Yet another Reed Valve conversion.

Discussion in 'Performance Mods' started by FelipeCobu, Sep 20, 2012.

  1. FelipeCobu

    FelipeCobu Member

    Hi everyone,

    I was working on a conversion for the China Girl (piston ported) to reed valve.

    Since the most common moped engine here in Brazil is the MBK AV-10 i got one
    reed block from it and started molding some kind of adapter to fit it on the intake
    of our "beloved" crappy engine.

    By this time I already got the molding casted on aluminium I do have now to do some gaskets
    and some porting.

    Here are the pics:

    2012-09-20 15.26.33.jpg 2012-09-20 15.27.28.jpg 2012-09-20 15.27.11.jpg 2012-09-20 15.26.48.jpg

  2. jaguar

    jaguar Well-Known Member

    What is the length and width of the reed petals?
    Don't forget to drill holes in your pistons intake skirt.
  3. FelipeCobu

    FelipeCobu Member


    I inlet before the petal is a square with 11mm side, the petals measure 15mm x 50mm.


    Felipe Cobu
  4. jaguar

    jaguar Well-Known Member

  5. FelipeCobu

    FelipeCobu Member

    If I do need a bigger reed valve I can probably use an Yamaha RD135 reed block.


    All I have to do I mold another adaptor and then cast it on aluminium.

    Felipe Cobu
  6. jaguar

    jaguar Well-Known Member

    I have ideas for enlarging the intake but have never worked with aluminum and don't really know how to proceed. A local welder here welds broken mirror holders made of aluminum back onto motorcycles but I'm not sure he could help construct a new aluminum intake that a reed valve could mount to. The 50cc that went 150mph at Bonneville used a 28mm carburetor so obviously size matters. Unfortunately in our case there is very limited transfer area and so probably the only option is using a boost port that deepens and widens the father down the piston moves.
    How is your conversion coming along?
  7. jaguar

    jaguar Well-Known Member

    I am brainstorming now because JNMotors wants me to make them a firebreathing 66cc engine to win at the races. I think with a slightly opened intake with a Rock Solid reed valve we could win (mostly because of my torque pipe) but I really want it even better.
    I am thinking about torching off the existent intake tract, tapping 4 mounting holes into the cylinder there, mounting a custom made reed valve connector, and using a reed valve with much larger flow area than the Rock Solid. That all in conjuction with a 18mm carb.
    Last edited: Sep 26, 2012
  8. FelipeCobu

    FelipeCobu Member

    I don't work with the castings itself, I made the molding then payed a company that work with artistic castings (trophy, medals, and things like this),
    and they "sand cast" the piece to me. Maybe you can create the mold using wood, resign, or even a 3d printer.

    I didn't had time to work on the conversion will have to go to my friend's show to use his drill press and buy some steel pipe and hose to adjust my intake tube.

    I'm going to post pics of my progress.

  9. FelipeCobu

    FelipeCobu Member

    You also can have your reed block connector made out of aluminum sheets then someone that works with intercoolers and radiators can create one.
  10. MotorBicycleRacing

    MotorBicycleRacing Well-Known Member

    I am looking forward to seeing JNMotors give Arrow Motorized Cycles some competition.

    Are you going to have the bike ready for the October 20th race?

    PS: Arrow Motorized Cycles uses a 24 mm Mikuni on their reed valve setup.

    Last edited: Sep 26, 2012
  11. jaguar

    jaguar Well-Known Member

    It will be hard to make that deadline but I will try.
    When I was talking to Dionel of JNMotors I told him; "You are mentioning every hop-up except the most important one. Every item you mentioned can only give a max of 10% power gain, whereas the one thing you are overlooking can give 50-100% gain- the expansion chamber! And all the pipes available for this engine are completely wrong for it because they only offer a narrow powerband, whereas a single speed ride needs a very broad powerband which also holds true for racing since all the riding (except for the start) is done from half to full speed. With my torque pipe you will leave them all behind at the start and then exiting every turn you will gain even more distance. After one lap you will have to stop to look and see where your "competitors" are. ha!"
  12. Easy Rider

    Easy Rider New Member

    I'm looking forward to meeting you and seeing your beast on the track Jaguar. I understand the theory on center bleed pipes and you do make a good point. Everyone who was competitive used and raced with them during the ISA go ped days. They used them mainly for the torque they produced coming out of the corners. It will be cool seeing you give those guys a run for their money at Grange. The Pro China Doll class always has exciting and great races to watch.
  13. jaguar

    jaguar Well-Known Member

    I wish I could be there. I want to race my 55cc which I am confidant can beat any 66cc once I get the reed valve I want on it with a custom designed housing. But I won't because I live in South America and can't really afford the $1500 round trip.
    But it sure would be fun to astound all those 66cc owners with what a torque pipe can do. Also I just found out that JNMotors is taking their time and aren't planning to have the final JNM/Jaguar bike ready till next year.
  14. Easy Rider

    Easy Rider New Member

    Sorry you won't be able to make this race. $1500 for a plane ticket is a lot for anyone to spend for a weekend of racing. Hopefully you and JNMotor can get the bike done for next year's season.
    The HT motors have come along way since last year. They are running lap times close to my times plus the guys racing them are really fast.
    Good luck and hope to see you next year. If you can't make it out, you should find a local racer to race for you guys.
  15. FelipeCobu

    FelipeCobu Member

    Finally got some time to work on my reed valve conversion, by this moment I already have the reed adaptor attached to the jug, and already made the engine run. But I need to create a new intake tube and re jet my carburetor. Follow some pics off the work. As soon as I get it tune will make a video and post my impression, but seens like it haves much more compression and the noise changed a bit too.

    2012-10-12 15.47.59.jpg 2012-10-12 19.14.08.jpg 2012-10-12 16.47.12.jpg 2012-10-12 16.46.59.jpg 2012-10-12 16.46.39.jpg
  16. Fabian

    Fabian Well-Known Member

    Have you checked out the Rock Solid Engines CNC Billet reed valve intake.
    It's such a jewel like piece of work, not only aesthetically but dimensionally, as it's extremely compact and fits inside the intake port; effectively reducing crankcase volume and boosting crankcase compression compared to an externally located reed valve system.
  17. jaguar

    jaguar Well-Known Member

    yeah it sticks slightly into the intake tract but its flow area is very limited. Its ok for poking around on the street though.
  18. Fabian

    Fabian Well-Known Member

    Exactly, it's perfect for riding around on the street, with an engine that has not been heavily modified, which suits about 98% of people involved in this hobby/transport.

    I can say the the Rock Solid Engines reed valve intake works terrifically well, boosting low and midrange torque and reducing noise, which in this day and age of draconian law enforcement is more important than the performance increase.