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Discussion Starter · #1 ·
Do the sled guys have to upgrade the rods for high boost? In other words how much power is this motor good for in stock form?
 

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Do the sled guys have to upgrade the rods for high boost? In other words how much power is this motor good for in stock form?
You don't need to, it is not Polaris....LOL
Seriously, up to 300 HP I was told this engine is good to go on internals , but for sure you will need to lower the compression by thicker head gasket, if going over 5-6 PSI boost ( 150 HP ) .IMO
milos
 

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You don't need to, it is not Polaris....LOL
Seriously, up to 300 HP I was told this engine is good to go on internals , but for sure you will need to lower the compression by thicker head gasket, if going over 5-6 PSI boost ( 150 HP ) .IMO
milos
Pretty much as milousa has stated. If you ride at elevation (5,000 up) you can get way with 10 lbs of boost on 91 pump gas before dished pistons or thicker head gasket. These motors that Yammi puts out nowadays is pretty solid and holds up to boost very well.
 

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I can't wait to put a turbo kit on mine.
Do you have one on order? What manufacturer are you looking at? I can't wait to see how the YXZ does with the hair dryer. I know the motor can handle the boost but it will be interesting to see how the SxS holds up. Yamaha usually overbuilds their toys but the kind of power this motor is able to produce on boost is staggering. Will be interesting to see what the week points end up being.
 

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Discussion Starter · #6 ·
Yes I have one on order white and blue. The only kit I have seen so far is the MPI kit. I really haven't researched the different kits yet.
 

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Milos, what advantage would a piston swap have over a head gasket if any, considering the Yamaha has forged Pistons already ?
 

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Milos, what advantage would a piston swap have over a head gasket if any, considering the Yamaha has forged Pistons already ?
Don't think you get any advantage to go with low compression piston on Yamaha where pistons are already forged. Main reason the people replace them on RZR's was to get forged piston in place of cast one Polaris engine use on NA engines. People I know who runs Yamaha Apex swap all use just thicker head gasket when run turbo. I know some say thicker head gasket could alter cams timing little bit, but I don't think make any big difference. Cometic even make thicker head gasket for Z1 Turbo engines, if you want to run bigger boost on pump gas, I run this gasket on my XP 900 swap. I think lower CR one point.
Honestly I will run just thicker head gasket and don't mess with pistons knowing they are forged already. IMO
milos
 

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Yes I have one on order white and blue. The only kit I have seen so far is the MPI kit. I really haven't researched the different kits yet.
MPI kit looks good, but not sold on the placement of inter cooler above the engine....lot of heat there.
For sled I can understand due the limited space, but for SxS really like to see inter cooler somewhere with more cold air going thru, but not sure if possible to relocated inter cooler with MPI kit, look like mount directly on TB's with some special plate.
milos
 

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Yea no need for rods on these motors. We use to run 17psi on pump on the Nytro's. This was with timing control and closed loop system.

Keep an eye out for Boost-It systems out of Canada. They are working on a turbo kit for the YXZ and they make some quality kits. Their fuel controller also works flawless, he already said it would be an air/water intercooler setup and is debating on GTX vs GT series turbos, but thinking GTX for spooling.

He makes a nice kit for the Viper, nytro, and also does turbo's for 2 stroke sleds.

I use to run an Impulse Turbo and Paul does beautiful work as well but he is into Ultra 4 racing now. He is making a kit for his yxz to race in KOH but is unsure if he wants to take the time to put it into production. I hope he does because he runs a full standalone system vs some piggy back systems.
 

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Here are the four different rods Yamaha uses in the various triple engines.

5JW-11650-01-00 $188 All Carbureted 973cc snowmobile engine, also FJR1300 motorcycle. Uses bolt w/ nut
8GL-11650-00-00 $160 All EFI 1049cc snowmobile engines up to 2015, possibly some 2016. Uses bolt w/ nut
8KH-11650-00-00 $118 Most EFI 1049cc 2016 and up snowmobile engines. Bolts that thread into rod
2HC-11650-00-00 $77 All YXZ 1000R 998cc 2016 and up. Bolts thread into rod

New - 8KJ rods are used in the new turbo snow engine. Heat treated, back to stud/nut.

8GL spec'd rods are .080 longer and .020 narrower at the bottom when compared to a 2HC, but both use the same bearings. That info is from Hurricane Performance.
 

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Here are the four different rods Yamaha uses in the various triple engines.

5JW-11650-01-00 $188 All Carbureted 973cc snowmobile engine, also FJR1300 motorcycle. Uses bolt w/ nut
8GL-11650-00-00 $160 All EFI 1049cc snowmobile engines up to 2015, possibly some 2016. Uses bolt w/ nut
8KH-11650-00-00 $118 Most EFI 1049cc 2016 and up snowmobile engines. Bolts that thread into rod
2HC-11650-00-00 $77 All YXZ 1000R 998cc 2016 and up. Bolts thread into rod
Look at the cost difference between all the other rods and the YXZ version. That suggests a lot. I hope the bean counters aren't taking over!
 
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I made a comment before that MPI claims the YXZ rods are different than the older Sled Rods. More testing is needed to verify what HP the stock YXZ can handle.
 

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The 8GL rods will hold quite a bit... it required 11 tons of pressure to get one to begin bending, the 8KH was a pretzel at 7 tons... what will the 2HC bend at? Check out TY4stroke for some info. Warning, -16 late build Viper turbo breakdowns, bad rods. | TY4stroke || Snowmobile Forum || Yamaha - 4 Stroke

If one doesn't have $1k to drop on rods, the 8GL will hold some good power. I suspect the 5JW will, too, but I did see a couple of 2005 973cc sleds throw the number 2 rod... I always suspected a spun bearing took them out, not terribly common. One sled I bought for parts threw a chunk of the number 2 rod through the front of the block, but it would still start, run, and move.
 
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