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Old 01-29-2020, 08:26 AM
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Default Top end rebuild

Quick question. How do I know when it's time to rebuild the top end of my 01 cr250? Is it safe / recommended for someone that has never done this job before?
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Old 01-29-2020, 08:38 AM
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There are a couple things to look at when considering a top end rebuild. The first is compression, which requires a compression tester. Below 120psi and you're due for some work. The other thing you can do is look at the piston and cylinder through the intake and exhaust ports to look for obvious signs of problems - cracks in the piston skirt, deep gouges in the cylinder walls.
Is there a reason you think you might need a top end - excessive noise, loss of power? There are usually indicators that there is a problem or concern.
As far as doing the work yourself, it will depend on how mechanically inclined you are. A good service manual is worth it's weight in gold as it will have all the specs and procedures to follow. 2 strokes are a little more simple to work on, but yours does have a power valve in the cylinder that will complicate things a bit. Overall it's not a terribly difficult job, but one that requires some patience and attention to detail.
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Old 01-31-2020, 07:50 AM
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Everyone who has done it did it their first time at some point. So, yes, it is safe for someone to do it that has never done it. The caveat is if you are willing to find a suitable service manual. They are readily available in print and in pdf/digital form. Additionally, you'll want a set of metric wrenches, sockets, a 1/4" and 3/8" torque wrench, and feeler gauges. If you have those tools, that manual, and watch a couple of youtube videos to get a "feel" for it, you should be fine!
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Old 02-04-2020, 11:25 AM
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One sign that shows you have low compression is if the bike kicks over very easily compared to what it used to. Another sign is if the bike has a lot less power than it had before. Constantly fouling spark plugs is another warning sign. Also look for any leaking coolant, as that can lead to major problems if it is allowed to leak internally. If you experience these issues, it's time to, at the very least, do a compression test. To know more click here
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Old 02-05-2020, 08:36 AM
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Quote:
Originally Posted by RichardParker View Post
One sign that shows you have low compression is if the bike kicks over very easily compared to what it used to. Another sign is if the bike has a lot less power than it had before. Constantly fouling spark plugs is another warning sign. Also look for any leaking coolant, as that can lead to major problems if it is allowed to leak internally. If you experience these issues, it's time to, at the very least, do a compression test. To know more click here
While we certainly appreciate you sharing advice to help others, I'd like to ask that you stop posting that link in every comment you make unless it's actually relevant to the topic (which I've yet to find myself). Please review the forum rules you agreed to about spamming when you signed up for the site. Feel free to send me a PM if you have any questions.
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Old 03-13-2020, 10:41 PM
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The cylinder may shows signs that it needs to be re-plated.
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