Author Topic: broken cylinder  (Read 693 times)

Racingwest

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broken cylinder
« on: September 30, 2019, 04:06:08 AM »
Hi all,

2015 sherco  300 sef r factory

Unknown hours but had a new piston kit fitted 3 hours ago.

Ran fine for 3 hours then at slow speed a load noise like a chain snapping and cut out.

Stripped it down and found the bottom of the cylinder had broken off!

Just trying to make sure that after the rebuild it does not happen again.

Oil and coolant levels fine bit oil does look very old and black.

Thank for you help.

Clay

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Re: broken cylinder
« Reply #1 on: September 30, 2019, 08:48:38 AM »
Never ever seen that before. Not sure what your question is ?
Clay Stuckey
Sherco Offroad  www.shercooffroad.com
email: clay@shercooffroad.com
cell: 615 347 6519
Tennessee, USA

Racingwest

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Re: broken cylinder
« Reply #2 on: September 30, 2019, 09:30:08 AM »
Obviously I need a new one and lots of other parts.
Just wondering what could have caused it to fail like this.
I donít want to rebuild it for it to happen again,just trying to figure out what happened so it doesnít happen again.
Hoping someone has some answers 🤞

VxZeroKnots

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Re: broken cylinder
« Reply #3 on: September 30, 2019, 05:13:28 PM »
It looks like there is a ton of black silicone around the base of the jug which leads me to believe it was leaking? I'm guessing there was a issue with the base gasket or cylinder bolt torque that caused this. The nikasil on the bore also looks like hell but that could have happened after it let go. 

jamracing

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Re: broken cylinder
« Reply #4 on: October 01, 2019, 07:18:40 AM »
How many hours were on the piston? what size came out, what size went in?
How many on the cylinder?
Did you measure the cylinder for oval-ness?
I'm guessing the cylinder was worn, which probably contributed to piston rock. Sucks either way...
New to the blue
2017 300 SE-R

rkm

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Re: broken cylinder
« Reply #5 on: October 01, 2019, 07:40:55 AM »
I would also take a close look at the crank.

Racingwest

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Re: broken cylinder
« Reply #6 on: October 01, 2019, 11:47:25 AM »
Thanks piston less than 30 hours, engine unknown hours. B piston was fitted.
Going to check the crank out tomorrow when a FYI and some v- blocks.
I hope they are ok or itís going to be a massive bill☹️
Thanks for your inputs

Dangermouse

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Re: broken cylinder
« Reply #7 on: October 03, 2019, 04:09:08 AM »
Possible that the piston seized in the bore on the down stroke, breaking off the lower bore area.
As to why....???
Not enough oil, not enough clearance, lost oil pump drive, lost coolant???
2019 300 SEF Factory
2011 TE449
Admin - Sherco Riders & Owners FB group
Just an old quick trail rider having a go.
From Qld Australia 🌏

Racingwest

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Re: broken cylinder
« Reply #8 on: January 07, 2020, 12:39:01 PM »
Hi just thought I would report what I found after a complete rebuild.

The reason it failed was the previous owner had but a helicoil in the rear r/h crankcase bolt  hole, flush with the top of the cases.

This blocked the oil way to the piston skirt oil jet , causing the damage.

New crankcase and Con rod piston valves etc and is now running sweet.

Thanks for your input