QUESTIONS: Engine Porting, 110cc ATV Exhaust, Frame Strength PICS

Discussion in 'Performance Mods' started by slaquers, May 5, 2010.

  1. slaquers

    slaquers Member

    Looking for machinist to work with me on the motor - PM please.

    Uploaded with - Whole bike BEFORE PAINT/RESTORE - Frame - AFTER PAINT! Looks good to me! Still need to replace tires/tubes/chain

    Picture of the bike I am building, in process of painting. Huffy frame. No rust on frame, sanded/primed/painted fenders and handle bars, greased everything, could use new bearings - got new tubes - not sure on tires. Will be a commuter "scooter".

    Bought a 66cc "Skyhawk" (I think its from Chinagas or w/e) for $150 for kit. (sponser link "KingsMotorBikes" Any good?)

    Next bike - trail/dirt bike (very very nice bike, a GT frame and all components). Want to ask questions mainly about this bike.

    /end intro

    1. I have a cheap exhaust from a 110cc ATV, can I use this, I can get pictures/specs. If not, whats the CHEAPEST way for me to get an OK exhaust on it.

    2. I want to port the engine, at least the intake or w/e - is there a guide to this.

    3. I want to port the engine to like 72-80cc? Possible? If so does anyone here want to make some money machining the head? PM's?

    4. The frame, how much speed do you think the frame can handle? (I know the GT can handle anything...not sure on Huffy)

    5. Performance carb - where to get or how to build? Just bigger jet or what?

    Sorry I am new to these small engines, have some general automotive knowledge and since they are so cheap I figure why not have a blast while they last (on trail bike...HUGE backyard )

    Also can I use this as my build thread and get info as I go or how does it work, kinda new here been lurking a while posted a few posts, just got to my build.

    Last edited: May 5, 2010

  2. loquin

    loquin Active Member

    it really works much better if you attach pictures, instead of posting links to them. When you post links, it makes the content at this site dependent upon the other site where the images are hosted. If for ANY reason, those images later become unavailable, this site 'loses out.' :(

    In addition, if the pictures are too big, it can make for a miserable slow page refresh, especially if the viewer is connecting through a dialup line...

    It's very simple to attach files: when posting, make sure you're in the advanced editing mode: Below the main body of the edit window is a button labeled 'Manage Attachments.' Clicking this button opens a pop up form. You can browse to the pictures on your computer (up to 4 at a time) or, you can paste the URL of the picture into the 'Upload File From URL' textbox, and upload the image that way.
  3. GearNut

    GearNut Active Member

    Porting does not increase the engine's displacement, so you will never be able to port your 66cc up to a 72- -80cc size. Porting only increases the engine's efficiency at a particular RPM range.

    If you think that you can get the ATV exhaust to bolt up to the cylinder then do it. I do not recommend modifying the cylinder though, only modify the exhaust if necessary.
    You will be far better off using a tuned exhaust (expansion chamber type) that a few vendors sell. If none of that will work then.....
    The CHEAPEST way is to get a used stock exhaust from someone. Ask around here, you may get lucky.
  4. slaquers

    slaquers Member

    That site will not go down, personal/business site.

    Anyway, yea the pics are huge etc. But heres an update:



    On ATV exhaust, gonna take a look at it tomorrow if I don't like its look I will find an old looking one, I want the classic look with this thing, rough n dirty on my GT.

    As for porting, okay did not know it didn't increase size - but what do you recomend? I will have tools and saddle bags on this bike but still want to hit 35 with decent acceleration (Virginia traffic/drivers...). Perf. carb, expansion pipe, ported exhaust manifold/intake or w/e with dremel?


    Should I rr-do all my gaskets on this Chinagas skyhawk clone from KingsMotorBikes (sponsor).
  5. slaquers

    slaquers Member

    bumpage...anyone? ^^ above questions...
  6. GearNut

    GearNut Active Member

    Dude, do a search on this site for porting. It can get complicated very fast and the previous posts cover it well. I would end up pulling out my hair getting into describing the fine details that have to be adhered to when doing a proper port job. There is alot more to it then just merrily grinding away at the holes on the cylinder.
    I can't recommend a perf. carb as I have never ran one. I like my engines to last, not haul a--.
    I hear more happy reviews concerning the pipe that Pirate Cycles sells than any other vendor's pipe. Some folks like to use pipes made for pocket bikes too.

    Here's a search I did concerning porting:

    Have fun and above all, go slow and careful when modding your engine.
    It it better to creep up on your target then it is to blow past it. Metal is much more difficult to put back than it is to remove it. :)