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Higher Rocker Ratio

Discussion in 'Motorcycle Tech Talk' started by JohnnyBiker, Jul 9, 2014.

  1. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Once upon a time I remember thinking to myself that using higher rocker ratios was kind of pointless. However, now that I have found a cam that gives me the timing that I want and has decent lift but could benefit from a higher ratio, I now see why people do it. I mean why not, it doesn't change the timing event or power points, so what can hurt?
    JohnnyBiker, Jul 9, 2014
    #1
  3. hotroadking

    hotroadking Super Moderator Staff Member

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    Just be sure your springs are up to it and that the valve train has clearance
    hotroadking, Jul 9, 2014
    #2
  4. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Yep. It also helps that I am not running monster cams either.
    JohnnyBiker, Jul 10, 2014
    #3
  5. hotroadking

    hotroadking Super Moderator Staff Member

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    what cams are you going to run,

    I would suggest you go with SNS roller rockers, that improves
    the geometry because the rollers won't put a sideways pressure
    on the valve like a stander non roller rocker, it's easier especially
    when you increase lift and with the increased ratio rollers a must

    stay away from the cheap crap, there have been plenty of stories
    about broken roller rockers from chin lee sources like ultima

    Run american SNS or Jims,
    hotroadking, Jul 10, 2014
    #4
  6. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Most likely what I will do is send the stock rockers into Baisley performance in Oregon and have those converted to rollers with higher ratios but only on the exhaust side. I may be going a tad over board but I am seriously considering doing geometry correction on these, even though I am only using .575 Red Shift cams. I will be at .610" lift if I decide on the higher ratio.
    JohnnyBiker, Jul 10, 2014
    #5
  7. bambidee

    bambidee Active Member

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    I put S/E 1.725 rollers on my 94 evo and Crane 1.725 on my R/K with a feuling 534. side play was right on with both and not any more noticable noise. A cheap set are a disaster waiting to happen if the needle bearings go thru the engine
    bambidee, Jul 10, 2014
    #6
  8. hotroadking

    hotroadking Super Moderator Staff Member

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    Why not run a tw-9b 630 lift made for a big inch
    hotroadking, Jul 10, 2014
    #7
  9. JohnnyBiker

    JohnnyBiker Well-Known Member

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    I am using SE rollers in my 98. I like them a lot.
    JohnnyBiker, Jul 11, 2014
    #8
  10. JohnnyBiker

    JohnnyBiker Well-Known Member

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    Well for one I got these cams for really cheap. Once I start putting numbers into my software I will know more if I will use .575 or not. If I dont, I will put the .575 in my 98. Two. From reading, I am just not a huge fan of Wood's cams. I like silent valve trains. Sure they make power but I need this to be tolerable for long distances. Three. Because I don't want to.
    JohnnyBiker, Jul 11, 2014
    #9
  11. hotroadking

    hotroadking Super Moderator Staff Member

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    Good reasons, typically running oversized rockers is done
    when you've selected the wrong cam to begin with (ie the results
    do not bear out the power you expected) or if you can't run .630 lift
    cams without doing a lot of work to the cases for clearance reasons
    and the rockers can make up the cams short fall in lift.

    Remember they won't do jack for duration so if you add a lot of lift
    to a cam with an already short duration it's going to change the power
    curve significantly.

    You should also plug in +2 and +4 degree advance into the cams
    to see what happens, woods makes a cam timing gear that advances or retards
    the physical timing of the cam, it can make a big difference.
    hotroadking, Jul 11, 2014
    #10
  12. JohnnyBiker

    JohnnyBiker Well-Known Member

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    If you read my first post it says there that it won't change other aspects of the cam. Also I am really only looking to do this on the exhaust side if at all. I have a really neat computer program that will tell me within +/- 2% of what my power output will be and where it will be.

    Long ways to go.
    JohnnyBiker, Jul 11, 2014
    #11

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