RS Nytro - Genesis 120 - Blown Up Engine Tear-down Pictures

[tcb4]

Here's a photo album of my nytro's engine after it threw a rod through the side of the motor. Not 100% sure on the cause; it doesn't look like the piston hit the valves and the bearing and wrist pin were loose. Piston also moved freely. Maybe just a fatigue failure? Valves looked good from what I could see, but it's proving difficult to remove the head.

Link to album:

https://imgur.com/a/l8DvA

Edit: Valve struck the piston which appears to have caused the connecting rod failure. Not sure what got wedged in the valve. Air filters (metal + foam) were on, so it must have already been in there or something. Air filter hasn't been opened since the start of last and it was fine all last season. Unfortunate to say the least.

 

[Vector LTX GT 08]

Here's a photo album of my nytro's engine after it threw a rod through the side of the motor. Not 100% sure on the cause; it doesn't look like the piston hit the valves and the bearing and wrist pin were loose. Piston also moved freely. Maybe just a fatigue failure? Valves looked good from what I could see, but it's proving difficult to remove the head.

Link to album:

https://imgur.com/a/l8DvA

Edit: Valve struck the piston which appears to have caused the connecting rod failure. Not sure what got wedged in the valve. Air filters (metal + foam) were on, so it must have already been in there or something. Air filter hasn't been opened since the start of last and it was fine all last season. Unfortunate to say the least.

That is Crazy!! That stinks that happened to you. At least it seems like you know how to tear it down, and rebuild it!! Are you going to be buying the new parts, and rebuilding it your self? Or have some one else do it? Or just drop in a good used motor?

 

[tcb4]

That is Crazy!! That stinks that happened to you. At least it seems like you know how to tear it down, and rebuild it!! Are you going to be buying the new parts, and rebuilding it your self? Or have some one else do it? Or just drop in a good used motor?

Yeah, just really unlucky as far as I can tell. Thankfully my dad has a nice heated pole barn with loads of tools and quite a bit of experience working on sleds for the last 35+ years. Probably going to plan on putting a used motor in it if I can find one, possibly from a wrecked sled. They're pretty hard to find though, the newer nytros were much more popular. If I don't find anything I'll probably be forced to part it out or consider other options. I have a spare sled I can ride this year if a motor doesn't turn up soon. I can't imagine rebuilding this one with the amount of damage the broken connecting rod did. I'm not really sure how long everything went without oil because it took out all the lines to the filter below. Crank and head look good, but just not worth risking it blowing up again with how cheap these sleds are wrecked.

 

[Vector LTX GT 08]

Yeah, just really unlucky as far as I can tell. Thankfully my dad has a nice heated pole barn with loads of tools and quite a bit of experience working on sleds for the last 35+ years. Probably going to plan on putting a used motor in it if I can find one, possibly from a wrecked sled. They're pretty hard to find though, the newer nytros were much more popular. If I don't find anything I'll probably be forced to part it out or consider other options. I have a spare sled I can ride this year if a motor doesn't turn up soon. I can't imagine rebuilding this one with the amount of damage the broken connecting rod did. I'm not really sure how long everything went without oil because it took out all the lines to the filter below. Crank and head look good, but just not worth risking it blowing up again with how cheap these sleds are wrecked.

Yup true. A 120hp carbed vector motor would work on your Rs Nytro. Yeah, you would need to buy a new block, wonder how costly that part would be? Either way that stinks on what happened to you. Post up pictures if you decide to rebuild it, I would like to see the step by step process.

 

[tcb4]

Yup true. A 120hp carbed vector motor would work on your Rs Nytro. Yeah, you would need to buy a new block, wonder how costly that part would be? Either way that stinks on what happened to you. Post up pictures if you decide to rebuild it, I would like to see the step by step process.

Thanks! Yeah, looking for RS Rage, RS Vector and RS Nytro motors. Will do, hopefully I get it back together. It's actually in really good shape, so I'd hate to see it just parted out.

 

[tcb4]

Must be doing something wrong as my Dad's 2005 RS Rage (same 973cc carbureted 3 cylinder) just did the same thing, though several years later. Machine has about 8k miles on it and is even rocking the transplanted hood from the ill fated RS Nytro as his hood was in rougher shape. Not sure what caused it this time, nothing in the airbox and machine has been taken care of. Not at WOT this time, just cruising down the road after about 5 miles of riding. Wondering if a keeper or something is failing and allowing the valve to drop into the cylinder, though I am not certain that fully explains why it is always the center cylinder. He may try to find another motor, but I figured I would post this here as it seems very peculiar to have two similar model year units fail in the same way. Bad luck it seems. Never did rebuild the Nytro, but my Dad has more time on his hands and is more mechanically inclined/equipped. I think the toughest part will be sourcing a motor for a reasonable price...

Updated the below gallery with a couple pictures to highlight the damage on the 2005 rage. See the last two pictures... Smaller exit hole this time.

https://imgur.com/a/l8DvA

 

[Stubbs]

Was the cam chain tensioner updated to the newest version on either of these 973’s?

 

[tcb4]

Was the cam chain tensioner updated to the newest version on either of these 973’s?

No, I do not believe so or at least not verified (both sleds were purchased used). Is this a common failure method if it jumps timing? in both instances they were still running/driving (for 1-2 minutes) on two cylinders after the center rod ejected. Both were shut down after seeing the oil. Timing was not so far off then that it could not run, no obvious evidence of valve contact on cylinders 1 or 3. So, if jumped timing was to blame, wouldn't cylinders 1 and 3 also have had pistons contact the valves and fail catastrophically? I do not recall any stripped teeth/chain damage from the first teardown, either.

If this method of failure matches, then I guess that could be very likely, though. It seems this span of motors had a definite issue with the tensioner and it is very possible neither were updated. Thanks for the reply/insight.

 

[Stubbs]

I’ve been involved with a couple 973 cam tensioner upgrades, but have never seen one fail first hand. The triple three holers have been bulletproof aside from the early versions with the older version tensioner, and even those were few and far between when these sleds were new ish. I’d need to research some failures, but I’d be willing to bet both of your motors went down due to cam timing being out of whack due to a failed tensioner, that’s the only thing that makes any sense.

 

[Fast Lane]

I don’t see where the valves would have impacted the top of the piston in your pictures. I don’t think it jumped time.

 

[tcb4]

I don’t see where the valves would have impacted the top of the piston in your pictures. I don’t think it jumped time.

Those pictures are from when the center rod went on my 2006 Nytro. In the picture of the "top of the piston" you can see the slightest indentation in one of the valve relief cut outs, but it does not look very significant... BUT the valve associated was also slightly bent. Theory could be that a single valve stuck open for some reason or the con rod failed first and the piston bounced around while it was still running. As you said, there is not much in the way damage to the top of the piston.

I may update this again if my Dad does decide to tear it all apart (again for the rage). He is retired and may try to fix it for "fun." I guess I would see then if this was the same failure method or if it is more clear that valves struck the piston on the 2005 Rage. Does not seem worth it to try to find another motor as they are 1500$ and the whole sled could be replaced for not too much more.

 

[Fast Lane]

That’s my worse nightmare lol. I love my sled but it would be a tough call gambling on a used engine.

Maybe a defective connecting rod? Or bad batch. Hard to say.

I’ve taken apart two car engines that jumped significant timing. It was very obvious impact marks on the piston and the timing components were trashed.

I’ve heard of quite a few 973 with wild mileage on them with no issues. No one seems to know anything about cam tensioner update. I assume they were running the original tensioner. I’ve never bothered to look on my sled. Maybe I should…….

 

[Stubbs]

2008 + 973 carbed triples had the updated tensioner from the factory, everything before that either has the old style or has been updated. I’ve been involved with a couple sleds for the update. Although failures of the tensioner are rare, if it lets go it takes the motor with it, period.