What to do?? Broke piston.

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Freshen both sides? Or?

Rebuild top end on both sides
Just replace what’s broken
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What to do?? Broke piston.

Post by AV8OR » Mon Jul 08, 2019 4:47 pm

OK so my 2008 patrol broke the left side piston. It has just over 11,000 km on it. What I am wondering is what the majority would do in this situation. Compression on the right side is 130 psi using the starter. The cylinder and the head from the side with the broken piston seem to be completely savable. So would you all just throw a piston and rings set in The one side and put it back together or would you put two new pistons in at the same time?
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Re: What to do?? Broke piston.

Post by URALNUT60 » Mon Jul 08, 2019 8:38 pm

First thing I would do is try and figure out what caused this meltdown, skirt to cylinder clearance, improper ring end gap, rubber intake cracked sucking air? Something caused this! I would at the very least tear down the other side for inspection, check for any signs of danger on the horizon, if the bad side can't be cleaned up and same size piston used I am doing both sides! Just me! At very least clean up good side readjust piston wrist pin fitment and new set of rings! Someone else will give you different answer! Good luck

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Re: What to do?? Broke piston.

Post by jeffsaline » Mon Jul 08, 2019 9:01 pm

A friend had the same thing happen last year on his 2008 Patrol that used to be mine. He had 80 psi on the left cylinder and 125 psi on the right cylinder.

He bought the correct size piston and rings, lightly honed the cylinder and put it together. It has been running well for the last year.


Jeff Saline
2010 Gear Up
-Good, Fast, Cheap. Pick Two
-Just because something isn't true, no reason you can't believe it. Hub McCann Second Hand Lions
-Anything is possible if you don't know what you are talking about.

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Re: What to do?? Broke piston.

Post by BillyG » Mon Jul 08, 2019 9:19 pm

It’s Russian. Slam a new piston and rings in and ride it like a scalded monkey to seat the rings. Screw honing it. Figure out why you were detonating (not pre-ignition damage) first...ignition timing too advanced? Low fuel flow (as black as that crown and head is...I doubt you were running lean)? Intake air leak? Low octane fuel?, Lugging engine up hill? If only that side was affected (after looking at other piston) that’ll narrow your suspects.
Bill Glaser
2002 Ural Patrol "CYKA"
300,000 km's since May 1st 2002
The "Unofficial Ural Service Manual" can be viewed at: http://www.myural.com

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Re: What to do?? Broke piston.

Post by Tomcatfixer » Mon Jul 08, 2019 9:49 pm

Fix what's broken first. If your rebuilt left side has 10% more compression than the right, THEN overhaul the right side.
- Chad

Gordonsville, Virginia, USA

Current rides:
2015 Ural cT "Mobile Chernobyl", 2001 Ural Patrol "Little Red Bear", 1999 Ural Tourist "The RPOC", Mid-Nineties Ural Tourist "The Heap", 1994 Honda VFR750F

Previous rides:
2007 Honda VTR1000 FireStorm (Super Hawk in U.S.)
2001 Buell Blast! - - - - - - - 2005 Yamaha FJR1300
1993 Honda CBR600F2 - -1984 Yamaha FJ1100
Two different 1986 Yamaha FZX700S Fazers

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