Splitting the crankcase

Discussion in 'Motorized Bicycle General Discussion' started by Blm25super, Jul 19, 2014.

  1. crassius

    crassius Well-Known Member

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    I grab those woodruff keys with a pair of dikes and then just raise the handle of the dikes to pop them right out
     
  2. Blm25super

    Blm25super New Member

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    yep it were the woodruff key. got the crank out finaly. Imgonna order another crank and possible another bottom end. But they have to be a gt-5 model so they will work with my fred head engine kit. Anyone know where I can order that from ? I dont wanna order one and find out it is a pk-80 pr gt-5a. . . . . Then once I do that I want to have both cranks balanced whatever works the best. If anyone knows anyone that can do this please message me the info so I can get this show on the road.
    Im wantin someone to do what ole fred is doin here. Im tryin to get him to do a couple cranks for me but i think he is kinda busy.....

    https://www.youtube.com/watch?v=h0mVFMgFqqE&list=UUpQonqnDnUV-PX6aASOTf7g
     
    #22 Blm25super, Jul 24, 2014
    Last edited: Jul 24, 2014
  3. Davezilla

    Davezilla New Member

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    The GT-5 engines are a little harder to find if just looking for a new bottom end but you could try gasbike.net or send Roger a Pm and ask where he buys most his parts from. Roger knows his stuff quite well and he prefers the GT-5 engines over the PK-80 type so he may know a few sources that most of us don't know about.
     
  4. Blm25super

    Blm25super New Member

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    Thx dave i just emailed him
     
  5. rogergendron1

    rogergendron1 New Member

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    didnt get your e mail... just pm me and i will list my parts source.....

    http://custommotoredbicycles.com/ga..._piston_kit_49cc_parts_for_motorized_bicycles
    well most of the single pieces are ordered from

    aas you can see you can seperatly order a 38mm or 40mm full circle crank with ether a long or a short rod, and you can order the rods seperatly ... this allowes you to build what you want in whatever case ... this site has a lot of good parts and a great variety of them too including 40mm spaced intake jugs !

    other than that if i want to order a full all together GT5 its through gasbike or whereever i can find one LOL

    but if you know how to punch out the bottom end bearing on the crank and remove the con rod or your dareing enough to DIY then you can convert a GT5 crank to use a standard PK80 pisston and jug by swapping con rods and pistons thus making the future procurment of parts mutch easyer.

    if its a new crank and con rod your after then they have it it will be a...
    38mm sroke full circle crank, with the long 115mm rod, and you will need a high wrist pin piston, and i sugest you run a better needle bearing since you mentioned your gonna run a fred top end !!!!!!

    you can get the needle bearing through treatland its a puch moped bearing i forget what number though .... a quick search should bring that right up.

    just do not buy a grubee unless it comes with the CNS V3 carb !!!! this is not me saying it, to get you to use that carb its actually because those that came with that carb are the better quality ones, beter bottom ends !!!and large bore long Z intakes!!! and if you can get through the cns v3 tunning you will get more responce from it than an NT and more top end also in my opinion.
     
    #25 rogergendron1, Jul 28, 2014
    Last edited: Jul 28, 2014
  6. Blm25super

    Blm25super New Member

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    The difference between the engines then is the connecting rod only?
     
  7. Davezilla

    Davezilla New Member

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    Mainly the rod and piston, but there are a few subtle differences in the cylinder as well... Gotta go GT-5 all the way or PK80 all the way for the rotating assembly and top end.
     
  8. rogergendron1

    rogergendron1 New Member

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    there is also a differance in stroke !!!

    the dax f80 has a crank thats ground for 40mm stroke and all others are 38mm

    so if the biggest motor is what your after then make it a dax kit

    but you can get the other 66cc motors anywhere

    if you want ease of parts availability then get a dax or pk 80 you will have a true 70cc motor that has standard parts

    i like the grube gt5 personaly though to build apon i just seem to be able to extract more power from the stock factory port map than any other motor even though its only 66cc vs 70cc. the gt5 has differant and parts are hard to come by so be warned
    IE: the jug has differant porting and the rod is longer and the piston has a differant wrist pin location
     
  9. maniac57

    maniac57 Old, Fat, and still faster than you

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    MotorBicycleRacing also sells the 40mm stroke engine and parts. His "GenV" is every bit as good or better than Dax's best. PM him for availability and prices
     
  10. Davezilla

    Davezilla New Member

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    Very True... Dax or MotorBicycleRacing are the only places I'll buy a complete engine from... very noticeable difference in smoothness and quality. Not sure which one is best, or if they're both the same in quality, but you can't go wrong with either engine.
     
  11. Blm25super

    Blm25super New Member

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    okay i am a bit confused. I talked with thatsdaxon the phone and was told that some of the gt-5 have 40mm cranks and some have 38mm. And what exactly is that measurment from anyways?
     
  12. Greg58

    Greg58 Well-Known Member

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    That measurement is the distance from top dead center to bottom dead center, or the distance the piston travels in the cylinder. I measure it with a pocket ruler, its easy with the head removed.
     
  13. Blm25super

    Blm25super New Member

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    thx now if i can just get a gt-5 bottom end. ... for my gt-5 fred engine kit.
     
    #33 Blm25super, Aug 9, 2014
    Last edited: Aug 9, 2014

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