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Compression release

Discussion in 'Motorcycle Tech Talk' started by douglas, May 21, 2008.

  1. douglas

    douglas New Member

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    feedback on compression release valves for rev-tech 100,suggestions?
    douglas, May 21, 2008
    #1
  3. Art_NJr

    Art_NJr New Member

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    You can get simple "pop-up" ones from Zippers Performance.

    I have 'em on my 100" race engine, but even with the (a lot higher than a street bike) compression ratio, if the engine's tuned right & the battery is good, they're not necessary.
    Art_NJr, May 21, 2008
    #2
  4. jazzhog

    jazzhog New Member

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    If the engine don't start right up at the first crank, they are worthless. To install them I believe the heads have to come off. Spike make ones that fit with the spark plugs, I don't know how well they do the job. Art-Njr is right if you have a good battery and the scoot is tuned properly you don't need them.

    I had them installed on my Fatboy Then had to buy a strong battery anyway.
    I bought a big bore 350CCA and it has plenty of power to kick that sucker over. "JAZZ" :cool:
    jazzhog, May 22, 2008
    #3
  5. hotroadking

    hotroadking Super Moderator Staff Member

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    Have you done a compression test on the motor, cold?

    Check the PSI and see where you are.


    Where you get into starting issues is hot restarts, a high comp (ie over 195 per cyl) motor can kickback hard on restarts especially on hot fl summer days . my 205 psi 95 would start without releases cold every time, stock starter and ring gear.

    Hot restarts were a bit tricky had to learn how to start it hot.

    But it's not impossible to start, simply stay off the throttle don't twist it to add fuel like you do cold, no gas, no enricher, thumb the starter and let it turn over the motor to clear the cyl and then start.

    Typically you can get combustion from the higher pressures and pre-ignition as the fuel enters the combustion chamber and the very hot piston domes then preignition and kick back.

    Or if you have lifter bleed down where a valve ends up closing from spring pressure forcing the valve closed on a bleeding lifter, then you are sitting on the wrong part of the cam and the cyl is closed, really cranking up the pressure.

    SNS makes travel limiters you put in the lifters JMO a good idea on high comp motors with high lift cams.
    hotroadking, May 22, 2008
    #4
  6. SkyKing

    SkyKing New Member

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    There isn't a lot available for the thread size that the RevTech 100 takes. I don't remember who made them, but there is an old thread with the info. You just need to research the old threads a bit. Look back about 3-4 years.
    SkyKing, May 23, 2008
    #5
  7. SkyKing

    SkyKing New Member

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    SkyKing, May 23, 2008
    #6

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