Another 99cc Predator build

Discussion in '4-Stroke Engines' started by jbcruisin, Jan 15, 2012.

  1. jbcruisin

    jbcruisin Member

    I got an engine. All this talk about the 99cc Got me convinced to buy one. It's going in my blue bike. it has a 49cc Hua Sheng in it now.
     

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  2. jbcruisin

    jbcruisin Member

    Pictures!

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  3. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Jay,

    Just a quick note about the bolts needed to mount the Q-Matic as they are somewhat different than you would suspect. They are 5/16' X 24 [fine thread].

    After looking at your pictures, it might be wise to upgrade the bolts in the motor mount to a larger size, as the 99 CC motor is a lot heavier than the 49 CC. If 6 MM on the plate [side] use 1/4" X 20, and consider replacing the long 6 MM end bolts with 8 MM or 5/16".

    Motor sure is mounted low, and should be a great ride because of the lower center of gravity.

    BTW, the motor is very strong with a tuned flex pipe. It needs to be 3.5" longer than the tuned system on the 49 CC motor. The slightly longer pipe takes advantage of the torque curve of the 99 CC motor, and still extends the RPM range near 6000.

    Might want to put a Tachometer on the setup, as I don't think the part plastic flywheel is too happy running above 6000 for an extended period of time [mine wasn't].

    Sure looks to be a sharp looking ride!

    Have fun,
     
  4. chainmaker

    chainmaker Member

    Way to go Jay !! Sure looks at home in that bike.
     
  5. jbcruisin

    jbcruisin Member

    Thanks guys & I have a tach on it. :)
     
  6. jbcruisin

    jbcruisin Member

    Soon ready to install it all. here's some pics of engine & drive stuff. The drive came out of the blue bike I posted a pic of in the first post & was attached to a 49cc Hua Sheng.

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  7. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Jay,


    Make sure there is clearace between the clutch hub and the valve cover. If the clearance is minimum it might rub the valve cover as the clutch hub [bell] floats on the output shaft.

    Lookin' good!

    Have fun,
     
  8. jbcruisin

    jbcruisin Member


    It's close but okay :)
     
  9. jbcruisin

    jbcruisin Member

    I finally finished it yesterday. Took it for a short ride & it seems to have plenty of power.

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  10. jbcruisin

    jbcruisin Member

    Here's a pic of carb linkage. Hope it's clear enough to see.

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  11. MikeJ

    MikeJ Member

    Hi jbcruisin, Quenton -

    That is a very nice design and a good choice of frame and engine combinations. It just "looks right" and you will get a lot of miles out of it before something needs attention. And it probably will not be the drive train.

    Just a quick question, I don't recall seeing this: At what engine RPM does the clutch lock in? I may re-spring mine to avoid the "pulsing" I am feeling at low RPM acceleration. (I am not using Quenton's fine product, but one of my own designs that takes advantage of a jackshaft and the rear cassette gears.)

    Thanks,
    MikeJ
     
    Last edited: Mar 4, 2012
  12. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi MikeJ,

    The Q-Matic drive uses custom designed primary ratios and the clutch "ticking" and "lock" speeds are lowered to work smoother. The stock Q-Matic drive used on the 49 CC motors spin the clutch at 723 RPMs at idle [2000 RPMs]. The HF version of the Q-Matic spins the clutch at 533 RPMs at idle [1100 RPMs]. If you have the clutch mounted on the motor crankshaft, it will be difficult to totally remove the "pulses". In order to reduce the "pulsing" you will need to determine the cause....
    Is the gap from idle to "ticking" narrow or wide?
    If the gap is wide the spring needs to be weaker, if the gap is narrow, then a stronger spring is needed. Most often the spring needs to be stronger, as the shoes tend to kick in and out at lower RPMs if the "ticking" threshold is close to idle.

    Have fun,
     
  13. MikeJ

    MikeJ Member

    Hi Quenton -

    Thanks for writing. You gave me some ideas for a new modification to my drive train. I wonder if I can move my centrifugal clutch to the cassette side of the bike. That may give me a little more flexibility for gear ratios. It's time to experiment some more!

    MikeJ
     
  14. jbcruisin

    jbcruisin Member

    Today I took it out for the first real test ride. I opened it up & it went up to 46 mph easily. It was doing 6000 rpm's according to my "Tiny Tach". Goes great up hills. I'm very happy with it.
     
  15. Quenton Guenther

    Quenton Guenther Motored Bikes Sponsor

    Hi Jay,

    6000 RPMs is about the max on the motors we are testing at the factory level.

    Try resetting the primary adjustable pulley [larger] to reduce the RPM level. I have managed to get one of the factory test bikes to exceed 50 MPH with the front pulley set at 3.1". The final ratio is 8.76 X 1 with the front pulley set at 3.1", and hit 50 MPH at 5675 RPMs.


    Have fun,
     
  16. MikeJ

    MikeJ Member

    30 mph is my upper limit; I'm a conservative type. Tech specs make that engine sound pretty durable. Let us know the conditions of your riding and how that engine and Q-matic drive performs. Maybe more readers will convert to this 4-stroke combination....
     
    Last edited: Mar 10, 2012
  17. jbcruisin

    jbcruisin Member

    I'll be playing with that pulley to get the best performance :) It's tightened about 1/2 way out now.
     
  18. jbcruisin

    jbcruisin Member

    Here's a picture of the 3/4 inch electrical conduit strap that I used for the top drive mount.
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  19. brizzle9725

    brizzle9725 New Member

    Engine mount

    Can someone explain to me how to go about making a mount for the 99cc hf engine? I don't know how to weld either. Thanks in advance!
     
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