yz144 help with motor

tj816
Posts
9
Joined
5/23/2017
Location
Merrick, NY US
5/23/2017 4:44pm Edited Date/Time 5/26/2017 9:06am
whats up I was wondering if anyone else had the same problem as me with a yz 144 kit (ATHENA). I had the bike for a few years with a 144 kit and never blew up like It did the other day. I hit a jump and the bike locked up in the air, thank god I was ok. I thought the crank went so I cleaned the bike and started breaking it down. When I took it apart the head was detonated and the piston was melted to the cylinder.the crank looked brand new and there was no play in it. I will show pic that follow. the bike runs on 50/50 pump and race gas and has a pro circuit pipe. Thank You.









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Paw Paw 271
Posts
3640
Joined
4/3/2013
Location
Benton, LA US
5/23/2017 7:10pm
Looks like the lower crank rod bearing has broken and caused havic. No signs of detonation in photos.

Paw Paw
tj816
Posts
9
Joined
5/23/2017
Location
Merrick, NY US
5/23/2017 7:53pm
Looks like the lower crank rod bearing has broken and caused havic. No signs of detonation in photos.

Paw Paw
I checked the crank its in spec
Acidreamer
Posts
1794
Joined
8/25/2015
Location
Mansfield, OH US
5/24/2017 9:32am
Something below the piston failed. Wrist pin bearing or a bearing in the crank. I cant think of anything else that would have done that. Just because your crank is in spec doesnt mean a peice of a bearing didnt pop out and fuck shit up.
5/25/2017 12:49pm
Yep. Bearing let go somewhere. Guessing the wrist pin. Had that happen on my quad years back and the damage looks very similar

The Shop

Paw Paw
Posts
679
Joined
12/24/2011
Location
Benton, LA US
5/26/2017 9:05am
After looking at the photos again....I see what looks like a piece of the cylinder missing in the first photo.
When was the piston last changed?

Paw Paw

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