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Thread: 748RS Heads

  1. #1
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    Default 748RS Heads

    Whats the story with the 748RS heads... do they go on a 888 Engine or not ?

    I know that they have some nice 36mm Inlet valves, but shorter stems? But do they share rockers, and the rest of it ?

    Grazie mille

    STIG
    Last edited by stiglarsenDK; 08-03-2017 at 02:09 PM.

  2. #2
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    I think they are like regular 748 heads as far as rockers and fitment. I put 748 heads on my engine years ago(standard 748 heads). Had to open the combustion chamber up (unshroud the valves, make same diameter as pistons/cylinder bore). Had 12.3/1 compression with stock 748 valves, 1mm squish

  3. #3
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    Cool

    Stig check out the guy over here with the Race Mongrel 748 851 in projects

  4. #4
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    toronto ontario
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    Default

    The only difference is the rocker covers are different to accommodate the shower injectors.
    I have a set, put them beside my 97sp heads can't tell the difference.

  5. #5
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    Hey Stig,

    Neil Spalding of Sigma Performance has written quite an informative write up about the 748RS vs 748R here: http://www.sigmaperformance.com/748r-748rs.html

    There's some great info on the heads in relation to the very prescriptive Supersport rules at the time. There is a statement in the rules:

    "01.58 DISCIPLINE SPECIFICATIONS - SUPERSPORT

    EVERYTHING THAT IS NOT AUTHORISED AND PRESCRIBED IN THIS RULE IS STRICTLY FORBIDDEN"

    And from what I can see the rockers are not mentioned so they must be OEM 748R.

  6. #6
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    Thanks guys.. ill have a pro getting them ready for action..

  7. #7
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    Default

    Memory stretch, but something was not as wide as a standard 748. I do know that they seem to chew rockers with the r cams. We put it down to really high valve acceleration during a "why is it so" session. Also cam nuts were loose on everyone that came in according to bob, I only ever worked on one. bob did have a collection of heads we use to drag out when contemplating all that port combustion chamber shape stuff. Actually pretty cool with 851, 916, 916sps, 748 standard/drop cam/RS, 998 and monster S4R. Just looking and seeing what our little Italian mates were thinking.
    Griff
    To infinity and.......

  8. #8
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    Quote Originally Posted by griff851 View Post
    Memory stretch, but something was not as wide as a standard 748. I do know that they seem to chew rockers with the r cams. We put it down to really high valve acceleration during a "why is it so" session. Also cam nuts were loose on everyone that came in according to bob, I only ever worked on one. bob did have a collection of heads we use to drag out when contemplating all that port combustion chamber shape stuff. Actually pretty cool with 851, 916, 916sps, 748 standard/drop cam/RS, 998 and monster S4R. Just looking and seeing what our little Italian mates were thinking.
    I have read that the 748RS ran some special belts (wider) .. not sure why .. ?

  9. #9
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    Back before I purchased my V2 604 cams (SPS equiv.) I looked into running other cams, ( 748 RS I believe) for either the intake or exhaust(don't remember whether it was an intake in place of the exhaust or visaversa) and found out that one had to narrow one of the cam lobes because it fouled the rocker arm. Supposedly in that application very close or the same as a SPS cam

    (Brad will know!)

  10. #10
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    Your right Brad will know. Pretty sure it was in the casting. Bit of bastard, I can picture the head and looking at ports and rocker pin mounting. I think Marvin is on the right track.
    Griff
    To infinity and.......

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