loss of engine breaking

Discussion in 'Engine, Fuel and Exhaust' started by Zippster, Mar 8, 2012.

  1. Zippster

    Zippster Member

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    I just had S&S 509 gear cams installed on a 2002 88 FXDL. the bike runs nice, however i do not get the engine braking on decell that i used to. I am thinking the guy fooled with the carb and the slid is not coming down as fast, but I am not sure. I do not thing the cam would cause this. I am thinking of hitting the kill switch and see if it decels it would probably rule out the cam. Any suggestions?
     
  2. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    I would not hit the kill switch just yet. This could be throttle cables that are not routed correctly. I assume you have the stock CV carb, and since the bike is running well it seems your mech. has it jetted correctly. The slide movement is achieved by negative pressure when you open the throttle plate with the twist grip. Rising and lowering the slide happens when you open and close the throttle plate (butterfly). If the throttle plate is slow closing the slide will be slow closing. Take off your AC and raise the slide with your finger, twist the throttle and let it snap back with the spring. The throttle plate should snap closed. If it hangs up try moving your cables back and forth to see if they are binding. You also may need to lube the cables. I would try this first to eliminate the cables as a problem.
     
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  3. Jack Klarich

    Jack Klarich Expert Member

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    As Don mentioned have a look inside the air cleaner at the action on the slide, does it idle OK and rev up OK, returning to idle normal?
     
  4. Zippster

    Zippster Member

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    Thanks guys, I will try that. It is a stock CV. I pulled off the top cover just to check the spring and diaphram all looked ok.

    Yes other than the loss of engine breaking it runs normally, idles fine. I agree its probably something simple, hanging up. the cables do not stick or feel abnormal either.
     
  5. dbmg

    dbmg Experienced Member

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    This is info from S&S: S&S Cycle Complete Gear Drive Camshaft 509G Cam Kit
    • The S&S Camshaft Gear Drive Kit increases valve timing accuracy in 1999-2006 Twin Cam 88 engines by eliminating timing chain lash and the loosely fit stock cam gears
    • This is accomplished by replacing the stock cam drive sprockets and chain with light press fit S&S gears

    • Because the chain, chain guides, and tensioner are eliminated, there is no longer a possibility for these parts to fail and damage other parts

    • The S&S Camshaft Gear Drive Kit reverses the rear cam's direction of rotation, providing additional operating clearance between cam lobes

    • As a result, higher cam lifts are possible with the gear drive kit

    I am wondering that with the lift of the cam, and rest of engine stock, the advance that the cam creates is it possible????? That cam advance is to cause power under load which would alleviate engine breaking on decel????
     
  6. HDDon

    HDDon Experienced Member Contributor Retired Moderators

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    Good point! I also noticed that after the gear drive was installed there was little to no resistance when turning the motor over by hand (without spark plugs). The motor is not having to turn the cam chain with the tensioners. So there is not as much resistance on the crank.
     
  7. Zippster

    Zippster Member

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    At first i wondered if the cam timing change would cause this, but it advertises 180 PSI cranking pressure. There is a reduction in engine friction with the gears, but I would think that the ring friction and compression is still enough to feel the decel. I will ride this weekend and do a little experimenting.
     
  8. BUBBIE

    BUBBIE Well-Known Member

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    You should FEEL compression like before. UNless the air/throttle and idle is "UP".

    The 509 cam si a small duration cam open and close of the valves are NOT going to leave No compression..

    Something has changed from the set-up before that is making it NOT feel the slowing of engine compression....

    Are You Sure that one or more valves are NOT too tight and staying open on the intake or exhaust valve a little allowing the Jake effect of Loosing compression?...

    I would check the settings on the Hydraulic lifters to make sure the Positioning was correct when the lifters were adjusted.... Easy enough to do and re-set.

    I assume you have adjustable push rods installed?

    ???? Have you tried the switch off(but DON'T turn it back on until completely dead and start with starter) Squeeze clutch in and let motor STOP, after you compare. DO You feel a difference?

    signed....BUBBIE
     
  9. Zippster

    Zippster Member

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    Bubbie

    No stock push rods. All good questions and comments from everyone. It has good power and no poping or caring on that would make me think one of the valves was remaining open, however I do not know that. I think the first test is the kill switch which i have not done yet and I agree i will just do it and bring the bike to a stop pulling in the clutch and restart with the starter. I will find a place that i can do it safely.

    Zippster