My review of the GT5_A Superhawk

Discussion in 'Motorized Bicycle General Discussion' started by richirich, Sep 5, 2011.

  1. richirich

    richirich New Member

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    Let me start by saying that i was repacing my 58cc phantom edition motor with the GT5_A, not that there was anything wrong with it. I just wanted to have a broke in back-up motor. As far as hte GT5-A is concerned is to know it is set up for a small down tube frame the other motor was for large frames.So i had to order the large frame adapter from SBP. ordered it on thursday night, had it on saturday)"SBP is great". In the meantime i replaced all the hardware from the screws to allen socket head cap bolts. I replaced the studs with 5.5 grade. Sunday morning i was ready for the test fire up. filled the tank with priemium fuel and 20:1 Castor927 pro series oil. I went alittle up my alley and got rolling then poped the clutch and wham it fired right up.i went around the block and it feels very powerful, unfortunatly i heard the exhaust leaking. i had a custom exhaust already that was set up for the other motor. the angle on the head was a little different but nothing the dremel on the pipe couldnt handle. i checked the torque on everything and it seemed fine. went for another ride all was going well untill i started to go up an incline then heard the "wap wap" of a leaking head gasket. I had replaced the head studs with 5.5 gade studes and had checked the head on fine sandpaper so i know that was ok. i started with 10ft # so i upped it to 12FT # took it out fror another ride. same thing when i would go up a slight incline and the compression would have to work (wap wap ) leak. so i tried to go to 14 FT# on the torque and the studs stripped . i guess 5.5 is only good for 12# So i would have to assume with the high compression of this motor that a realitivly high torque is needed. so now i have to wait a coulple of days for new head bolts from SBP. on my other motor i serously milled the head for high compression and replaced the studs with high grade SBP ones and had to torque to 17FT# on 6mm bolts with no leaks no problems.
    But overall everythging else has been just fine. i am higly impressed with the power of this motor. even at quarter throttle and a leaking head gasket it pulled me up a hill with ease.
    Another good thing about this motor is the large intake and exhaust ports. There hugh compared to normal motors. It comes with a matched intake but the exhaust is big, be prepared to break out the dremel and do some major grinding if you want your pipe to match.
    Overall i like it, ill post the results of the head stud change in a few days. I hate waiting for parts. Sometimes it feels like your waiting for parts more than you get to ride...
     
  2. bairdco

    bairdco a guy who makes cool bikes

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    i've got one, also, and the exhaust port on the engine is the same size as all my other motors, it's the intake that's bigger.

    i built the bike for a friend, and it's blown 2 headgaskets so far, both times warping the head, which required sanding on glass, which also means increasing the compression.

    if it blows again i'll probably swap it for a straight plug head from an older engine.
     
  3. richirich

    richirich New Member

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    i guess i was comparing the exhaust port to my 58cc motor. it has a large round port. So trying to gind out the header to the rectangle was a chore. Not wanting to be grounded for a few days waiting for the new head bolts i put the stock ones back in and torqued them to 12FT#. it seems to be holding but i have just been taking short trips around the block with a little less than half throttle.

    How much torque were you putting on the head bolts?
     
  4. Tohri

    Tohri New Member

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    where did you guys pick up these motors? ebay? I might want one to, er, play around with.
     
  5. richirich

    richirich New Member

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    I got mine from Piston Bikes. The web site does not show that they sell the motor only, if thats all you want you have to call them , but they will sell the motor only.
     
  6. bairdco

    bairdco a guy who makes cool bikes

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    i got mine from Piston bikes, also.

    as far as head torque, i tighten it with a small socket wrench till it feels like if i go anymore they'll strip. i don't own a torque wrench. i've got a good "feel" for it.

    i'm trying to find some time to work on a motor for my bike, and detail it as i go, but work keeps getting in the way.
     
  7. mapbike

    mapbike Active Member

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    I do the same thing Baird,

    My Granddad had a small engine repair shop at his home for about 50 years, he worked on everything you can imagine, restored old tractors,automotive engines, rebuilt large water pumps, ect.... the man never owned a torque wrench in his life and never needed one either.
    I know there are acceptions to this on some of the high tech modern Aluminium stuff but for those of us that have been tinkering with and building small engines like these china girls and the such for a long time, we dont need a torque wrench, it's all in knowing how it feels and tightening bolts & studs in the right sequence, it's all feel and technique for me as well and I've yet to strip anything on one of my engines or have any blown or leaking gasket issues.

    Hope you get the time to get to the engine asap..... I know what you mean about the working........been work work work....for me lately also, a lot of stuff going on.

    Peace, map

    scratg.bld.reddd



     
  8. richirich

    richirich New Member

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    Well today i got my new head stids and head gasket today from SBP. I was suprized at how stiff the new head gasket was compared to the one that came with the motor. upon comparison i noticed the original was easily bendable and i guess from the torque had expanded into the cylinder and must have been brushed by the piston cuz there was a wjde flat edge around the inside. So i think the cheap hg is just another part that should be replaced right away.
    So i went for about a 2 mile ride and im impressed with the smoothness of the motor and the power. It takes everything i got to not just open it up. i know that is not a good thing since its not fully broke in, but just cruizing around at quarter throttle is enough to get you going pretty good.
    I can say that im happy with the motor.
    in about 20-30 miles ill post how its still doing
     
  9. Greg58

    Greg58 Well-Known Member

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    On anything made of steel I use my air die grinder with a carbide raspe, makes short work of any exhaust flange porting.
     
  10. gera229

    gera229 New Member

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    What is the difference between the Grubee GT5 vs GT5-A and aren't CNS Carbs that they come with crap? They have the V2 CNS carbs by the way. Aren't NT Carbs better?

    Also the Phantom which is 58cc is worth more, but why is it more expensive? Is it worth it?
    Is it more reliable? Faster? Does it vibrate as much? Compared to the GT5(A) 66cc motors.
    Which motor do you like better?
    Which motor is better?
     
  11. greentek

    greentek New Member

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    Dislikes! The difference is the GT5A Has 6mm head studs instead of 8mm. WHAT!
    Dislikes! The Intake manifold is larger only on the end that Connects to the head, I don’t like it. Why? Its too long of a manifold and you cannot fit other short type, high performance manifolds on the head. They don’t make a short one for this size head.
    Likes! It has a high compression head for more power w/ 6mm studs, (not good).
    The engine seems different then the Gt5 engine, lower Quality.
    I like the GT5 w/ the CNS Carb Better!!!
     
  12. greentek

    greentek New Member

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    As for the CNS Carburetor, They work great, lots of POWER fast starts, they are the New edition to this league type of engines. The problem I think many people are having is?
    1. Understanding the Choke! Controlling the Choke Handlebar Lever.
    2. Idle Problems!
    3. Adjusting the needle pin on the Slide and the air fuel mixture screw.
    4. Only make Adjustments after its reached the operating temperature.
    So!!!
    1. The choke lever on the handlebars, when the cable is pulled, its! Choke ON.
    I found when its cold you turn it on or the cable all the way pulled and it starts 1st time. Let it idle. If you turn the throttle it might stall. So turn the choke lever down to half on, or only ¼ On. So, I found it ran great at choke On about ¼ -½ ways On as it warms up or turn it down as it warms up but not all the way off till its warmed up. You might find yourself running the choke On about ¼ On for a while till it warms up real good.

    2. I found that the throttle cable sticks and the slide sticks! So I took the cable off the slide and I use WD40 w/ a red straw and lube the Throttle cable real good then I found that the spring on the slide needs to be pulled just a little, don’t stretch it too much maybe about a ½ inch or ¾ inch. Then assemble it back together.

    3. After it reaches operating temperature, Then turn the choke off or cable not being pulled on the handlebar choke lever. Also, if the lever does not stay in the position you set it at, tighten the screw on the choke lever, use lock tight.

    4. Now set your idle screw turn the idle screw that controls the slide.
    Then adjust your air fuel mixture screw. If it has good bottom end power and too rich on full throttle then you may need to move the C clip on the slide needle pin up! (Make the neddle pin longer is leaner)
    Move the C clip up one notch to lean it, put it back together. Drive it!
    Adjust the air fuel mixture screw. Test it again.

    Also if the engine does not have 2-4 tanks the break-in period you might not get the good power yet.
    They always run better after break-in. After break-in fuel ratio changes. 4oz to 1 gal gas.
    I use synthetic 2 stroke or 2 cycle oil w/ 91 high Octane Gas and I had problems w/ gas that has ethanol cut or what is it 10% corn stuff? never again.
    Hope this helps someone!
     
    #12 greentek, Sep 14, 2011
    Last edited: Sep 14, 2011
  13. richirich

    richirich New Member

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    So far im liking the motor, i replaced all the hardware from the beginning. grade 8 head bolts and all socket head cap screws. the rest of the stuff i just switched over from my other motor (jaguar cdi, performance carb, pro-pipe) the intake on my other motor was the 40mm intake. it is tapped for dual boost bottles( i dont care what anyone says ,it cut down my high rpm vibrations)
    You mite not have researched but they do male the billit MM intakes,tapped and untapped, Piston bikes will have them this week. I called ManicMechanic.
    I have not had a gt5 to compare it to but i am more than satisfied with the power this motor makes and im still on 20:1 break in oil
    But like ive read in this forum a hundred times. "every motor is really just a crap shoot ,some good- some bad"
     
  14. bairdco

    bairdco a guy who makes cool bikes

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    my buddy brought the bike back sunday, same problems, blown head gasket.

    head was warped again, and the spark plug was loose, which i thought was pretty strange. i had put an ngk in with anti-seize on the threads, like i always do, but somehow it loosened up.

    tightened the plug, sanded the head, and installed 2 headgaskets, hopefully to lower the compression just enough to stop them from blowing.

    overall, i'm disappointed with this motor, and with the standard gt5, and anything else that comes out of the skyhawk factory, and i'm pretty much at the point where i'm not going to build anymore bikes for sale until there's a motor available that's more user friendly.

    if it was my bike, i can work out all the problems until it's right, but having a customer/ friend call me every week saying "my bike's broke again..." and then having to stop what i'm doing to fix problems that grubee failed to address when they built the motor, that's no fault of the customer, but due to lack of testing, quality control, etc, is a waste of my time and money.
     
  15. Greg58

    Greg58 Well-Known Member

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    I hate to do rework, but its even worse when it not something I did wrong. That why I have "helped" my friends build their bikes instead of doing it myself, I have only built two types of kits grubee and bgf. Both are sorta basic engines.
     
  16. mapbike

    mapbike Active Member

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    All three of my bikes run great now, have all the bugs out of them until the next one hits of coarse......LOL!

    But as to building and selling the MB's, I have had several people tell me that I should build some up and sell them, I haven't done it because of the exact reason Baird just described, many or most of the people that will want to buy one are people that couldn't build one themselves and IMHO that is a big wreck looking for a place to happen for the builder, these bikes need special attention for them to be even half way reliable and fairy trouble free, mine are pretty trouble free, I just look everything over real good listen to the engine as it warms up for any odd sounds, pay close attention to how it is running when I take off and then I just go on about as long of a trip as I want without a glitch once I confirm all is well.

    It takes a certain level of skill and understanding of the entire machine inorder to accomplish what I just described and the average not so mechanical person lacks these skills and the understanding of the machine beyond what they can just see, IMO these are best suited for knuckle busters, gearheads, mechanically inclined hobbiest or someone wanting to learn soem mecahnical skills, NOT the average Joe who just wants a neat toy or someone looking for reliable transportation.

    I said all of this to say that Greg58 has the right idea in just helping a friend build his bike and then you know that their interest are such that they're going to be the ones who will be tinkering and learning to repair their MB instead of them being an unsatisfied customer who will be driving you mad with all the little things that are so common to go wrong with these cheaply made China-lume-engines......

    If I build anything to sell it will be friction drive set ups with a more trouble free engine, unless the person is someone I know very well and they are willing to do their own fixing and learning with the free advice I'm willing to give when they need it from time to time, but even then I will point them to this forum for getting most of their questions answered so I dont get hounded to death all the time........LOL!

    Just my $0.02 nothing more......

    Peace, map



    .wee.
     
  17. Tohri

    Tohri New Member

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    Mapbike, you're 100% correct there.

    I mean I even get irritated with the people who want their $200 bike kit to go 50 miles an hour, but don't even understand what the carburator Does. But they know they need an aftermarket one, right away, because THAT'S the problem, obviously.
     
  18. richirich

    richirich New Member

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    I can understand what your saying, but it is not true with everyone. I consider myself somewhat mechancaly inclined. I have built a really nice bike. i have gone thru alot of trial and error. I have done all the standard upgrading i could possibly do beside actually taking the case apart and grindind out ports and messing with the piston. I have spent days reading all the posts on this and it is still overwhelming for someone who has never seen it done. the post ive seen on it dont really say what exact motor there are doing it to and everybody seems to have their idea on whats right.
    Having a motor with this work already done to it, i would have more confidence in doing my own motors like it. Im kinda looking at it like how many motors and top ends would i go thru before i got it right?
    I am thinking this winter when washighton is snowed in ill just buy a few motors and experiment with all the porting and transfer ports and pistons. hopefully i wouldnt screw them all up.
    Anyway, just buing a 400$ motor and copying from there seems like an easier solution.
    But then again nothing ever seems to be easy...
    at least ill have something to do this winter..
     
  19. mapbike

    mapbike Active Member

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    richirich,

    What you just said below is the point I was making when I said this in my post

    Quote: mechanically inclined hobbiest or someone wanting to learn some mechanical skills, NOT the average Joe who just wants a neat toy or someone looking for reliable transportation.

    What you just said describes a person with some mechanical skills as you said and someone wanting to learn more than you already know by making the MB a cool educational fun hobby project....... You are the kind of person I was speaking of as an acception, anyone I know that is a person like you say you are, I would gladly build a bike up for if they wanted me too and I had the time, you are one of us and NOT the pain in the neck kinda customer many would be that I was speaking of.

    I would suggest just getting one extra engine, for the winter project you spoke of and here are some links to where you can get most everything you will need to clean up the ports and ploish up all the rough edges on that project engine if you dont already have all the stuff.

    Widget Supply: Burrs and Cutters

    Widget Supply: 1/8 x 1/2 inch Bands & Mandrels

    Widget Supply: 1/4 x 1/2 inch Bands & Mandrels

    Widget Supply: Carbide - Bud

    Widget Supply: Carbide - Cylinder - Square End

    Best wishes on the project and I hope you get it done just like you want it, just be patient and ask lots of questions here when needed, many very knowledable fellas here that help us out all the time.

    Peace, map



     
  20. greentek

    greentek New Member

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    Conclusion!!!
    On The GT5-A Super Hawk????
    The head and piston Body is set for high compression, So why do they put 6mm head studs? It needs 8mm.

    The Head has small fins so no matter how many head gaskets you use it gets too hot!!!

    After 10-15 minutes and does not operate normally and I think this is a bad design or manufacture defect. None of my engines ever ran this hot or done this.

    I ran it rich and used a cold plug. W/ 2-3 head gaskets still runs hot. The head sucks.
    My Conclusion is the GT5-A is a pile of crap don’t waste your money.
    Go ahead and find out for yourself you will see that I am right.

    The 2011 Original Gt5 is a great set up and comes w/ 8mm head studs, and a nice head.
    I wish they would tell you the detailed specs on the engine before you buy it instead of a dice throw or gamble of what you are going to get?
     

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