Discussion in '2-Stroke Engines' started by KCvale, Jun 22, 2010.

  1. KCvale

    KCvale Motorized Bicycle Vendor

    Are you talking about Skyhawk motors? Becaue the ports seem pretty low to me.

    This is my 66 with a little sticker misprint ;-}


    I was looking at your ported pic 21006, it looks like a straight shaft, how can the carb fit? There is only about 1/2" it can go down before hitting the clutch cable and it can't go down at all with the air cleaner on, it already touches the seat post.
    Or does the shorter tube allow it to fit?

    And for my 48, I mounted it in a tough build with a jackshaft.


    I have zero room to move the carb anywhere, so I guess there just isn't anything I can do with them?
    Last edited: Jun 22, 2010

  2. KCvale

    KCvale Motorized Bicycle Vendor

    Thanks for the heads up guys.
    I read through all the great articles here and on MotorizedBikes about porting and it seems straight forward and logical to me.

    I have 2 new Grubees here so I am going to give it a shot myself.
    The hitch is I don't have a Dremel. I do however have a spiffy little drill press and some cool bits that I think would do a good job pretty quick and easy.

    I'll post a little a topic about it, or add to one here about porting if it seems to work out well. With pictures of course ;-}
  3. GearNut

    GearNut Active Member

    Porting with a drill press!??!! :eek: That's a new method I haven't heard of yet!
    It sounds like you will need an even steadier hand.
  4. KCvale

    KCvale Motorized Bicycle Vendor

    I don't know yet, just adapting to the tools I have.
    I won't be doing anything to the cylinder with it, but it should be a breeze to use on the intake and exhaust ports.

    I'll put some pics up when I start as I will using that same blown out tailpipe to test on.
  5. Stan4d

    Stan4d New Member

    Please add to an existing thread. That is how we can keep all the info in one place. It also makes the subject easier to search. Help your fellow MBcr's out.
  6. KCvale

    KCvale Motorized Bicycle Vendor

    Will do stan, I made and operate multiple we sites like this about different things, "all in one place" is a good thing ;-}

    I got a new sale yesterday and going to port match this SkyHawk 48cc before I drop it in the GT1 bike without using a Dremel because, like a big vice for bending tailpipe, I don't have one.
  7. KCvale

    KCvale Motorized Bicycle Vendor

    Wow Jim, your example is a motorcycle with pedals! Very cool.
    And I agree with you about having the interest, funds, and skills to make anything new for sale.

    All I have done is my ignition system upgrade and it took a lot to make it a product.
  8. Thanks KC,

    I saw your keyed ignition on another thread...nicely done!

  9. KCvale

    KCvale Motorized Bicycle Vendor

    No harm no foul ;-}

    I tried my drill press, no joy. There is just no bit for grinding that thick of steel.
    The Dremel tools and available bits looked like a joke to me, I didn't see any carbide steel grinding attachments and those stone ones look like they would wear out before you could do 1 pipe.

    While browsing I did however find this tool.


    It looked so promising I bought it and an air compressor and the whole hose/fitting kit.


    I fired up the compressor and gave it a try and it ran out of air in like 5 seconds.

    In short the compressor can store 100 PSI but can only put out about 40 continuous, and the air file needs 90 PSI.

    I'll give it a shot at the tire store tomorrow but from what I seen it looks like the perfect tool to make short work of filing the tailpipe inside to match it better to the cylinder port.
  10. KC,

    That air file does look promising!

    I haven't spotted that air file in our local store, but I will look for it next time I'm there. That has ALL kinds of possibilities in the shop in addition to porting.

    Unfortunately most air tools are; air hogs. When I set-up my shop I bought an old Quincy, 1961, 20 horsepower compressor. It is more than I need, but we never run out of air...:wink:

    Pro porting tools are pricey:


    I use the air version of these. They are between the large die grinders that you typically see at the stores and dental tools.

  11. Stan4d

    Stan4d New Member

    Try investing in a compressor that holds more than 10 gallons....even if the compressor cannot keep up, it might give you enough to do the job.
  12. Fabian

    Fabian Well-Known Member

    Generally you don't need an industrial sized air pump to run most air tools, as you're not using them for long periods of time.
    My solution is two 3hp air compressors with an additional four "100 litre" receiver tanks.
    This combo allows use of a 45cfm 8 inch air angle grinder for about 1 minute before the pressure drops away to an unusable level.
    Remember, that's a 45cfm air tool and 1 minute of grinding gets a lot of work done.

    With one compressor going, it takes about half an hour to pump up all the tanks to 140 PSI.
    Most air tools use between 15 and 30 CFM.

    The other advantage of having so much air storage is for cleanup duties.
    Running an air line from both compressor receiver tanks into a junction that exits in a half inch outlet with a ball control valve, dumps around 700 litres of air in about 30 seconds, blowing every manner of dust, metal filings, and anything else that isn't bolted or nailed down to the work bench, flying out the garage door and into the next door neighbours back yard.

    Very convenient for cleanup purposes.