Centrifugal vs. Clutch Engines

Discussion in 'Motorized Bicycle General Discussion' started by Wood.Neely, Feb 12, 2011.

  1. Bob Mac 18704

    Bob Mac 18704 New Member

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    Is your motor a ggg motor that came from the factory with pull start and cent. clutch installed. If so that may be the case. I'm not too familiar with the ggg motor. I bought a cent. clutch and installed it on a reg. skyhawk 66 cc motor. I have no pull start on my bike I bump start it all the time because i have no other way.
     
  2. professor

    professor New Member

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    Adam- what engine did you get the recoil off of?
     
  3. joabthebugman

    joabthebugman New Member

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    Why can't these thing be simple???
    I was looking into a cent clutch also but didn't want the pull start

    So lets see if I am correct here

    If you buy an engine with a factory cent clutch you have to pull start but if you install an after market cent clutch you can bump start??

    here's another question
    Does the cent clutch rob the engine of any power
     
  4. kerf

    kerf New Member

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    I'm not running a Chinese frame mount but I am running a centrifugal clutch. The centrifugal clutch won't cost any power, it should lock up just like the manual clutch but smother. You only need to control the throttle to feather the clutch.
     
  5. Bob Mac 18704

    Bob Mac 18704 New Member

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    The reason I say that about the ggg motor is because I don't have one to try it. I honestly don't see why that motor would be any different than mine.From what I read the only thing different is the end of the crankshaft on the ggg. The original clutch is still in there and it still operates if you hook up the cable. The cent. clutch is installed off the small gear, which would be the output gear. Once the chain is put on you can't roll the bike without the engine turning over. If you pull in the manual clutch the bike will roll freely. The one way bearing on the front of the cent. clutch is a touchy thing when you are installing the clutch. If you push the clutch on the shaft and the bearing pushes out the front the barrel shaped bearings will fall out and it's frustrating to get these lined up right. Once the clutch is seated right you will notice that the clutch only turns one way. If that bearing is not in their for whatever reason the bike will run by pull starting only.I cannot see that bearing not being in there because the bushing is part of the bearing. Now if it was installed without one of the barrel shaped bearrings (fell into the giant big hole into oblivian) the bearing won't work and you won't be able to bump start it. This is my experience only but I think I have a handle on how the cent. clutch works. Others mileage may very. I'm done with this subject
     
  6. madwheels37

    madwheels37 New Member

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    what's a ggg motor? and what does HT mean?
     
  7. madwheels37

    madwheels37 New Member

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    how does it work with bump starting? That's the only part I'm really confused with then, because it's automatically neutral right? Do you have to just pedal real fast or what?
     
  8. kerf

    kerf New Member

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    Yeah, I'm not real clear with some things being said here. If someone were to post pictures, we could have a real learning moment.
     
  9. Scotchmo

    Scotchmo New Member

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    If you are talking about the HT engines, that is not always true. The GGG-1 cannot be bump started. It does not come with a hand clutch. I have never seen one in the USA. All of the dual start GGG-2 engines with centrifugal clutches, pull starts and hand clutches can be bump started or pull started. Most of the retrofit centrifugal clutches for the HT engine have the one way bearing that allows it to be bump started.
     
  10. Drewd

    Drewd New Member

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    HT centrifugal clutch engines are pedal started (not bump started). Both of my bikes have centrifugal clutches and both are pedal started though one has pull start that works for 3 pulls before it breaks. If you pedal start and have a slant head, make sure to get the upgraded freewheel assembly if you decide on using a shift kit from SBP.
     
  11. LS614

    LS614 New Member

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    You do realize that pedal start and bump start mean the same thing right? :)
     
  12. adam valentine

    adam valentine New Member

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    gas/kings bike is where I bought mine, I did have to do a lot of work to make it run right. I do have a clutch handle, although to make the cc work right I did have to remove the bearing y'all are talking about, because I believe it was installed backwards. When I first installed it, it was like the cheap motor and I had to pop start it. The cent clutch did not work after removing the bearing it did work, but I now have to pull start it only.... I did loose low end starting off power over the clutch, and it added slow speed vibration but normal running speed is awesome, in fact it runs better than ever at high speed, but that could be due to break in.... I did have a little rubbing on the cc shell but it rubbed its way free and im very happy now.... I do have an un adjustable carb and at idle I have to give it gas and hold bike back but going on flat and wot its faster than I want to go on a bike. Pull start did break without me ever pull starting it ever but I replaced steel cable with lawnmower rope start and it works great now. I can start it and burn out with cc without me on the bike, I weigh 250 hills do make it slip worse but I can now give it gas from a stand still now....and take off although it vibrates bad on low speed, I am very happy with it once I get my bike running right it will be awesome. Go for it you'll be happy I,m looking for a full face helmet today!!!! I sealed the big carb last night, I cant wait to ride again today or tomorrow!!!! And I do have a car and a truck, I just love my mb the engine is a grubee sky hawk cns carb with choke on handlebars, 2010 no slant head, black motor epa exhaust cc pull start just like the web sight offers for 200 bucks and its mounted on a Schwinn beach cruiser. I get a lot of compliments and stares and would love for anyone, once I get all the bugs worked out to have this combination..... Its simple to use, yet does beyond the call of duty !!!! Two thumbs up here!!!! cvlt1cvlt1
     
  13. flybytaco

    flybytaco Metal Molding Madman

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    your absolutely wrong. and yes there is a 1 way bearing or a sprag bearing and would you like to see a vid of me bump starting my centi clutch motor? one problem that will probably occur is your wider clutch cover and pull starer willhit the pedals
     
    #33 flybytaco, Feb 16, 2011
    Last edited: Feb 16, 2011
  14. adam valentine

    adam valentine New Member

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    yea i did have to install the wider crank but I also know i can not bump start mine in fact i never pull my clutch in anymore it always stays engaged and heck yea all of us gear heads love to watch videos soo yea post it
     
  15. Creative Engineering

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    I've never had one of these...but it makes sense that a sprag is used.

    For those who don't know what a sprag is: It's a one-way bearing...the same concept as the freewheel sprocket. It spins freely one-way, and locks when rotated in the opposite direction.

    I assume that the sprag/bearing is between the clutch bell and the crankshaft. The mounting hub for the shoes would be directly connected to the crankshaft.

    When bump starting, the clutch bell locks with the crank to turn the engine over. Once the engine is started the crank spins freely inside the bell, until the shoes expand and drive the bell.

    What I don't understand is:

    How you could simply remove the sprag/bearing without replacing it with something? Standard bearing, bronze bushing, something.

    Is the bell supported by 2 bearings?

    I would like to see pic of this.

    Jim
     
    #35 Creative Engineering, Feb 16, 2011
    Last edited: Feb 16, 2011
  16. Venice Motor Bikes

    Venice Motor Bikes Custom Builder / Dealer/Los Angeles

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    The pull starts I've seen didn't have those.... I learn something new every day! :)
     
  17. Drewd

    Drewd New Member

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    No, I took bump start meaning the bike is pedaled and the clutch is released causing engine to turn over and start. Pedal starting is a little harder because it requires lots of weight on the pedal to overcome inertia and pedal thru engine compression to start engine.

    Regardless, I haven't met a centrifigual engine that can't be started without a pull start.
     
  18. LS614

    LS614 New Member

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    Ok, lol, on my own bike my tire just will not move if i try to start it from a dead stop which I think is what you mean. I can ONLY start my engine by pedaling up to speed and letting go of the clutch. I was the confused one here I think, sorry :D
     
  19. bigbutterbean

    bigbutterbean New Member

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    this guy at venice bikes sure doesnt want you to buy one of those engines. Here is what I did. I bought parts from gasbike to build the engine myself. I bought a 48cc pull start crankcase and a 48cc tope end. the pull start that came on the engine was cheap. Plastic pawls and a cheap nylon rope that broke after about 15 or 20 pulls. But also in the box was a heavy duty pull start, all metal with a steel cable for a pull rope. I am ssuming that it was included with the crankcase. Now the new Grubee pull start engines are claiming to be pull start or pedal start. I wouldn't know for sure, since I have not taken mine on the road yet. I am having issues with gasbike over other parts that I ordered, and therefore can not take my bike on the road at this time.
     
  20. madwheels37

    madwheels37 New Member

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    Yeah from what I hear you can do everything that venice says you can't do. No offense man I'm sure you probably have lots more experience than I, but it's the popular concensus...? And I also hear the same thing about gasbikes and king's, (same company?) Anyway I feel like I might just try it and sorry to hear bout your probs, never a good time with that nonsense.
     

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