Huaseng/grubee Transmission failure

Discussion in 'Frame Mounted Engines' started by IASheer, Jul 9, 2011.

  1. IASheer

    IASheer New Member

    I've got one of the 4g engine kits from Spooky Tooth Cycles (Got it last september, I think). It took me a couple months before I had the time to put the bike together but once I did, oh, it was wonderful!

    Until a short while back when I was riding. I went to apply gas, and the engine revved... and there was a loud, metal 'CLICK!' sound from somewhere in the transmission. Then the motor kept revving, I didn't accelerate. At first I thought the belt had slipped off or something, but the belt's fine. After checking the transmission over, it seemed there's something wrong in the bits attached to the chain sprocket and the big belt wheel. The axle for the chain sprocket can turn independently of the large belt wheel, in both directions.

    So, my question is this: I have no idea if this is fixable, or if I have to buy a whole new transmission. What do I need to fix this, where do I get it, and how much will it likely run me?

    Attached is a picture (sorry for blurry, it's done with my craptastic cell phone camera) of the transmission in question.

    Attached Files:

  2. maltese guy

    maltese guy New Member

    It sounds like the freewheel sprocket that connects the chain to the rear wheel is broken,or maybe the key that holds the sprocket from turning on the shaft coming out of gearbox is broken.check these 2 things first.hope thais helps you resolve your problem.
  3. ocscully

    ocscully Member

    One-Way Bearing Failure

    The kit you bought was one of the early Grubee 4G Drives That use a one-way bearing ( the bearing underneath the cir-clip in your photo) in the 80t driven pulley of the drive rather than a freewheel on the output shaft of the reduction drive. These bearings were the subject of a recall of sorts. But at this late date I think you are going to have trouble getting the bearing replaced as SpookeyTooth is no longer in business. You could try contacting the folks at as they purchased the business and all of the inventory, maybe they have some of the replacement bearings available? Some members have welded up the damaged bearing with some success? Or you could replace the 80t pulley with one of the older 100t pulleys from Both of these options are going to leave you with a drive that no longer freewheels. This isn't really a problem as you still have the clutch that disengages when you let off the gas. If you go with the larger pulley you will also have to get a longer belt 570mm to fit properly. The other fly in the ointment right now is there seems to be no stock of grubee 4G drives or parts at any of the vendors in the US. bicycle-engines does a a few leftover parts from their previous order (they currently have the larger pulley) but do not have the belts available. Another option would be to try and find a replacement bearing from a local bearing supply house.

    Last edited: Jul 10, 2011
  4. IASheer

    IASheer New Member

    OCScully: Thanks for the help, but some of what you're saying is going right over my head. I think I know what different parts are, but not what they're called. cir-clip, for example. ^^;;

    It' looks like has the transmission I need, but only one of them (the more expensive one, of course) has the bell housing visible- it's the 'Honda' one. I realize that it's out of stock, but if that's the one I need, I can find out if they'll get it back in soon.

    How would I go about talking to BikeBerry about this? I don't know if I have any of the order information for my kit any more, and I don't know if I even had a warranty on the kit, the parts, or what-have-you.

    Taking this thing apart to get at the bearings? Guh. Don't know how to take it apart, and I'm worried if I take it apart, I'll never get it back together. I don't know if I have the tools for it, either. Short version- if I have to, I'll try, but it scares the **** out of me.

    Lastly, when the transmission died, I went looking for a replacement online, and found one at King's Motor bikes. ( It looked right, and there wasn't much to go on (Spooky Tooth was dead, and this was the only thing that seemed to fit the bill) and so I bought it. Hey, it... sorta... fits. >.<

    The screws line up and the whole thing fits in place with a little finagling. But the teeth on the sprocket are a little too wide. Would filing them down work, or did I spend $100 on a transmission I can't use?

  5. occchopperfl

    occchopperfl Member

  6. ocscully

    ocscully Member


    Here is a link to BikeBerry Call them and see what they have to say. The worst they can do is say No.

    This second link is to Grubee info pages
    click to continue, total products, 4 cycle engine kits, 4G service parts and instructions. Frame Mount #1 HuaSeng Centrifugal Clutch

    The Grubee pages are just for information and you can not order parts from them.

    The Drive you have is the 2010 version of the 4G for the HuaSeng 142F/CC motor. This motor comes with the clutch shoe pack mounted to a very short tapered output shaft/crankshaft on the motor. The other unique thing about this drive is that it uses a one-way bearing pressed into the center of the 80t driven pulley to achieve a freewheel action on the output shaft of the drive. This bearing is what has failed in your drive. If you can get a replacement bearing, you simply remove the old bearing and press in a new one. Very early on Grubee became aware that the bearing was not up to the task and sourced a different one, sent out a notice that there was a problem and said you could get replacements from your original supplier? in Montana is supposed to be the US Importer of these kits and to the best of my knowledge they have never offered the particular 4G Drive you have, with any of their kits or as a separate item. SpookeyTooth is one of only two vendors I know about that has sold the particular 4G Drive you have. The other is EZ Motorbikes in Dana Point CA.

    As for when replacement parts will be available, by all means call the folks at and see if you can get a firm answer. Be aware that bicycle-engines does not respond to e-mail and you will need to give them a call to get an answer. Also be aware that they have published and missed several deadlines this spring and summer and have changed their notice on their site that items are out of stock with no product due dates listed.

    The fastest way to get yourself back on the road would be to take the 80t pulley off your drive unit and have the bearing in the center of it spotwelded in a couple of locations around the inner race to make it fixed. You are turning the bearing into a fixed hub, remount it and your back on the road. If you feel that this type of repair is beyond your skills or ability to find someone to do the welding for you,and just want to replace the drive unit then the unit from BoyGoFast will fit your motor, but I question the overall quality of the drive, and this drive is only approx. 3:1 reduction where your 4G unit is 4:1, You will probably need to get a larger rear sprocket to make up the difference.

    A Cir-Clip is a retaining device that is used in this case to keep the one-way bearing mounted/pressed into the center of your 80t pulley. Its made of spring steel and fit into a groove that is machined into the bore of the pulley and keeps the bearing in place. Its the black C shaped ring in the original photo and has a small hole at each end to allow a pair of cir-clip pliers to grab it and compress it so it can be removed or installed.

    The drive you bought from Kings Motors is pretty much the same drive that BoyGoFast is offering. The fact that the chain does not fit seems odd. I don't use the larger type chain on my bike so I not real sure just what chain to recommend but I think its #415 that is the widest?

    Last edited: Jul 11, 2011
  7. IASheer

    IASheer New Member

    I'm honestly not sure which chain I have; it's the original chain which came with the kit I got from Spooky Tooth Cycles' 4g engine kit.

    I'd really rather not spend more money than I have to (and I regret buying the KMB/BGF transmission), and am I stuck with the transmission model that came with the kit? I think you mentioned that this was a 1st generation transmission; would a newer version still work?

    I'm assuming I'll need a set of Cir-clip pliers to fuss with the cir-clips; can they be found at a hardware store, or do I need to look somewhere for them in particular, and what's a good price for them?

    Also as for chain width, are you referring to the space between the round bits with the pins in them that hold the links together, or the flat plates that form the sides of the links?

    Plus, the chain I have fits my rear sprocket fine; if I replace it with one to fit the sprocket on the BGF transmission, won't I have to replace the rear sprocket as well?

    Lastly, where do I find out what kind of bearing to ask for when talking to BikeBerry or

    And thank you so much for the patience and help, OCScully.
  8. ocscully

    ocscully Member

    If it were me I'd put all of my time and effort into making the 4G Unit functional again. I just don't believe you will ever be happy with the newer drive unit from Kings. Cir-clip/snap ring pliers can be found at Hardware stores or Sears Harbor Freight, has a set of 4 pliers currently for $5.50 for the set. (see photo below)

    The second photo is the bearing that you currently have that is broken, and the third photo is of the so called newer improved bearing. If you were to remove the 80t pulley from your drive unit (remove the bolt that threads into the center of the shaft, you should be able to gently wiggle the pulley to get it off the shaft?) Then use an exacto knife or small screw driver to remove the bearing seal. Where this seal is located is where you want to have the bearing spot welded. If you don't know anyone with a welder look up welding schools in your area and phone them to see if they have any students that could do the job for a small fee. Its the kind of job that should only take a few minutes to accomplish. Once the bearing is welded you just reinstall the pulley and you should be good to go. Here in Costa Mesa, CA I could probably get the welding done for $20.00 or less.

    As for finding a new bearing as I said the first place I'd try is BikeBerry, Phone them and ask to talk with one of their tech. people about the 4-stroke 4G kits they had for sale, and ask if they have any of the Newer Improved One-Way Bearings for the 4G drive Unit. Be honest with them and let them know that you bought your kit from SpookyTooth before they went out of business, and you haven't been riding your bike much and that it has recently failed. Maybe they will have one and they will be able to sell you one, maybe not? If they don't have any and you want to spend some time looking for one from a Bearing Supply source here in the US, you need to search for a 44mm OD X 15mm ID One-Way Bearing.

    Getting your current 4G unit to work means the problems that have come up with the chain will go away as well.


    Attached Files:

  9. IASheer

    IASheer New Member

    Thanks for the advice, OCScully. I'll give BikeBerry a call today (Since it;'s my first day off and my first chance to do so) and see what happens.
  10. IASheer

    IASheer New Member


    Just got off the phone with; they're shipping me a replacement bearing. Not expensive at all, and very helpful as well. Fingers crossed, and here's hoping!
  11. IASheer

    IASheer New Member

    Update #2!

    So the bearing arrived in the mail about five days ago. I finally got the chance to replace the bearing in the transmission, and now... dun dun dunnn! The bike works!
    OCScully, thank you so much, you were a huge help. The same goes to the guys at, you guys rock! I'm up and running. And tomorrow... PICTURES.
  12. IASheer

    IASheer New Member

    Update #3. August 7th. 13 days after I install the new bearing... it breaks. ;_; Gonna call BikeBerry tomorrow morning.