I'll just go ahead and use that for the time being once my engine comes in. I'm sure I'm not the only one that's interested to see how it will pan out.

    If I had the know-how and finances, my dream machine would probably be a GP460 2-stroke on a reinforced bike running a chain driven shift kit. Oh yeah, can't forget the CY NOS kit too :shock:. Buy a motorcycle instead, you say. Just dreaming here, folks. I know it wouldn't be safe by any means, but one can dream right?


  16. appye

    appye Guest

    About putting NOS on your bicycle? No, I think even dreaming about it will blow up your engine.:oops: Whaddaya know, I am just about to put together a "GP460 2-stroke on a reinforced bike running a chain driven shift kit" ...
  17. pmarkwell

    pmarkwell Member

    Appye, I've been "stalking" your build since I've been reading the thread on the GEBE/GP460 build. You're going to have a manual shift on a dual rear sprocket, right? I think that's brilliant!

    Do you think that the GXH50 will be too much for the GEBE too? I guess I'll start with what I have, then if it proves that the Honda motor has too much torque or what-not I'll move to a chain drive like you have with you GP460 :smile:.

  18. appye

    appye Guest

    I think it is more of a question of how often and how much riding you will be doing. Like I said, the two main problems with a gebe is belt alignment and ring centering. Don't believe statements about "automatic centering" because of the design. Yes, in a perfect world where spokes don't flex and the ring doesn't slide around (they do and it does) then the thing will stay perfectly centered. The tensioner on a gebe is meant to pivot directly on the surface of a threaded bolt, and does not pivot very well. Using the design from that diagram should ensure (I think, I have not tried it myself) a tensioner design that compensates for out of centered rings pretty well. It also is a good idea to lock the ring down. One user had a pretty good idea for using electrical split bolts to hold the ring in place also. Might want to put a few of those on there. Probably 5-10 ... you don't need to lock every spoke.

    Belt alignment is not a huge issue, so long as you don't let your wheel get too out of round. An off center drive ring will probably contribute to tweaking your wheel out of spec. Just make sure that belt isn't rammed against either side of your drive gear and you will probably be okay.

    Looking back on it, I am almost tempted to give my GEBE another go round with that nicer pivot, but I am pretty much dead set on getting the absolute most sturdy system I can get ahold of because I want to take it to and from work EVERY DAY. I also want to drive up in the mountains a bit too on the weekends and whatnot.

    All this being said, I think that the GEBE belt is plenty strong enough to withstand the stresses put on it by a GP460. Most problems with a GEBE stem from a tweaked or out of round wheel causing uneven stress on the belt. With a chain drive (especially a staton) everything is moved to (and perfectly centered around) the hub, pretty much negating both stress factors.

    What do the rest of you think of my assessment?
  19. BigDaddyT

    BigDaddyT Member

    Nos is pretty innocous. Its the users that get crazy. All nos is 1 part oxygen and 2 parts nitrogen. Air is mostly nitrogen so its a lot like air but air does not have 33% oxygen content whereas nos does. I read somewhere that in a big city air has been tested as low as 8% oxygen content. Where I live I reckon we are 20-24% with good pressure as the vast majority of alaskans live near sea level.
    What nos does is allow you to introduce more fuel into the cylinder because you have higher oxygen content than what is availabe in the air. More oxygen + more fuel equals more power. I dont think the small increase in power will justify the expense of installing a kit.
    I myself wouldnt be against running nos but im not really building for speed. I just need it to be reliable.