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  1. #1
    BoostCrzy's Avatar
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    Advent Timing curves...

    I recently put a fresh top-end on the ski(GP1200R) and threw the stock CDI back in the boat for break in(for fear of detonation)...after looking over the timing curves online I noticed that the stock curve is 10/10/9 degrees @ 7000rpm....and the advent YAM-94 is 21/18/16 degrees @ 7000rpm....thats a HUGE jump!..11/8/7 degrees increase over stock...Soooooo i was looking at the triple pipe curves and YAM-60 has 17.5/16/16 @ 7000rpm...a bit milder than the YAM-94...but still 7.5/6/7 degrees increase over stock @7000rpm...I would like to put the Advent back in but am curious as to what a safe level of timing would be for 93 octane pump gas and 140psi Riva cut stock head....maybe just use the YAM-60 curve?..since it has less timing overall??..any input would be appreciated!!

    -Jack


  2. #2

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    On pro-tec website, they list the stock 1200 curve at 13 degrees at 7000rpm, and I've heard that by 7250rpm the curve drops alot down to 9 on all 3 cylinders.

    I don't prop my ski to turn at 7000rpm.....I like 7200rpm+

    So running the Yam-60 curve will only add 4.5 degrees at 7000rpm. I think yamaha designed these to run on 87 octane.....so on 93 you could easily run more timing.

    Best thing to do, is just run it. Listen to see if its pinging. If too much timing it Will ping at around 5500. You can also pull the head after riding and inspect. Its usually not WOT that you will have problems, its around the 5500 rpm cruising speed.

  3. #3
    BoostCrzy's Avatar
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    Quote Originally Posted by Ronn25 View Post
    On pro-tec website, they list the stock 1200 curve at 13 degrees at 7000rpm, and I've heard that by 7250rpm the curve drops alot down to 9 on all 3 cylinders.

    I don't prop my ski to turn at 7000rpm.....I like 7200rpm+

    So running the Yam-60 curve will only add 4.5 degrees at 7000rpm. I think yamaha designed these to run on 87 octane.....so on 93 you could easily run more timing.

    Best thing to do, is just run it. Listen to see if its pinging. If too much timing it Will ping at around 5500. You can also pull the head after riding and inspect. Its usually not WOT that you will have problems, its around the 5500 rpm cruising speed.
    I was getting the info on the Advent site....hmmmmm....I wonder how close they truly are....either way I had a problem with detonation on the last top-end with the same exact parts using the YAM-84 curve...... disassembly after a 2-3hr 40mile ride, revealed pistons melting slightly by the exhaust valve...on one piston it got through to the top ring....this was using 93 octane(florida) and I believe was from sustained cruise at around 4500-5000rpm...
    cyl #1


    cyl #2

  4. #4

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    The stock curve has a spike around the 5000rpm range up to about 24.

    My advice- run it WOT all the time

    My pro-tec modded ignition moves the spike higher to 5500. So I'm either cruising at 4500rpm or at WOT to make it live.

  5. #5
    WATER WOODY's Avatar
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    Quote Originally Posted by BoostCrzy View Post
    I was getting the info on the Advent site....hmmmmm....I wonder how close they truly are....either way I had a problem with detonation on the last top-end with the same exact parts using the YAM-84 curve...... disassembly after a 2-3hr 40mile ride, revealed pistons melting slightly by the exhaust valve...on one piston it got through to the top ring....this was using 93 octane(florida) and I believe was from sustained cruise at around 4500-5000rpm...
    cyl #1


    cyl #2
    Yam84 has alot of timing in the mid range. Looks like that was your deto problem! 4-5k rpm is were the bad spot is, you should always stay out of that range. Pistons look lean.

  6. #6
    BoostCrzy's Avatar
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    Quote Originally Posted by WATER WOODY View Post
    Yam84 has alot of timing in the mid range. Looks like that was your deto problem! 4-5k rpm is were the bad spot is, you should always stay out of that range.Pistons look lean.

    EXACTLY!.....I emailed Advent to see about updating my T3 unit with some new curves with milder midrange timing...I plan to do some cruising on this ski with some friends soon who dont have 70+mph skis...so part throttle is kind of nice to stay with the group....

    ....I used the Curve Devil software to write a curve....maybe I can send that to them to have put in the box.......

    ...I also would like to see about having the external switching function...that way I can just switch from an aggressive curve to a mild quickly for cruising....hope to hear from them soon!!

    -Jack

  7. #7

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    Quote Originally Posted by BoostCrzy View Post
    EXACTLY!.....I emailed Advent to see about updating my T3 unit with some new curves with milder midrange timing...I plan to do some cruising on this ski with some friends soon who dont have 70+mph skis...so part throttle is kind of nice to stay with the group....

    ....I used the Curve Devil software to write a curve....maybe I can send that to them to have put in the box.......

    ...I also would like to see about having the external switching function...that way I can just switch from an aggressive curve to a mild quickly for cruising....hope to hear from them soon!!

    -Jack
    That would be nice to switch curves on the water. The only other option is to make it rich as hell for cruising.

  8. #8
    All hail the Chief! fullboogie's Avatar
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    We've been using/racing the Yam84 for 7 years with no problems, and it's a few degrees more agressive than the Yam94. You're not melting pistons because of the curve. You've got fuel problems judging by those pistons.

    I just ordered a new T3 from Greg. The new T3's have an external switch you can run to the outside of the CDI box that allows you to switch curves on the fly. Old units cannot be retrofitted. When (not if) your current unit dies, your new one will have this capability.

  9. #9
    BoostCrzy's Avatar
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    Quote Originally Posted by fullboogie View Post
    We've been using/racing the Yam84 for 7 years with no problems, and it's a few degrees more agressive than the Yam94. You're not melting pistons because of the curve. You've got fuel problems judging by those pistons.

    I just ordered a new T3 from Greg. The new T3's have an external switch you can run to the outside of the CDI box that allows you to switch curves on the fly. Old units cannot be retrofitted. When (not if) your current unit dies, your new one will have this capability.
    Well thats not very reassuring....I would HOPE this unit will last every bit as long as an OEM unit.....and how are the "new" T3's so different that they cant incorperate the switch on the older ones??...I have model 1290.

    ..and the YAM-84 curve was doing fine for me until I went on an extended cruise...the fuel system is working perfectly from what I can tell...Carbs are rejetted(125/110/1.5/95g)....ACC pump disabled...chokes removed...gives me no problems otherwise....runs great!....just getting deto in the cruise rpms...which makes sense to me looking at how aggressive the timing curves are in comparison with a stock curve...If most are able to run a 3 degree timing key with stock ignition curve and start to see detonation with anything over 4 degrees...how can the Advent be expected to keep the motor happy with an extra 7 degrees of timing at 4500rpm (which happens to be my cruise speed)and even +11degrees at 7000 rpm???...just seems like a huge jump!!


    -Jack

  10. #10
    XL1200Ltd-Keith's Avatar
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    The difference is a port on the back that the remote switch plugs into.
    Advent does not retrofit the older units.

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