SXR Blown motor!!!

[sxrchris]

Ok can anyone help me figure out how something like this happens!!!! Went surf riding yesterday, was out for about 25 min then bam! It felt like I sucked something up like seaweed, complete loss of power. I shut down felt around the pump, nothing. I tried to restart but no luck, it felt like it turned over a little then all i could get was a click. Got it home and this is what i found...... :/ Front piston cracked, big a** notch in exhaust mani, rod sticking through case. I am still in shock!!! I recently put a tdr waterbox in and did the temp bypass jump, been running 93 50:1

 

[550/440]

How long since it was rebuilt? How many hours on the engine? Piston collapse or upper rod bearing sieze is most likely what happened. I've seen a few motors cut themselves damn near in half. Sorry for your predicament!

 

[sxrchris]

Rebuilt in 07, lots of hours. Pretty much ride all year long down here in florida!!

 

[550/440]

Suggested maintenance: Wrist pin bearings, I replace them every season / 40 hrs. They are a weak link. While the top end is off, measure the bore and piston and check for wear (bore gauge, not just calipers).

 

[Matt_E]

Rebuilt in 07, lots of hours. Pretty much ride all year long down here in florida!!

Six years of all season riding is asking a little much of that motor.

 

[sxrchris]

That's true Matt! After pulling motor i tried to spin drivline, no go it was jammed tight. Finally inching back and forth it now spins freely. I think the water in the crankcase was from the rod breaking through cooling port. Could some thick a** seaweed at slow speeds do this??

 

[snowmann399]

I'm new to watersports but have a good mechanical background.. I would check for a bearing failure since the rod broke. Try to spin whats left of the rod to see if the bearings are ceased. No load reving (seaweed and no water to the prop) is never good on any engine.. but I personally don't think it was the major factor in your failure.. Hope this helps I'm a noob here..

 

[rollin5150]

Also take note that your pistons have been washed clean. You ski was either running super rich or you had a water leak. If it was a water leak, this could also contribute to a bearing failure. As Matt stated, that is a lot of run time on an engine.

 

[jetpilot808]

Did you ever figure it out? My question is, how do you prevent it?

 

[Matt_E]

Did you ever figure it out? My question is, how do you prevent it?

Preventive rebuild is how you prevent that. Everything in that motor is a wear part. After a few seasons, it's just time to rebuild.

 

[sxrchris]

Jetpilot 808 I'm not 100 percent but i think it was mainly the seaweed completely locking up prop against housing. Like i said earlier after i pulled the motor the driveline was locked tight wouldn't budge util trying to rotate back and forth for a few minutes then popped free. I could even see light on one side of prop and it wedged on the other side!!
One thing that's a little questionable it the crank. I'm new to all this but bearing #1 doesn't rotate,(don't know if it's supposed to) and bearing 2 flywheel side isn't as smooth as the rest. But that could have happened from the water sitting in the crankcase overnight. Everything else to me looked pretty good.

 

[sxrchris]

Preventive rebuild is how you prevent that. Everything in that motor is a wear part. After a few seasons, it's just time to rebuild.

I'll be doing this from here on out though just to be safe!!

 

[djkorn1]

Preventive rebuild is how you prevent that. Everything in that motor is a wear part. After a few seasons, it's just time to rebuild.

Yep. Every 3 for me.

 

[Matt_E]

Jetpilot 808 I'm not 100 percent but i think it was mainly the seaweed completely locking up prop against housing. Like i said earlier after i pulled the motor the driveline was locked tight wouldn't budge util trying to rotate back and forth for a few minutes then popped free. I could even see light on one side of prop and it wedged on the other side!!
One thing that's a little questionable it the crank. I'm new to all this but bearing #1 doesn't rotate,(don't know if it's supposed to) and bearing 2 flywheel side isn't as smooth as the rest. But that could have happened from the water sitting in the crankcase overnight. Everything else to me looked pretty good.
View attachment 221186

This had nothing to do with seaweed. Your crank went too long without a rebuild and that's all.

 

[jetpilot808]

Could compression test tell you if you need to rebuild? But that would tell you just the top end, right? How could you tell if you need to rebuild the crank?

 

[Matt_E]

You can check rod play and bearing noise or smoothness. Other than that, it is a really good idea to track hours and rebuild the crank after x number of hours

 

[Scorn800]

That was a pretty good grenade. Sometimes it just bad luck.
I know of stock sxr's with hundreds of hrs on them that are still running. If you take care of them, use good oil and gas, and don't flood motor often a stock motor can last a long time.

 

[crossr]

This had nothing to do with seaweed. Your crank went too long without a rebuild and that's all.

What he said... Tracking hours is probably ideal but not really practical(for me anyway) I think it is best to just get a new crank every 2 to 3 years. 6 years? you were living on borrowed time.

 

[jetpilot808]

Who is good builder for Kawis?

 

[socal750]

Looks like classic kawi terminal piston skirt failure to me...once those motors drop 10-15 psi you know it's getting close it trashed everything