Simple 4 Stoke Build-Gearing Questions

Discussion in '4-Stroke Engines' started by krealitygroup, Aug 7, 2015.

  1. krealitygroup

    krealitygroup New Member

    11700772_10205754807322497_4484691661155133072_o-2.jpg Hello All,

    I've been on some of the other sites and wanted to join y'all.. I need to build a 4 stoke based on the Honda GHX-50 in a 1990's diamondback outlook 66cm.. I used to have a 2-stroke kit, but it's not reliable enough for the long distance trips I need to take.

    With a 26 inch wheel, what set of sprokets could I get at the engine output and at the rear wheel to get me 25 mph cruising speed with 300# (me and 100# of gear)
    I want to avoid CVT's and jackshafts. simple chain from output to rear wheel and back..

    I appreciate anyone's advice.. Thanks
    K
     

  2. butterbean

    butterbean Well-Known Member

    You may WANT to avoid jackshafts, but they don't make a rear sprocket big enough for you to go direct drive at 25mph, so you're not going to avoid a jackshaft. You will need some other type of gear reduction between the engine and the rear wheel. Check out www.affordablegokarts.com they may have a transmission you can use and it will be reliable and less expensive than others.
     
  3. butterbean

    butterbean Well-Known Member

  4. krealitygroup

    krealitygroup New Member

  5. butterbean

    butterbean Well-Known Member

    Because the two strokes have internal gear reduction. The way the two strokes work is you have a crankshaft, with a magneto on one side and a 20 something tooth gear on the other, then you have a countershaft with an eighty something tooth gear. The crankshaft turns the small gear, which turns the big gear, which turns the counter shaft, which turns the 10t output gear, which drives the bike. No such internal gearing or countershaft on a four stroke.
     
  6. krealitygroup

    krealitygroup New Member

    Ahhhhhh.. I see.. Thanks!
     
  7. LR Jerry

    LR Jerry Well-Known Member

  8. KCvale

    KCvale Motorized Bicycle Vendor

    You won't fit a 49-50cc 4-stroke in that Diamondback frame.
    You pretty much need a beach cruiser S type frame for a 4-stroke.

    I just finished this Pantera yesterday, note that with an S towntube you can get the engine base down to the top of the pedal chain and even then it barley fits, and that is the stock exhaust replaced.

    [​IMG]

    [​IMG]

    The Honda 50cc is a fine engine, the HS 142F-1G 49cc is a nearly part for part knock-off of equal if not better quality for $50 less.
    There is also an HS 144F-1G 53cc 4-stroke.
    Consider it a factory 'bored out' 49cc with a slightly fatter piston for another 100 watts (.13hp).

    As mentioned above you need a transfer case gear reduction on a 4-stroke.

    There are multiple designs for this.
    Skyhawk 4G, a no name 5-G and 7G, a Q-matic and the this AFG one referenced above.

    [​IMG]



    What I have found is all but the 4G rely on your clutch bell and pulley/sprocket to spin on an oillite bushing on the output shaft.
    I feel a bushing has no place in a drive train trying to do the job two bearings should be doing.

    It doesn't take long for that bushing to wear and at idle, start sounding like one of those wind up toy monkey's playing cymbals... on crank, as the bell starts moving and vibrating on the shaft.

    Next is gear reduction and how it is made.
    The old Stage II's used 3 gears.
    Newer stuff uses 1 or 2 chains, or a T-belt.

    I don't like anything chain.
    They are the backup vocals for the spastic monkey.

    I like the HS 142F-1G 49cc and 2015 4G T-belt drive with bearing supported clutch bell and freewheel output shaft with 5:1 gear reduction and nice cover.
    It's quiet, adjustable, and reliable.

    I have a couple dozen 4-stroke builds here for bike idea's if you want.
    http://kcsbikes.com/KCsBuilds.asp?motor=4-stroke&Drive=All
     
  9. butterbean

    butterbean Well-Known Member

    I never had problems with clutch chatter at idle. Taking off is when I would have chatter and slip, but there were a few things I didn't know. You're supposed to oil the bushing every couple of days. I did this, but I used 3in1 oik, and you're really supposed to use motor oil but I never tried that before, what I actually ended up doing was taking it apart every couple weeks and greasing the s.o.b with red and tacky. Not really supposed to do that either, but it worked for me. Now I'm building a new bike with a brand new clutch, and I'm going to use a drop or two of motor oil, I have glass eyedrop bottles so I will be filling that up with oil. Another important thing to realize with the cheap clutches is the gearing, they don't take off as smoothly with higher gearing especially if you are on the heavier side like me. The bike I'm building is geared quite low compared to my last bike, and that will help with takeoff. Also, although the bushings do wear, most one way bearing clutches are needle bearings and I've read that needle bearings don't last as long as bushings. Now if you're talking about a ball bearing clutch, that would be the best way to go.
     
  10. KCvale

    KCvale Motorized Bicycle Vendor

    I agree, that's why I like the 4G's, the clutch bell is isolated from the engine shaft and rides on a pair of sealed ball bearings in the transfer case.
     
  11. butterbean

    butterbean Well-Known Member

    I wish there was a way to turn these cheap maxtorque clutches into ball bearing, they would work a lot better. As it is, you have to rely on tuning, gearing and proper maintenance if you want them to run smooth. Not oiling the bushing makes it wear a lot faster. A properly lubed bushing doesn't wear hardly at all. And I stuck a thick plastic washer under my last one when it got worn really bad, that eliminated a lot of bell noise.
     
  12. KCvale

    KCvale Motorized Bicycle Vendor

    Bearings opposed to a bushing would help but it is still the 'cheap' design.
    Great if it works and lasts, but I don't know of any systems with the engine/transfer engagement system both on the engines constantly turning output shaft.

    The gear reduction system (belt/chain) have their own demands of the clutch bells attached pulley/sprocket to add even more pressure on the bushing.

    Cheap is cheap.
    Best is not.
     
  13. butterbean

    butterbean Well-Known Member

    You have to leave the primary drive chain a little loose for proper engagement. Too tight and it puts sideways pressure on the clutch bell and the clutch overheats and fades. If the chain is loose enough, then when you twist the throttle and the shoes fly out, the weight actually balances the bell on the shaft, if that makes any sense. This puts much less wear and tear on the bushing. Yes, it is still a cheap design but the qmatic which costs twice as much as the agk drive, still uses a maxtorque centrifugal clutch. I know the qmatic is very good and reliable, but other than some issues with the clutch due to lack of knowledge of tuning, gearing and maintenance, I've not had any problems with my agk drive either. It's not always true that the most expensive is the best, and while there may be better options, there are ways to get what you can afford to work for you. You're a professional builder, and the bikes you build are either paid for by customers or with play money you made selling a couple extra bikes. I seriously doubt that you know what it's like to have to build a bike using whatever parts you can afford. The bike I'm working on has already taken me a year, and its got about a grand worth of parts in it. I built my own wheels, and I made modifications to the agk mounting plate to be able to mount my predator engine vertically. I'm using hydraulic motorcycle forks because despite the weight, you can't beat the comfort level and they are tuneable by the amount of oil you add. So I'm not cheaping out, I'm building what I can afford and I'm doing the best job I can. It really gets under my skin when people just assume that if its cheap it sucks. Maybe the clutch ain't that great, but there is a really good clutch called the draggin skin, also made by max torque but of much better quality and more tuneable than the ss clutch, it also costs 150 so if the mods I've made to this clutch don't make it perform how I want, there's also that clutch whenever I can afford it.
     
  14. butterbean

    butterbean Well-Known Member

    Aside from that, I'm running a predator engine and from what I'm told, none of the kit transmissions will work except the qmatic which I'm not spending $300 on.
     
Loading...