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998 engine rebuild

Discussion in 'SideWinder Trail Talk' started by Turboflash, Apr 16, 2021.


  1. Turboflash

    Turboflash TY 4 Stroke Master

    Messages:
    1,345
    Location:
    Rochester, MN
    Country:
    USA
    Snowmobile:
    '17 ZR9000 Ltd. PEFI Stg 4.
    This post is just FYI for those who may be interested. Just trying to do my part to keep TY alive during off season :D.
    As some you may remember, I posted back in March that my engine had deto damage at the end of this riding season. A little background ...
    Sled is '17 ZR9000 Ltd with about 5600 miles (225 hours). Tuned since day 1 w Stage 3 PEFI. Meticulously prepped and maintained. Stock air box. 2.5" straight-thru D&D stainless performance muffler. Stock fuel system. BOV. Silicon boost tubes. Intake boot spacers shortened; no boost leaks up to 25 psi. Rollover deleted from day 1.
    Gas mostly 92 octane w ethanol and this past winter 93 octane non-ethanol. Occasionally 91 octane (on trail). ARP head studs from day 1.
    Trail/lake riding mostly northern Wisconsin. Occasional multi-mile WOT. Coolant temps normal.

    At end of season I could tell when cranking engine was hurt. Compression test showed center cylinder about 25 psi lower than other 2. Fiber-optic camera inspection showed center piston with serious deto and other 2 pistons with some deto but piston over-heating evident. Piston valve relief areas showed they got so hot the aluminum had sagged inward causing top ring groove to open as the relief area tipped toward center of pistons. Also, because that area had tipped inward, the outer edge of piston was then in contact with cylinder wall.

    My rebuild is now complete. All engine bearings looked like new. No wear, no dirt, etc. Cylinder walls like new. No wear. No damage from detoed pistons. Top ring on center piston was ductile and had lost allot of it's temper due to excessive heat.
    To hopefully address piston over-heating, I sent pistons to Swaintech to get domes ceramic coated. I also used a drum sander on die grinder to carefully smooth and blend the sharp thin edges near valve relief areas. IMO, these thin sharp edges do not belong in a turbo charged engine as it is a natural place for excessive heat and deto to start. Used all stock Yamaha parts. Upgraded fuel system using kit from PEFI (larger pump, return line goes into basket). New and better tank strainer. Added a 10 micron high-flow post filter right before fuel rail to keep any debris out of injectors. Sent fuel injectors out for clean and flow. 2 of 3 were down 3.5% due to debris in inlet filters! Also going to try octane booster this next riding season although there is some debate as to whether they really work. Will avoid long (over 1 mile) WOT. IMO, cooling system on these sleds is designed for 200 HP not 280. Adequate for 200 HP at high duty cycle but not enough for 280HP for long pulls. Even without deto, pistons overheated (aluminum began to sag) just plain from being too hot. Coolant temps we see on cluster is temp of coolant coming into head from heat exchangers, not outgoing to exchangers. IMO, head gets so hot on long WOT pulls, coolant temps may be over 220-230! Pistons are cooled from below by oilers that spray into bottom of piston. At WOT for long pulls (1-2 miles with 280HP tune), this is not enough to keep piston cool.

    Pics attached. Note piston 2 has 2nd ring stuck. That's the way it came out. If you look at valve relief areas, you can see the sagging I mention. Engine had 5,600 miles tuned since day 1. Engine fresh and ready.
     

    Attached Files:

    Sorcerer, kinger, yamamarc and 9 others like this.
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  3. STAIN

    STAIN Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    3,015
    Location:
    Vermont
    Country:
    USA
    LOCATION:
    Vermont
    Nice. Are you going to run the same tune?
     
  4. DMCTurbo

    DMCTurbo VIP Member VIP Member

    Messages:
    2,176
    Location:
    Ontario
    Country:
    Canada
    Snowmobile:
    2017 Sidewinder XTX LE 137
    LOCATION:
    Greater Sudbury
    1 to 2 mile WOT pulls lol!! I thought us Canucks were haywire!!
     
    Brotherdan likes this.
  5. jonlafon1

    jonlafon1 Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    2,359
    Location:
    Mount Morris, WI. Chaney Lake, Upper MI eh!
    Country:
    USA
    Snowmobile:
    2022 Sidewinder LTX_SE

    2021 Arctic Cat 8000

    2017 Sidewinder LTX-SE. 11750 miles (SOLD)
    :rofl:
     
  6. justinator

    justinator Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    969
    Location:
    Maine
    Country:
    USA
    Snowmobile:
    2020 sidewinder xtx se
    Most boosters with mmt work to reduce knock. I used some boostane professional this winter and I chose it because its the only one I could find that contained mmt and did not seperate. Typically fuel mixed with a booster using mmt loses its effectiveness if not used fairly quick because of the seperation. Boostane claims their suspension formula prevents this from happening. I dont know if it does as I have no way to test this but the stuff works. Ive added small amounts trail side (2-2.5oz) to full tank of fuel and saw its effectiveness via datalog.
    With that being said I hope after all that work you consider a tuner utilizing the gap software with a functioning and correctly operating knock protection system. It would work with your header, muffler and fuel system with only hardware change possibly having to swap the map sensor to one made by GAP.
     
    yamamarc and DMCTurbo like this.
  7. STAIN

    STAIN Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    3,015
    Location:
    Vermont
    Country:
    USA
    LOCATION:
    Vermont
    Sorry, I worded that wrong.
    Which tune are you going to run?
    Didn't mean to sound like I was trying to be a dink, these problems with certain tunes suck for those involved.
     
  8. jonlafon1

    jonlafon1 Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    2,359
    Location:
    Mount Morris, WI. Chaney Lake, Upper MI eh!
    Country:
    USA
    Snowmobile:
    2022 Sidewinder LTX_SE

    2021 Arctic Cat 8000

    2017 Sidewinder LTX-SE. 11750 miles (SOLD)
    All good I think.. Not trying to Speak for Flash.. I was thinking the EXACT same question you asked..
     
  9. Tcat100

    Tcat100 VIP Member VIP Member

    Messages:
    130
    Location:
    Chicago
    Country:
    USA
    Snowmobile:
    ZR9000
    Trail 8 Michigan UP...many stretches 5 miles plus. Piston or kevlar alley, you pick!
     
    SledFreak and jonlafon1 like this.
  10. jonlafon1

    jonlafon1 Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    2,359
    Location:
    Mount Morris, WI. Chaney Lake, Upper MI eh!
    Country:
    USA
    Snowmobile:
    2022 Sidewinder LTX_SE

    2021 Arctic Cat 8000

    2017 Sidewinder LTX-SE. 11750 miles (SOLD)
    I know that one!! Run it and immediately pull panel and check your clutches with your hands! If you can hold your clutches on this trail your clutched good!
     
    SledFreak and actionjack like this.
  11. TrueBlue

    TrueBlue Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    575
    Location:
    Franklin Park, IL
    Winter home right off trail 8 in Wakefield area
     
  12. sideshowBob

    sideshowBob Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    1,133
    Location:
    North West Ontario
    Talking about long wide open/high speed running...The old Griffith Mine rail bed heading North of Aimsdale to Ear Falls Ontario...approx 20 miles of straight groomed trail....separates the men from the Boys or should I say 2 strokes from 4 strokes!
     
    Last edited: Apr 18, 2021
  13. RAMSOMAIR

    RAMSOMAIR TY 4 Stroke Master

    Messages:
    1,090
    Location:
    Ontario, Canada
    Rattle rattle rattle BOOM!
     
  14. 72Gran

    72Gran Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    101
    Location:
    Ontario
    Country:
    Canada
    Snowmobile:
    15 Apex XTX
    21 Sidewinder LTX GT
    Ran my 98 SRX 20 miles wide open on Lake Nipissing along with many other long mile pulls. Yamaha has forgotten more than the current two stroke builders know.
     
    Stubby Hungwell likes this.
  15. SledFreak

    SledFreak TY 4 Stroke God

    Messages:
    5,231
    Location:
    Ontario. Canada
    Country:
    Canada
    Snowmobile:
    Current 2020 ThunderCat, 2017 ZR 6000 Roger Skime, gone is the 2016 ZR 4000 RR, 2012 MXZ 1200 Renegade, 2010 MXZ 1200, 2009 Nytro XTX, 2006 Apex GT, 2003 MXZx 800 REV, etc..
    Ran that trail every year until fu*&%in covid hit!!! I can't get over the border because of our dick PM!
     
    sailor joe and Stubby Hungwell like this.
  16. jonlafon1

    jonlafon1 Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    2,359
    Location:
    Mount Morris, WI. Chaney Lake, Upper MI eh!
    Country:
    USA
    Snowmobile:
    2022 Sidewinder LTX_SE

    2021 Arctic Cat 8000

    2017 Sidewinder LTX-SE. 11750 miles (SOLD)
    Guessing your place and mine are about 12 miles apart! Chaney Lake just south of you off trail 11s
     

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