Getting all 3 Horse Power out of your GT-5 Sky? (tear down)

Discussion in 'Motorized Bicycle General Discussion' started by recon chris, Jan 19, 2012.

  1. recon chris

    recon chris New Member

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    Are you getting all 3 Horse Power out of your china 2 stroke? I know I’m not. With the untrue rag joint sprocket, the “California Friendly” catalytic converter exhaust, CNS BS carb, unbalanced crank, Chinese bearings, and unmatched porting, I think I would be lucky to get half the rated horse power for the engine on a good day. So I’m changing all of that. Follow along and leave tips. I’ll also be making videos on how easy doing all this really is.
    xct2
     
  2. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Maybe after this tutorial you can show us how to get all 2.5 Horse Power out of the HS 49cc 4-stroke. Just a thought for a future topic.......I've got a few tips for this one.

    dnut
     
  3. recon chris

    recon chris New Member

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    Sorry pics are too big so youll have to click the link.
    This is an engine i have already fully torn down and cleaned. It had about 400 miles on it. Im planing to put 2,100 more on it.

    Crank disasembled and ready for balancing (also cleaned the rust off of them)
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1189crop.jpg


    Crank transfer port before port maching
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1187.jpg

    After
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1188.jpg

    Side by side before and after (not fine sanded yet just did it tonight)
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1183.jpg

    the perfect SKF replacment bearings (sealed for the cluch shaft, Sheilded on one side for crank shaft Ill explain why in the video i post)
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1195.jpg
     
  4. Rocky_Motor

    Rocky_Motor New Member

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    A video on a happytime rebuild? Im excited, I'd love to see how to do every part of it! Ive been wanting to do this even just for fun and have it ready for a future build
     
  5. recon chris

    recon chris New Member

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    These are the difference between the two bearings I’m using in the engine. One has a metal shield that doesn’t touch the inner raceway and the other has a plastic seal that presses against the outer and inner raceway keeping all dirt out.

    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1190.jpg

    side by side
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1191.jpg
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1192.jpg

    Somthing you should read before you tear down your engine
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1194.jpg
     
    #5 recon chris, Jan 19, 2012
    Last edited: Jan 19, 2012
  6. recon chris

    recon chris New Member

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    Im going to stick to 2 strokes for this thread Scotto- but someone should post a thread for 4 stroke performance that is my next build :)
     

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    #6 recon chris, Jan 19, 2012
    Last edited: Jan 19, 2012
  7. scotto-

    scotto- Custom 4-Stroke Bike Builder

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    Here are a few pics of 4-stroke performance......


    URL=http://imageshack.us/photo/my-images/827/img0994a.jpg/][​IMG][/URL]

    URL=http://imageshack.us/photo/my-images/535/img0978r.jpg/][​IMG][/URL]

    URL=http://imageshack.us/photo/my-images/213/img0754vy.jpg/][​IMG][/URL]
     
  8. dmb

    dmb Active Member

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    lotsa room for big valves in their scotto, but too big will ruin botton end just like too big of two stroke ports can do the same thing. a happy medium is best for single speed motors. recon chris im looking to see how you unshroud the transfers, maybe relieving the piston crown?
     
  9. recon chris

    recon chris New Member

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    How the work bench looks so far. Look at all those clean parts. Hard to believe that i have been riding it for 8 months :)
     

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  10. recon chris

    recon chris New Member

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    Some things I did today:

    Polished the head (I had already tried it about 200 miles ago, so that is why the before shot doesn’t look so bad.)
    Before
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1236.jpg

    After
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1240.jpg

    Opened up the transfer ports about 100%

    Before sanding with material already removed
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1213.jpg
    After light sanding
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1214.jpg

    Corrected an odd casting defect that was left over from the factory. Im guessing every grumbie has this. It has to hamper performance by a good percentage if left uncorrected. I had to pull a Houdini to get a dermal bit in there without scratch the walls of the jug.

    Before
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1213.jpg
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1219.jpg
    After
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1221.jpg
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1218.jpg

    Cleaned the carb up. Left the air filter off because I will be upgrading to a SBP low profile air filter (a million times cleaner and more efficient than stock sponge)

    Before
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1226.jpg
    After
    http://i1072.photobucket.com/albums/w364/reconchris/CIMG1249.jpg

    And got a new Piston today (old one had one of its position pins vibrate loose, I stoped it before it killed the jug)
     

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    #10 recon chris, Jan 19, 2012
    Last edited: Jan 20, 2012
  11. recon chris

    recon chris New Member

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  12. recon chris

    recon chris New Member

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    DMB what do you want to see I dont undersand. I have it all apart so i can show you whatever you want.
     
  13. recon chris

    recon chris New Member

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    I have a question for you guys. How hot does the head on this engine get. Would it be ok to paint it with 500 degree engine paint or will it not be enough. I was searching on line and aparently there is such thing as 1200 degree engine paint. But i dont know were to get that stuf.
     
  14. azbill

    azbill Active Member

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    I have had good luck with Duplicolor engine enamel with ceramic (500 degree)
    (I get mine at the local O'Reilly's ;))
     
  15. recon chris

    recon chris New Member

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    Do you have to bake it on and what is ceramic about the paint? And does it dry Glossy and stay glossy after the engine has been run? I hate engines that have matt finishes.
     
    #15 recon chris, Jan 20, 2012
    Last edited: Jan 20, 2012
  16. dmb

    dmb Active Member

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    hey recon chris first thank you for serving. what i was talking about is that the piston at BDC blocks the transfer ports exposing only part of the port sorta like a restrictor port. my worry is with a cut intake skirt and blocked transfers could put to much pressure in the botton end blowing the seals. maybe raising the port would work and the blocked lower part of the port would help cool the piston a little. by no means am i a two stroke engineer heck most of my spelling is wrong. please dont take my questions wrong im just a interested by stander. as far as paint cast iron stove paints work good on motors and exhaust pipes good luck dennis
     
  17. jimmeyphat0314

    jimmeyphat0314 New Member

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    lovin this thread!!! thanks. been a little scared of trying a tear down, but all the pics so far have given me some hope.
     
  18. recon chris

    recon chris New Member

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    Well I'll look at the piston at BDC and if it needs the intake skirt mod im going to do it. Im not woried about the seals blowing out because of two reason.

    1.The intake mod will not increas the pressure in the case by an extreem amount (maybe a few psi if im lucky)

    2. Im replacing the seals with slightly thicker double liped oil seals from Motion Industries. (the originals are made from china and only have one lip ((even on the thick drive pinion gear side)))

    When i set it up ill show you pictures

    However were do you ge the cast iron paint and does it come in spray can form?
     
  19. recon chris

    recon chris New Member

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    Jimmy the one thing I have learned so far is to not baby this engine. And by all means dont be scared of it (coming from a guy who was scared to take it apart myself). Just tear it apart and replace the things that matter and make the mods that make sense to you.

    The bigest benifit I think I will gain from all of this is knowing that ill have a bullet proof two stroke that wont break down, and if it does ill know exactly what might be wrong with it.
     
  20. dmb

    dmb Active Member

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    i think any home improvement store will have the paint. the piston mod is at TDC but BDC will show the blocked transfers. im surprised no one has welded a reed block to the bottom of these motors and blocked the intake port. reeds work very well on two strokers and you can use the complete up stroke for the air fuel charge. all your work looks very good to me and i'm sure your going to get the HP your looking for. dennis
     

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