Twin Spark Plug Cylinder Head Prototype!

Discussion in 'Performance Mods' started by crmachineman, Oct 24, 2012.

  1. crmachineman

    crmachineman Member

    Hi everybody.
    I've been heavily messing around with these 2 stroke motors, and I just joined this forum. I've been on one of the other forums for a little while, and thought you folks over here would appreciate some of my tinkerings.
    Anyway, this is actually not the first prototype, but it's the first "production" model.
    As you would first suspect; twin spark plugs need twin ignition.
    It's true, but this is not very difficult to overcome.
    I've included some photos of the components I used to deal with this challenge.
    I decided to use a DC fired CDI from a 50 cc GY6 scooter(I believe) They seemed like a pretty common unit, which I found readily on ebay.
    It being a DC fired unit, I had to bring a battery along, which is the part of this system I like the least, especially my awful electrical tape mounting system!
    I didn't see much way around the problem that the original magneto wouldn't have enough energy to supply two spark plugs with a hot spark.
    With the battery, there is plenty of energy to go around, and a single CDI unit seems to reliably power both coils to deliver a blue spark, much more powerful than the stock ignition system can deliver.
    If you look at the head, you will see the compression release. So, yes, there is a third hole, just like the spark plug holes. It is definitely a deluxe set up. I think I will make them in two versions; some with three holes and some with only two.
    When they become available, which should be in a few days, I will start a thread in the vendor area here at this forum. There, you will be able to check out cost and availability and such.

    So, thanks for having me aboard. I will try to adhere to forum policy to the best of my ability.
    Thank you!

    Attached Files:

  2. Fabian

    Fabian Well-Known Member

  3. Fabian

    Fabian Well-Known Member

    From what i understand the threaded diameter of a chainsaw decomp button is 8mm - very compact, very simple and very reliable.

    The inside of the combustion chamber only sees a 1mm hole for a chainsaw style decomp, thereby preventing any metallic parts from falling into the combustion chamber if the decomp would ever fail - an important feature.
  4. crmachineman

    crmachineman Member

    Hi Fabian.
    Well, the head is designed to be used with a larger decompression valve. All three holes are machined the same; 14MM x 1.25 thread.

    I was able to find a decompression valve kit which uses that thread on ebay. I think you would really want to have a good rugged one with a cable release so you can operate it while driving.

    If it becomes really hard to find those kind of decompression valves. I will probably make a small production run of those valves.