Is there a difference between the skyhawk and the starfire

Discussion in 'Motorized Bicycle General Discussion' started by troyboy, May 5, 2009.

  1. Riding Rich

    Riding Rich New Member

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    Turttle Ted

    I do like the GT-2B it took alot of abuse from me.
    But i'm pretty sure my bottom bearing has about had it.

    Didn't run the PK80-J yet got it taken apart.
    From a Tuners standpoint the PK Looks Good to me.

    Guess i'll have to get a Starfire to take apart and see what it's made of.
     
  2. flybytaco

    flybytaco Metal Molding Madman

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    get a pk the gen 2 a suck compared lol
     
  3. Riding Rich

    Riding Rich New Member

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    Without a doubt i plan on grabbing up a few more of these PK'S.
    It's easy to see the one i got is aswem.

    But i wouldn't mind seeing the insides of all these motors.
    Maybe i'll find a used Starfire that won't run anymore for cheap.

    Fun and allways interesting.
     
  4. adb140275

    adb140275 New Member

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    jet 66 is a nantong jiali... as are the GT4 starfires...



    EDIT: didn't mean to bump an old thread.

    Thanks for biting my head off
     
    #24 adb140275, Oct 29, 2010
    Last edited: Mar 31, 2011
  5. bairdco

    bairdco a guy who makes cool bikes

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    this thread's a year old except for your post, adb140275. but my GT4 starfire runs circles around my GT5 skyhawk.
     
  6. Mind_Reader7

    Mind_Reader7 New Member

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    It never made sense to me when people would bump threads that are this old. Do people do it jsut to annoy me?
     
  7. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

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    why would this annoy you?
    There is some great info in this thread that is still being debated.

    Not too many Starfires left, grab them while you can.
     
  8. muddybike

    muddybike New Member

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    Yeah im sure they had you personally targeted ! J/K
    Tho I would like to say yes sometimes a old thread that is buried has a ton of info that someone getting into the hobby could use ....
    I have to admiot im still not 100% sure what engine i have, maybe someone with some serious time on their hands could build a comprehensive chart with the engine types and changes ....
    Or we could just deal with necro threads!
     
  9. BarelyAWake

    BarelyAWake New Member

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    TBH there's so many "old" threads w/so much good info it seems a shame how rarely they get bumped or even looked for... I can see the problem w/thread necromancy on a purely social forum given that no doubt the OP has moved on - but w/tech, diagnostics & suchlike it's gratifying ta see an older thread continued, saves folks from a lot of repetition & sometimes revives some really well thought out, comprehensive posts ;)
     
  10. bairdco

    bairdco a guy who makes cool bikes

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    this thread's actualy perfect for what i did today...

    the firestone/raffle bike is completely done, and i rode it to the beach today, probably put 20 total miles on it.

    it's got a GT5 skyhawk on it, that i basically blueprinted. match-ported the intake and exhaust, and even matched the transfers. the jug and the case needed a bit of grinding to match up. so, i basically made an awesome motor out of it.

    and the thing's a dog. like, a sleeping dog, that doesn't move when you kick it.

    it has no torque whatsoever, and it takes a while before it gets up to speed.

    it runs really smooth, though, and it'll go fast, it just takes forever to get there. it's actually a pretty well running motor.

    but it ain't no stump-puller.

    on the other hand, all of my GT4 starfires, with the same work done to them, will literally run circles aroung the GT5. even without anything done to them, as in the case of my first motor, will clean the GT5's clock.

    it's seriously such a more powerful motor.

    so, in my experienced opinion, i've built 4 GT4 starfires, and 2 GT5 skyhawks so far. and while they're both good motors, the GT4 pretty much kicks the GT5's a$$.
     
  11. The_Aleman

    The_Aleman New Member

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    I found the opposite true with the GT5. Lots of torque, but down on horsepower. Perhaps that's what ya meant, Baird? Definitely slow to top speed, but they will climb hills real nice at ~4500RPM. Dunno, I have no exp on Starfires, never rode yours. I've had a pair of GT5s and they had plenty of torque. I wish my geared 4-stroke could climb a hill like my 66s did lol
     
  12. bairdco

    bairdco a guy who makes cool bikes

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    nope. i mean, the torque's not bad, but my GT4's will pull off the line in a jiffy, while the GT5's just kinda lumber along, slowly building up speed.

    i have to pedal a lot more to get them rolling along smoothly.

    the firestone bike has a 34t with a MM adapter, as that was the largest sprocket i had, and i figured that would be alright for whoever wins this bike, but i think i'm gonna have to go larger. the GT5 just doesn't want to get the bike going. my GT4's woulda pulled that no prob.

    top speed ain't bad, though. the bike kicks in eventually, about 20-ish, and takes off to about 40 nice and smooth.
     
  13. The_Aleman

    The_Aleman New Member

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    Mine had no trouble on low and midrange, even with a 34T, but they just had nothing for the high end. Took off real nice, strong in the middle. Almost acted like they were running rich, but the plug always read perfect. I ran stock exhaust tho. My GT5 on my Schwinn regularly pushed me to 40 if I wanted it to, but it always fell flat ~7000RPM.

    Edit: oh, and I never ported mine. Bone-stock 24:1 Valvoline and 89, NGK B6 plugs. Never pulled the jugs.
     
    #33 The_Aleman, Apr 28, 2011
    Last edited: Apr 28, 2011
  14. ToxicAz520

    ToxicAz520 New Member

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    Thanks to this old thread geting bumped again I made my choice and ordered a StarFire Gt4 for my next build. I was having a hard time deciding till today.
     
  15. Drewd

    Drewd New Member

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    where did you buy the starfire gt4 engine?
     
  16. ToxicAz520

    ToxicAz520 New Member

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    Pirate Cycles I got the whole kit i could use the extra parts anyway dnt kno where to get this just the motor or i would have done that.
     
  17. flybytaco

    flybytaco Metal Molding Madman

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    the starfire 66 has a diffrent crank, rod, and jug than the gt5. it basically has the same guts as a pk
     
  18. mapbike

    mapbike Active Member

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    I have a BGF slant 66cc on one bike that has a 36T sprocket on it, I just got back from a ride in which I had my GPS on the bike it will hit 39MPH topped out, it's on a Huffy bike that is the same frame as the Cranbrook.

    On my newest build that I just got up and running a couple days ago I have a 66cc engine that has the straight plug head on it, it has the same manic intake, carb jetted the same, and is on a simular cruiser bike that rolls just as easy as the huffy, only difference is the huffy has my home grown exhaust on it and the new build has a SBP expansion chamber on it and I used a good exhaust gasket on it and not that aluminum gasket that just has a little round hole in the middle of it, this new build has a 34T sprocket and all I can get out of it on the GPS wide open is 31MPH, I'm hoping that once I take some material off the head and smoothe up the ports on it like I did the slant head engine it will pull even better and will hit that 39MPH mark as well, if not it will come off and I will be getting another engine for it, I have big plans for this bike and the 31MPH WOT just aint gonna cut it for me, the torque on this engine is great, pulls hills just as good as the slant, but it just goes flat after 31MPH and will not turn a single extra RPM even going down a hill, it just quits right there and maintains that speed for as long as I want but I want a bit more out of it.....

    Ya'll know how it is......we gotta milk it for all it's worth and then just a tad more if possible, thats what makes these little engines so dang much fun.....!

    Peace
     
  19. timboellner

    timboellner Member

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    Taco,
    My jet 66 is an NTJL.
    Whats the difference between the Starfire GT 4 and my jet?

    TiM
     
  20. dmb

    dmb Active Member

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    back in the 70's the biggest atc was the 110 and we would go duneing [glamis] needed more power, honda used small ports to govern motors. we would almost double the intake port size. 24mm carb, cam, stroke to 160cc and much more power. morral of the story is ya gotta make it breathe [porting] to go fast
     

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