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Discussion in 'Motorized Cruiser Bicycles' started by Vfalpha-1, Jun 18, 2010.

  1. Vfalpha-1

    Vfalpha-1 New Member

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    Hi my name is Joseph (16 years old) I'm just jumping into the gas bikes , i have worked with engines before but none with so many "problems" and variables i design aircraft and software so engines come naturally to me , however i have never boost ported an engine I ordered a Grubee skyhawk GT5 66/80 cc slant head. I have read through many many pages on this site to see what needs to be done i have already ordered a tuned pipe, boost tube ( i know some swear by them some at them) hd axel kit i still have the stock carb but have looked at performance mods for it and some other parts for the bike. I ran short on money so i couldnt get the carb i wanted which was a dellorto im still choosing between muniki and dellorto im going to get a sheet of gasket material for re-doing the engine , and i plan to boost port it and work on the intakes , as well as skirt the pistion i have a very steady hand from working with aircraft parts. ANY pics on porting and skirting along with measurements would be greatly appreciated .

    Joseph
     
  2. CoastalCruiser

    CoastalCruiser New Member

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    Run your piston up to TDC with the intake manifold off and then color in what's left showing on the piston with a sharpie pen. Then pull the jug and slug and trim off the marker plus a little bit and smooth it all out. You also might get away with drilling the wrist pin bosses a bit to lighten the piston. You got the GT5 so you already have the hi compression head and domed piston. I wouldn't recommend polishing the dome of the head as that will diminish the turbulence that promotes atomization and good combustion.

    Another thing I've noticed is that the expansion chambers from all but Pypeline are designed for 50cc motors. If I were you, I'd add 2-3 inches of tubing in the center section of the pipe to "tune" it to a length more suitable for a 66cc motor.

    Make sure you have hose clamps on the tubing of the boost bottle and that all connections are sealed. Also a smear of RVT inside the intake before you slide in the carcb will alleviate vacuum leaks in that area.
     
  3. Vfalpha-1

    Vfalpha-1 New Member

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    Thank you so much Coastalcruiser. I have the billet intake from piratecycles but im not sure if that would work with the stock carb, and should i use WD-40 on the grinding wheel to keep it from clogging with aluminum ?
     
  4. CoastalCruiser

    CoastalCruiser New Member

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    Never grind aluminum! Always cut it with a rotary bit or a file. WD-40 is crap (kerosene and water). Use PB Blaster instead. I was referring to a stock carb and intake. If you look inside of the output side of the carb, it has slots to facilitate clamping the carb onto the intake. Those slots are what to fill with the compressible caulking/sealant. On real motorcycles the carb slides INTO a rubber boot. Much better air flow that way, but with these the manifold buts up to a flange inside the carb so there won't be much turbulence there.

    Of course you probably don't have your kit yet so you can't look at that yet.
     
  5. Vfalpha-1

    Vfalpha-1 New Member

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    i dont even know where to get kerosene. is there something that will work just as good ? and do you mean a rotary bit like a dremel cutting bit or the metal one that resembles a milling head ? i dont get the engine until monday . thank you for your patience with a n00b like me i think the intake I ordered takes care of the gap problem i dont have many dremel heads
     
    #5 Vfalpha-1, Jun 19, 2010
    Last edited: Sep 19, 2013
  6. CoastalCruiser

    CoastalCruiser New Member

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    A rotary bit for a die grinder looks like a bunch of blades all welded together- usually drum shaped, oval, or spherical. WD-40 is made of kerosene and water and doesn't keep things from rusting. It only frees up old needle nose pliers and stops squeaks. It has no lubricating action whatsoever.
     
  7. Vfalpha-1

    Vfalpha-1 New Member

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    oh ok i thought you meant to get kerosine what is PB blaster ? and i found what you meant by blades welded together look XD thank you
     
  8. Bikeguy Joe

    Bikeguy Joe Godfather of Motorized Bicycles

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    Just to clarify, one should use K-1 or kerosine as a cutting, or machining lubricant for aluminum, light oil for steel.

    And as stated, never grind aluminum.
     
  9. deacon

    deacon minor bike philosopher

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    I thought wd 40 was made with fish oil...
     
  10. Vfalpha-1

    Vfalpha-1 New Member

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    ok well im headed off to home deopt for the bit and kragens for gasket material i want to replace the head bolts with something a little stronger , so would all thread rods cut to size work ? also since the engine is going to have more power should i worry about using the stock sprocket , wouldnt the rpms be a little on the high side for these engines ?
    and im also going to balance the crank as best I can
     
  11. tim turbo

    tim turbo Member

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    The motors are china made there for they are metric fasteners, if you can find ready rod in metric the right size go for it!
     
  12. Vfalpha-1

    Vfalpha-1 New Member

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    Ok i got High temp gasket material and paint for my bike :) i also got my HD axel kit while i was out. It didn't come with instructions, it shouldnt need them its a simple enough device , if you cant figure it out then maybe you shouldnt be playing with these engines if you can even call them engines XD anyway when my dads new weedwacker broke today he said i can have the other chainsaw , the honda tiller (4 stroke) and the old weedwacker i took the chainsaw apart and got the carb and killswitch the intake on the carb is 18mm and the rear part that goes to the engine is 16 mm there is a dome shape on the inside , like if you where in a building with a dome and its not exactly a smooth transition any way i was wondering if this could be used as a carb for my engine
     
    #12 Vfalpha-1, Jun 20, 2010
    Last edited: Sep 19, 2013
  13. Vfalpha-1

    Vfalpha-1 New Member

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    the little dome i was talking about
     
    #13 Vfalpha-1, Jun 20, 2010
    Last edited: Sep 19, 2013
  14. CoastalCruiser

    CoastalCruiser New Member

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    That is called a "Venturi" and is the most vital part of a carburator. It causes airflow to increase. Don't mess with it.
     
  15. Vfalpha-1

    Vfalpha-1 New Member

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    I still dont even know if i can mount it on the engine , i probably can but im not sure how much better it is than the stock carb thanks CC
     
  16. Vfalpha-1

    Vfalpha-1 New Member

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    well me being a dumbass , not entirely my fault (low blood sugar (Diabetic) i managed to break the crank case , its trashed , so im ordering a new one , the time factor for pending money slows me down other than that the bike is looking good , i used some of the mounting hardware to make a mount for a modifid deurailer. I made the deuraler into a spring loaded tensioner with a lateral adjustment screw. sorry for the typing errors , im tired as **** no sleep yet , working all night . the whole bike was hand painted, tedious work
    stupid crank case :-||
     
    #16 Vfalpha-1, Jun 23, 2010
    Last edited: Sep 19, 2013
  17. freewheeling frank

    freewheeling frank New Member

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    sorry bout the case amigo
     
  18. tim turbo

    tim turbo Member

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    Here,s a little food for thought or tip if you will, try slowing down a tad bit , take your time ,do it right. Start with the basics, get it running, take it for a test run, and then start adding to it,and tweaking the fine tune! I,m an old guy this system has worked quite well for me. Just saying.
     
  19. GearNut

    GearNut Active Member

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    #19 GearNut, Jun 23, 2010
    Last edited: Jun 23, 2010
  20. Vfalpha-1

    Vfalpha-1 New Member

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    yes it tensions the bottom by pushing up and that site doesn't have any in stock :( but i found one that does and im ordering it tomorrow , this week hasnt been my week , engine crank broke laptop fried dad left for a 3 week trip my minivan battery leaked acid all over the engine and on top of that my girlfriend is going on a trip and i cant talk to her for a month
    anyway i balanced my crank in 2 ways laterally and up and down ??? does that count as vertically cause it does rotate, i cant remember the terms , i found an automotive book that helped alot i ported the piston and polished it no sharp edges on it :) she should haul , but i still need to get a smaller sprocket to keep the rpms down when she gets running ill post pics asap

    @ tim turbo, i get where you are coming from , but i've always upgraded things to the fullest , since these engines aren't even made correctly I,m remaking it , in a way as close to properly as i can , i've always done this and it works for my planes and other projects , in my eyes i'm doing it right the first time thank you though , no disrespect intended
     
    #20 Vfalpha-1, Jun 25, 2010
    Last edited: Jun 25, 2010

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