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CR lost it's power

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Feb 8, 2001
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#1
Today I went to ride my 2001 CR 250 and it has lost all it's power. The power loss is most noticeable in the bottom to mid range. I checked the spark plug and it had grey deposits all over it. I put a new spark plug in it and it was still powerless. I have about 40 hrs on it since it was new. Before this I have been fouling spark plugs like crazy. I run premium pump gas with Castrol oil at 38:1. I clean my air filter and change the bottom end oil religously and the bike has run great right up to today. what the heck could be wrong? :(
 

HLT

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#2
Sounds like you have a power valve stuck. The manual has a very good explanation of how to check it for correct operation. If it checks out OK, the next thing would be a compression check.
 
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Apr 22, 2001
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#3
After you cleaned and oil the filter, you might've accidentally left a little too much oil on the filter, which will cause your bike to run rich, and will run sluggish and feel like it's lacking power at certain range. One time I left a little too much oil on there, and the mid range was sluggish and lost power.

If you're fouling a lot of plugs, you are running too rich, check your jetting.
 
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#4
Another reason would be a clogged silencer if you have been running to rich of a jetting..might wanna check that out.
 
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Feb 29, 2000
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#6
I'm keeping an eye on this post. I just bought a slightly used 01 CR250. It runs great from mid to top but is a pig down low. I changed the pilot jet. It helped some but not much.

After the first ride I noticed lots of spooge. My guess is that this guy ran excessive oil with the poor jetting that comes from the factory. I'm starting to think that the cuprit might be in the powervalve.

If I were you I would check the powervalve. Your gear oil shouldn't have anything to with your condition unless you are leaking oil into your crankcase via a leaky seal.

I'm also curious as to wether you changed the stock jetting or not. That might have created your entire problem.
 
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#7
The jetting is completly stock. It worked great right up till now but the other day it was blowing some major spooge out the pipe onto the swingarm. Is it in need of a top end?
 
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Apr 2, 2001
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#8
You may need a new top end, but if the bike was running fine and it is now having problems then it is probably your powervalve. All you need to do is take the cap, 17mm head, off of the left-hand side of the motor and see if it is in the proper position. It should be lined up with the L when running and the H when you rev it up.

I had my powervavle stick open the other day, I could tell right away that something wasn’t right. The bike didn’t have as much snap off the bottom and it sounded different. So I checked the powervalve and sure enough it was stuck. Hope this helps.
 
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#9
If your powervalve is stuck one quick way of de gumming it is to pour in some gas with premix inside the side exaust cover and move the assembly back and forth until it moves freely again. You will need to get the gas out of your crank, pulling the plug and kicking it over for a few min. should take care of it. You could flip the bike up side down if you got crazy and dumped a bunch of fuel in there.

I know a buddy of mine has a 01 and jetting down low was way rich, I think that he runs a leaner needle and much leaner jetting than stock. It has great bottom end.
 
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#10
Checking the PV on the Honda is easy.
Pull off the cap on the left side of the engine.
Start the bike and make sure that the valve goes from the L to the H as you rev the motor. (The maula describes it better).

Also, if you were fouling plugs like crazy, the engine was not running fine. Could be jetting (stock is way to rich on pilot and needle). Also, you might do a compression test, might need a new top end.
 

dirt bike dave

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#11
derek,
Sounds to me like you might need a new piston. I've heard the '01 CR250s have short piston life - how many hours on yours? The gray deposits on your plug could be little bits of melted piston, and the loss of compression would first be noticed by a lack of low end power.

Good luck getting it sorted out.
 
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Feb 8, 2001
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#12
It has 50 hours on it. I removed the cylinder head and the top of the piston has no deformation but a little bit of black that polished off ok. I figure I might as well put a new piston in it while everything is apart. So would you all recommend Wiseco or OEM?
 
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#13
Well, I suppose while you are in there, I'd recommend a genuine Honda piston over a Wiseco, but frankly it's probably still in great shape unless it's been motoed for 50 hours, and even then...

If you still have stock jetting...how do you even ride it? Mine wouldn't even hardly start in the garage in 35 degree temps last winter with the stock jetting! I went four sizes leaner on the pilot, which is a 25, 400 on the main jet, and leaned out the needle jet (not easy to get ahold of, otherwise just move the clip up one notch on the needle), try that jetting and see what you think. On the main you might go 410 to be safe...the bottom end was the real problem here...
 
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Jul 30, 2001
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#14
Loss of bottom end...

If you are running the stock jetting, I have a hard time thinking you burned something up. Like the other responses, the powervalve will make a big difference on the bottom end if it's stuck open.
A friend of mine with a 2K CR didn't index the PV actuator properly trying to do a top end late one night and his bike had no bottom end. He thought it had to do with the reeds he had changed while doing the work but it turned out to be the PV was stuck open (H).
I rode it, it was a total light switch, no bottom and then everything. Hard to ride.
If you got some abnormal splooge at the same time as you noticed the power loss it could be you have a bad crank seal on the clutch side and you are pulling some gear oil through. You would have noticed extra smoke as well.

After you get it fixed, try rejetting and you may be suprised at how the bike runs. At sea level mine would barely run with stock jetting.

Good Luck,
Scott
 
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Jul 30, 2001
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#15
By the way....

I prefer the OEM pistons. I've always run an OEM in my CR's.
I'm running a Vertex in my kids KX-80 and so far so good but it's too early to tell.