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Yamaha sidewinder falls on face

Brett Allen

Brett Allen

Veteran
Joined
Oct 5, 2019
Messages
27
Age
35
Location
Sagle, Idaho
Country
USA
Snowmobile
2018 Yamaha Sidewinder MT-X SE 174, Ice Age Elevate, MCXPRESS stage 3, Earth X Battery, TKI Belt Drive, Stingray Mods Clutch kit. Apex primay, Nytro secondary.
I’ve got a 2018 sidewinder MTX, running precision 280 flash, hurricane performance secondary intercooler, external intake, race exhaust, rollover valve is dumped to tunnel exit, Tki belt drive, sting ray mods clutch kit with thunder products add ins. I’ve tried searching the mountain page but there isn’t much info or as many members, just looking to see if anyone here has experienced this.

sled falls on its face on longer hard pulls, never backfired or pops just like the ecu pulls power. Sled holds 8900-9000 rpm till it happens, doesn’t matter if it’s full of fuel or almost empty. Holds 19psi while in the throttle, all boost lines are tight and clean inside. I’ve sent the video to Precision and was told it wasn’t tuning related. I’ll add a link to the YouTube video of it. The file was too large to upload. It starts falling on its face 39seconds in and continues till I turn out.

 

19 PSI on 91 octane? I would guess your motor is detonating and pulling timing but you dont see flashing on the dash for the knock sensor?
 
MrSled said:
19 PSI on 91 octane? I would guess your motor is detonating and pulling timing but you dont see flashing on the dash for the knock sensor?
Click to expand...
Nope no lights no codes, running straight 100ll av gas
 
It's hard to tell from the video, but is that the sound of your BOV dumping on you?
 
fatchance said:
It's hard to tell from the video, but is that the sound of your BOV dumping on you?
Click to expand...

Fatchance, this sounds like the same thing you helped me out with at the beginning of the season. Belt (xs825) would slip and pull rpm's down.
You had me move weight from mid to tip of weight and heavier secondary wrap.
You can hear it happen at 7 seconds into the video also.
 
39 seconds at full throttle, high load high, and high angle of attack conditions is something we flat landers rarely experience.
IMO there are a few possibilities or combinations of :
-the blow off valve is suddenly dumping boost
-the knock protection warning system is not operating correctly
-the fuel supply is being over taxed because of the mods you have done, the length of the full fuel demand, and the angle the sled is running at.

When drag racing my SW on the 300hp setting last year my sled fell on its face in one of the heats. I immediately upgraded the fuel pump, regulator, rerouted the fuel return line to overhead of the fuel pickup slipper, and I also enlarged the fuel tank vent and I never had another issue.
 
sideshowBob said:
39 seconds at full throttle, high load high, and high angle of attack conditions is something we flat landers rarely experience.
IMO there are a few possibilities or combinations of :
-the blow off valve is suddenly dumping boost
-the knock protection warning system is not operating correctly
-the fuel supply is being over taxed because of the mods you have done, the length of the full fuel demand, and the angle the sled is running at.

When drag racing my SW on the 300hp setting last year my sled fell on its face in one of the heats. I immediately upgraded the fuel pump, regulator, rerouted the fuel return line to overhead of the fuel pickup slipper, and I also enlarged the fuel tank vent and I never had another issue.
Click to expand...
I ordered the TD high flow pump, I’m going to re route the return line when I install it, I’m running the turbo smart blow off valve, I’ll try that tomorrow, I have a hurricane flash device headed this way to flash the 270 elevation tune in it also to rule out that it isn’t just a precision tuning issue
 
sideshowBob said:
39 seconds at full throttle, high load high, and high angle of attack conditions is something we flat landers rarely experience.
IMO there are a few possibilities or combinations of :
-the blow off valve is suddenly dumping boost
-the knock protection warning system is not operating correctly
-the fuel supply is being over taxed because of the mods you have done, the length of the full fuel demand, and the angle the sled is running at.

When drag racing my SW on the 300hp setting last year my sled fell on its face in one of the heats. I immediately upgraded the fuel pump, regulator, rerouted the fuel return line to overhead of the fuel pickup slipper, and I also enlarged the fuel tank vent and I never had another issue.
Click to expand...
Can you explain the relocating of the return line please? First I've heard of needing to do this.
 
What does it hold for boost on a pressure test? Have you pressure tested the exhaust side yet?
 
DMCTurbo said:
Can you explain the relocating of the return line please? First I've heard of needing to do this.
Click to expand...

If you look at Precisions fuel pump upgrade install video you get a pretty good idea what needs to be done.
The Fuel Injection return line from the factory just dumps into the front of the fuel tank. The fuel pickup in the tank is in a slipper shaped reservoir that at certain angles and fuel levels can go dry...not good.
By rerouting the fuel return line to overhead of the fuel slipper you help ensure there is always fuel in the fuel pickup slipper the way it should be stock...IMO
 
Returning fuel back to the slipper a scare calling it here really helps. Hurricane sells grommets for this.
 
-the fuel supply is being over taxed because of the mods you have done, the length of the full fuel demand, and the angle the sled is running at.

When drag racing my SW on the 300hp setting last year my sled fell on its face in one of the heats. I immediately upgraded the fuel pump, regulator, rerouted the fuel return line to overhead of the fuel pickup slipper, and I also enlarged the fuel tank vent and I never had another issue.

X2
 
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