Higher Compression and Advanced Timing 94 750 SSXI Reliabilty
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  1. #1
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    Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    I have a 94 750 SSXI I've started putting some mods and upgrades into and am just looking for some insight and assurance that what I'm doing and have done will keep the motor running safely without any major concerns.

    Current Upgrades:
    I have just sent my head off to Chris Newmiller to be worked.
    Coffman Exhaust (manifold to waterbox)
    R&D Timing Advance Plate (*not installed yet*)
    R&D Ride Plate
    R&D Intake Grate
    Solas 14/19 Impeller

    My main question is, will the higher compression along with the advanced timing remain safe for my motor WOT for extended periods? Also will 92 octane fuel be fine with the combination of the higher compression and timing advance? I cannot find any info regarding the timing curve for my motor. From reading, http://www.rd-performance.com/produc...etrorocket.asp, it seems the R&D timing plate advances the timing a full 7 degrees in the low-mid RPM range. I'm curious as to how this will affect the motor at higher RPMs, if at all.

    Thanks

  2. #2
    PWCToday.com Is My Home Away From Home jetman624's Avatar
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Ask Newmiller how he feels about a fixed advance plate giving you that much timing advance at WOT.

    I agree with him. I don't think it is safe and done run it on my boats.
    '02 SXi Pro: Factory Limited pipe, ported SXR cyl, SSP stearing system, WORX ride plate, skat trak intake grate, blowsion tubbie II, 3DR SS hull extensions, 3DR trued hull, 3DR pump shoe mod, bored pump nozzle

    '92 X2: Mostly stock, except for the 750

    '91 X2: #718

  3. #3
    Top Dog TMali's Avatar
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Im running a 94 ssxi motor in my x2.

    This is my opinion, but others will tell you else wise. I dont like the timing plate, i dont like the idea of always running at 7 degrees advance. You put that with extra compression and there is a chance you will melt the engine down at WOT runs.

    On my motor i have the MSD CDI box. It will advance the timing curve as needed through out the RPM range. The MSD cdi's are quite abit more expensive compared to the $25 advancing kits.

    New miller im sure will give you some great advice if you ask him, since you are having him do some work for you.

  4. #4
    PWCToday.com Is My Home Away From Home mcn6's Avatar
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Advance plates increase ignition timing 7 deg through the entire timing curve and I do not recommend them with pump gas.
    Last edited by mcn6; 03-23-2015 at 01:33 PM.



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  5. #5
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Quote Originally Posted by mcn6 View Post
    Advance plates increase ignition timing 7 deg through the entire timing curve and I do not recommend them with pump gas.
    From reading R&D's build here, http://www.rd-performance.com/produc...etrorocket.asp, which included the timing plate they say it's completely safe with 92 octane and this build was for 92 octane.

    While the final touches were being done to the induction system, Glenn was installing an R&D timing advance plate. This trick little item advances the 750's timing from 16 degrees to a full 23 degrees. This part really helps improve low/mid-range performance. Next came the new R&D cylinder head, its specially designed combustion chamber raises the compression, about 25 pounds over stock. Perfectly suited for 92 octane pump gas.
    I know it's safe for recreational riding, my concern is with extended WOT riding, and if it is still alright.
    Last edited by Nickefer; 03-23-2015 at 01:48 PM.

  6. #6
    PWCToday.com Is My Home Away From Home jetman624's Avatar
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Quote Originally Posted by Nickefer View Post
    From reading R&D's build here, http://www.rd-performance.com/produc...etrorocket.asp, which included the timing plate they say it's completely safe with 92 octane and this build was for 92 octane.
    What compression are they running on the build in that article?
    '02 SXi Pro: Factory Limited pipe, ported SXR cyl, SSP stearing system, WORX ride plate, skat trak intake grate, blowsion tubbie II, 3DR SS hull extensions, 3DR trued hull, 3DR pump shoe mod, bored pump nozzle

    '92 X2: Mostly stock, except for the 750

    '91 X2: #718

  7. #7
    PWCToday Newbie
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Quote Originally Posted by jetman624 View Post
    What compression are they running on the build in that article?
    They never state specifically, but it does say it raises 25psi over stock which would put it around 175psi.

  8. #8
    PWCToday Guru 37's Avatar
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Quote Originally Posted by Nickefer View Post
    they say it's completely safe with 92 octane
    There's no such thing as "completely safe." Overall boat weight, pump load, fuel quality (and mistakes do happen by the gas stations), engine temp, water temp, air temp, humidity, relative air density, compression, timing, and so on all play a role into this. Articles are meant to sell parts. R&D won't buy you a new top end if you burn yours down since they can easily claim any number of factors that don't blame their static advance plate, even if it was the root cause.

    Besides agreeing with the others that static advances are a BAD idea, I've seen plates come off and destroy the pickup, flywheel, and bendix all in one shot. I've never run one on my builds and never will. No one can convince me otherwise, including the "but I've run one and never had a problem" crowd.

    If reliability is your main concern, avoid this part.

  9. #9
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Quote Originally Posted by 37 View Post
    There's no such thing as "completely safe." Overall boat weight, pump load, fuel quality (and mistakes do happen by the gas stations), engine temp, water temp, air temp, humidity, relative air density, compression, timing, and so on all play a role into this. Articles are meant to sell parts. R&D won't buy you a new top end if you burn yours down since they can easily claim any number of factors that don't blame their static advance plate, even if it was the root cause.

    Besides agreeing with the others that static advances are a BAD idea, I've seen plates come off and destroy the pickup, flywheel, and bendix all in one shot. I've never run one on my builds and never will. No one can convince me otherwise, including the "but I've run one and never had a problem" crowd.

    If reliability is your main concern, avoid this part.
    I appreciate your response. I was intrigued by it from reading how it helps with throttle response on the low end which can always be more fun.

    I am just not as knowledgeable at all of this with skis as all of you are, but I am aware of the how these changes can affect the motors.

    Thanks

  10. #10
    PWCToday.com Is My Home Away From Home jetman624's Avatar
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    Re: Higher Compression and Advanced Timing 94 750 SSXI Reliabilty

    Quote Originally Posted by Nickefer View Post
    They never state specifically, but it does say it raises 25psi over stock which would put it around 175psi.
    If Newmiller is cutting your head to run 92 octane gas, and you understand how advancing your ignition-- especially THAT much on the top end-- creates ADDITIONAL heat in the combustion chamber, the answer is an obvious "no, don't run it".

    If Newmiller is cutting your head to run 92 octane, and you want to run a HIGHER octane than that, than maybe you could get away with the fixed advance. But running compression that necessitates 92 octane and then adding a fixed advance on top of that is probably not wise.
    '02 SXi Pro: Factory Limited pipe, ported SXR cyl, SSP stearing system, WORX ride plate, skat trak intake grate, blowsion tubbie II, 3DR SS hull extensions, 3DR trued hull, 3DR pump shoe mod, bored pump nozzle

    '92 X2: Mostly stock, except for the 750

    '91 X2: #718

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