Engine damage question

[Mills]

So we went to Eagle Rive to take in the Derby and do some riding a week or so ago. While out riding my buddy with his 2012 Nytro was minding is own business going down a dirt road that also was part of the trail. "Crash" our buddy in the back of the pack decided he was going to grab a hand full of throttle on the straight section of dirt road and pass all of us. My buddy on the Nytro moved over to his left to get some snow in the track to lube the slides just as "Crash" was coming up on him. To avoid slamming directly into the back of the Nytro, "Crash" rode up on the snow bank on the left side of the road to hopefully miss the Nytro. That only shot him down the embankment into the left side of the Nytro. "Crash's" right front spindle when through the left side panel of the Nytro and made contact with the primary clutch. The Nytro was going about 40 mph at the time so the clutch was probably spinning somewhere around 6500 rpm I am guessing. The contact between the spindle and clutch resulted in the clutch being totally destroyed. Only the spring cover and fixed sheave are left along with a badly bend up primary spring. Everything else disintegrated into tiny pieces all over the trail.
So, here's my question - when we get the primary off the Nytro, what should we do to determine if the engine was damaged other than to check run-out of the stub shaft and listen for any not-so-good noises coming from the engine? The engine was off when they came to rest so I assume the impact caused it to quit. We have not attempted to restart it yet because I just found my clutch puller yesterday and didn't want to start it with the damaged primary still on it.

 

[steiner]

Oh boy! I hope Crash and Crashed are alright.
Other than checking for a bent crank I would look at the cam timing. An abrupt stop on the bottom end could cause the top end to skip. Compression test would be in order.

 

[Mills]

Crash did a superman over his handle bars and then bounced off he trail 2-3 ft high several times. The doc is telling him he torn the meniscus and MCL in his right knee. Also severely bruised several internal organs to the point that an MRI was in order. All is fine now but the state of the state of the Nytro remains a mystery until tomorrow night. How easily can the timing chain jump teeth? What should we unplug to keep the engine from firing when we do the compression test?

 

[steiner]

Oh wow. That was quite the landing Crash had. Sounds like he is lucky to still be breathing.
As far as the compression test goes the motor won't fire up as the plugs will be out. No spark no boom.

 

[Mills]

No spark no boom but the coils will be getting juice. Do I simply put the plugs in the caps and let the spark discharge on a metal surface like I would with a 2-stroke?

 

[mx3_ryder]

No need to put the spark plugs back in the coils when doing your compression test

 

[Mills]

Are Nytro engines "interference fit" engines meaning if the valve timing is off the pistons can make contact with them? Also, what is the compression range for this engine? I was thinking it is 120-124 psi but I cannot remember if that is right or not.

 

[steiner]

I think in almost engine the valves will hit the pistons if the timing has jumped.
Unplug the coil packs from the wiring harness. There will be no sparking or arcing.

 

[NOS-PRO]

The Nytro 3 banger is a good engine.

I would turn over the engine with a wrench on the end of the bolt to see if you have interference or issues.

Remove the clutch pieces and pull the coil wires like said mentioned above. After cranking a couple times, plug in and fire up the engine.

I am betting the engine will be fine.

 

[Mills]

So here's the report on the damage. Turned the engine over by hand to make sure nothing was binding or making noise. All turned out good. Next, we took the plugs out and rolled the engine over with the starter and again no issues. We checked the run-out of the stub shaft just rolling the engine over with the starter - big problem. We had about 0.078" run-out. We decided to put the plugs back in and fire the engine and found that it ran well but we could hear a bearing issue with the stub shaft. So, we removed the stub shaft and found that the impact had damaged the bearing in the stub shaft assembly. We took the assembly apart and checked the run-out of just the stub shaft itself and found that it was not bent. All of the run-out was due to the damaged bearing. I now have a new stub shaft bearing and oil seal on order and should be able to get the sled back up and running midweek next week.

 

[NOS-PRO]

So here's the report on the damage. Turned the engine over by hand to make sure nothing was binding or making noise. All turned out good. Next, we took the plugs out and rolled the engine over with the starter and again no issues. We checked the run-out of the stub shaft just rolling the engine over with the starter - big problem. We had about 0.078" run-out. We decided to put the plugs back in and fire the engine and found that it ran well but we could hear a bearing issue with the stub shaft. So, we removed the stub shaft and found that the impact had damaged the bearing in the stub shaft assembly. We took the assembly apart and checked the run-out of just the stub shaft itself and found that it was not bent. All of the run-out was due to the damaged bearing. I now have a new stub shaft bearing and oil seal on order and should be able to get the sled back up and running midweek next week.

Well done