2001 cr250 piston problems?

manray2112
Edited Date/Time 6/16/2015 7:11pm
I picked up this 2001 cr250 not to long ago. It has ran great and has lots of power. Until recently. I got on it today, rode it around slow until it warmed up. Then got on the throttle a little bit. It didn't seem as powerful as before. Then it started to make this terrible rattle so I shut the bike off. When I tried to start it, it took multiple kicks and gas to get it going. (Starts first kick normally) and it doesn't sound the same. It's not as healthy sounding. I have a video of what it sounds like but don't know how to share it. Unsure
this is my first 250 2 stroke.
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Paw Paw 271
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Paw Paw 271 6/15/2015 4:58pm
6/15/2015 4:58pm
Sounds like it's time for a tear down to find the problem.
Sounds like it could be excess wear on the piston and rings.

Paw Paw
manray2112 6/15/2015 5:31pm
6/15/2015 5:31pm
Paw Paw 271 wrote:
Sounds like it's time for a tear down to find the problem.
Sounds like it could be excess wear on the piston and rings.

Paw Paw
Took the carb off to check the reeds and found a chipped one. As my dad was looking into the cylinder we found a piece of piston...looKS like it's gonna be a project. Got any suggestions on what piston kits and reeds to get?
Paw Paw 271
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Paw Paw 271 6/15/2015 5:51pm
6/15/2015 5:51pm Edited Date/Time 6/15/2015 5:53pm
If you broke the piston, I would suggest a full tear down as most of the time pieces will also lodge in the crank and bearings.
A piston breaking is a sign of either excess wear on the piston ( did not change it as often and required) or worn cylinder creating excess piston slap.
Measure the cylinder and see if it's with in spec's. If not then it will need replating.
You will also need a service manual and a few tools , like a case splitter and a flywheel puller made for your bike specifically.
Expect to put in all new bearings and seals.

Paw Paw
manray2112 6/16/2015 4:45pm
6/16/2015 4:45pm
Paw Paw 271 wrote:
If you broke the piston, I would suggest a full tear down as most of the time pieces will also lodge in the crank and bearings...
If you broke the piston, I would suggest a full tear down as most of the time pieces will also lodge in the crank and bearings.
A piston breaking is a sign of either excess wear on the piston ( did not change it as often and required) or worn cylinder creating excess piston slap.
Measure the cylinder and see if it's with in spec's. If not then it will need replating.
You will also need a service manual and a few tools , like a case splitter and a flywheel puller made for your bike specifically.
Expect to put in all new bearings and seals.

Paw Paw


This is the piston and beside it is a little piece of it I found. I can see a small piece in the crank but there is obviously more missing. I can't find it in the bottom end and the cylinder/head look good. Is it possible that it blew out through the exhaust pipe?

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MOTODAD422
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MOTODAD422 6/16/2015 6:54pm
6/16/2015 6:54pm
Yes remove the pipe and shake. You must replace the lower rod and crank bearings,or your investment in a new piston could be risky.

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