Rebuilding Chinese 2-stroke engine - photo tutorial

Discussion in 'General Questions' started by Fabian, Sep 25, 2009.

  1. Fabian

    Fabian Well-Known Member

    G'day all

    Can someone post a photo tutorial with hi-res pics, showing the complete strip down (all the way to rebuilding the crankshaft) and rebuild process of a Chinese 2-stoke motorised bicycle engine.

    Fabian
     

  2. Al.Fisherman

    Al.Fisherman Active Member

    I myself would like to see one also for future reference. Thanks in advance.
     
  3. Porkchop

    Porkchop Member

    Here's 1 phpto

    I don't know if this will help you at all, but it's a photo of my engine I took apart a month or so ago to replace all the hardwear with high strength. Sorry I didn't take more. The engines are pretty simple. Anyone with previous engine experiece should be able to do it with no problem. Not much to them. Dont be afraid to crack them open. Nothng will pop out or fall out of them unexpected. In the photo, you'll see the block halves just as it was when I opened them. Notice the cylinder and clutch plate in the plastic container to the left of the photo. I don't know much more than this. I did not remove the connection rod or anything other than what you see in this photo. If you want/need more info, let me know. I'll try to help.

    ..... PC .....
     

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    Last edited: Sep 25, 2009
  4. Fabian

    Fabian Well-Known Member

    Hi Porkchop

    Great photo, nice hi-res image - exactly how photos should be posted!

    Now can i ask that you do a visual inspection of all the parts, just to make sure everything is bedding in properly; taking lots of hi-res pics of the stripdown, all the way to the crankshaft, to show us where the "D" sized Duracell battery goes and naturally, rebuild process :)

    Cheers Fabian
     
  5. Porkchop

    Porkchop Member

    Fabian, what "D" battery are you talking about? No batteries in my engine. I took only that one photo I posted. I know I said if you have more questions, just ask, but I mmight have spoken before I thought. As I said, I took that engine apart to upgrade all the nuts, bolts, studs or whatever. When I disassembled the engine, the piston rings fell apart into 6 pieces and there was a loose ball bearing inside the case. Good thing I took t apart. Otherwise I would have found out the hard way. This iis a brand new engine at that. It has never had fuel in it nor has ever been started. It's been a while ago since I did this and I don't remember much about it. It was pretty simple and straight forward. And again, like I said, there's nothing in there to pop out or surprise you. I ordered a set of new rings and several gaskets. Reassembled it with new hardwear, used Locktite on everythiing, torqued everything down to 8/ft. pounds as I was instructed here on the forum. If you have specific questions, let me know and I'll try to answer them from memmory. If you have an engine that you want to tear down, just do it. They're about as basic as you can get.
     
    Last edited: Sep 26, 2009
  6. Fabian

    Fabian Well-Known Member

    Hi Porkchop

    My comment about the battery was only to be taken as light humor - check out the upper left hand side of your photo.

    I would still be very happy and grateful if you could make a photo tutorial the next time you rebuild an engine.

    Kind regards

    Fabian
     
  7. Porkchop

    Porkchop Member

    Duh ! I wasn't offended at all. Now I get it. Just a little slow some time. Sorry I didn't take more photos. I took only one to send to a friend. As far as shooting photos of another build, there's probably not going to be any more. The one I have now is my first. I've had to many problems with it and it's never been mounted nor had fuel in it. And I'm not a rookie with stuff either. The bike I have that I was going to put it on is no longer a candidate. It's an old Schwinn that's to nice to modify or destroy. I'm in the market now for another bike to put it on. I've had this engine for aobut 6 months, so another 2 or 3 months is not going to hurt me. I have another friction drive that I ride regularly. It has been no problem at all. I didn't have to re-look at the photo. I know what batterty you're talking about. Anyway, are you fixing to tear down one of these engines ?
     
  8. Foximus

    Foximus Member

    Now this is the first actual picture ive seen of the internals of this motor.


    Im really surprised.... A full circle crank AND twin ring piston. Those look like very thick ring lands. Does anyone know their radial depth?


    Also, do I not see an Iron sleeve in that cylinder?
     
  9. Pablo

    Pablo Motored Bikes Sponsor

    Not super pro but the step by step engine tear downs by Norm are good.
     
  10. Porkchop

    Porkchop Member

    Correct-uh-mundo ! I was under the impression there was a cylinder liner as well, but there isnt. What do you mean by radila depth ? I'm not familiar with that term. I have a set of loose rings though. Explain and I'll measure them and post results. I know the piston mich'ed out at 47mm. That's the largest diameter. Not in the ring grooves.
     
  11. Porkchop

    Porkchop Member

    I am by no means a "PRO" or "EXPERT" on these little engines. Is there a proper procedure to breaking down and putting them back together? I'll do a seaarch and see if can find the post by Norm on this ! They are very simple though from my point of view.
    Thanks !
     
  12. Foximus

    Foximus Member

    Radial depth is the measurement from the top to the bottom of the ring.


    Axial depth is the measurement from the outside to the inside.


    Is the cylinder plated or just a high silica content aluminum alloy? Id be surprised, cause high silica aluminum is relatively expensive to produce.
     
  13. Porkchop

    Porkchop Member

    Sorry !

    I knew as soon as I did not take many photos, that later I'd wish I had. If I have to tear this engine down again, I'll definitly take photos. Since I put it back together I've installed a pull starter and a centrifugal clutch on it as well. I just need to find a bike to put it on and get it running and tweaked.
    Sorry guys. I'll try to do better next time. Also, if someone finds another thread/post about tearing them down and putting them back together, please post. Maybe the one Pablo posted here about Norm might be one. Fabian, you think if we can find a way to utilize that "D" cell that we might be able to gain a little extra power out of these things ?
    Thanks !

    ..... PC .....
     
  14. Porkchop

    Porkchop Member

    I want to make sure I uinderstand correctly. The ring has width and depth or thickness. Is radial the same thing as width. It has nothing to do with diameter, right ? Let me know ASAP. I'm going to the garage right now to get a ring and my michrometer !
     
  15. Porkchop

    Porkchop Member

    Check you PM (Private Message)
     
  16. Porkchop

    Porkchop Member

    Since you're a newbie, do you know how to do Private Messaging. No, I don't think you're dummy. I know I had problems at first and others have too. Heck, I'd been a member for a month or so before I even knew about it !!!
     
  17. Porkchop

    Porkchop Member

    O.K. I see that you do ! Later as I said !
     
  18. Porkchop

    Porkchop Member

    PM me on "forum *****". I don't kniow what that means. Also, let's try to stay on subject here. This thread belongs to someone else. Some don't like it at all when you take over their thread. I respect them. I've had it done to me before. PM anything !
     
  19. Fabian

    Fabian Well-Known Member

    Hi Porkchop

    I am already in the process of design and then construction of a 350 to 500 watt dc generator that doubles as an electric starter motor and auxillary 350 to 500 power assist fed back through the SickBikeParts Jackshaft, shifter (shift) kit to the Chinese motorised bicycle motor.

    My initial goal was to have enough power generation capacity for two 100 watt automotive style driving lights with enough reserve power to run 3 sets of automotive indicator lights and two automotive style brake light sets.

    A side goal was to be able to charge a 12 volt 7 amp hour battery to give short bursts of power to the dc motor/generator, allowing 350 to 500 watts of auxillary power to be fed into the Jackshaft system for emergency overtaking maneuvers of pedal powered cyclists in their expensive lycra bike shorts riding their excessively expensive road racing bicycles, holding up the freight train that is me towing a gross weight of 60 kilos with my trailer and payload combination :)

    Fabian
     
  20. Porkchop

    Porkchop Member

    O.K. Here's what I'm getting 1.97mm for the radial (top to bottom) and 1.87mm for axial (width). I can't tell you anything about the cylinder other than is does not have a liner. I can just say the engine is a Grubee 50cc Starfire Gen. II, manufactured in January 2009. Hope this helps.
     
    Last edited: Sep 27, 2009
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