2000 CR250r Low end power

13 replies to this topic
  • luckyguy19

Posted October 19, 2009 - 08:48 AM


[COLOR=black]Hello all, [/COLOR]
[COLOR=black] [/COLOR]
[COLOR=black]I’m new to this forum, just picked up a 2000 CR250r, my first two stroke. [/COLOR]
[COLOR=black] [/COLOR]
[COLOR=black]The bike runs great, it screams up top, it hits very hard. But I’m getting tired faster trying to hang on when the power hits. Coming from four strokes, I know it will never have the same low end, but I'm willing to sacrifice some of the top end to get back a little low end. The bike already has an FMF Gnarly pipe, and a Boysen power valve cover, I know both are suppose to help low end. The previous owner told me it had a Pro Circuit cylinder head, will swapping out to a stock one bring back the low end power? Any other suggestions? [/COLOR]
[COLOR=black] [/COLOR]
[COLOR=black]Being new to two stokes, I’m not quite sure where to start. [/COLOR]

  • Dirk_D

Posted October 19, 2009 - 09:58 AM


does it have the stock reed cage? I just put on a vForce3 cage/reeds from stock while freshening the top end & it's a whole new animal - the top end is insane now. You might consider going back to the stock reed cage if it's not there already..... I think that's where my power came from but it may be a combo of reed cage/reeds & piston. hth

  • frdbtr

Posted October 19, 2009 - 11:32 AM


A heavy flywheel will smooth out the hit as well. get one that is at least 13 oz heavier then stock.

  • luckyguy19

Posted October 19, 2009 - 11:45 AM


It has V-Force reeds right now.

  • Jrs Turn

Posted October 19, 2009 - 07:53 PM


Are you trying to get a bit more torque down low? If so, you can add a tooth or two to the rear. It will slow your top speed a touch but will change how it reacts down low. Good year choice too!:bonk:

  • luckyguy19

Posted October 19, 2009 - 08:23 PM


Yeah, I really dig this bike. It needs some new plastics and graphics, its been sitting outside for the last year. With a little work its going to be a great all around bike. I should have it set up for the woods by next spring, its just a desert bike right now.

  • DeeCee

Posted October 20, 2009 - 02:23 AM


I had a similar experience with my 2001 CR250. I came from a YZ400F. What I found was the jetting was way too rich, especially in the needle range. I fitted a JD Jetting kit and what a difference. The bike will actually lug from low revs, not like a 4T but it will pull away rather than just die.

This certainly made riding the bike much easier and less tiring.

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  • luckyguy19

Posted October 20, 2009 - 06:20 AM


Thanks, I think I'll try a JD jet kit. I have one on my YZ250f, it runs great. I know the jetting is stock, and we're at 5000ft elevation.

  • T-roy JK

Posted October 20, 2009 - 08:07 PM


+1 on the JD kit. I'd also check the compression. not sure what it should be at 5000ft. mine is 225 at sea level tho.

Oh, and check the exhaust valve. take off the 17mm bolt/cover on the left side of cylinder. it sould point to the L until mid rpms then rotate to the H.:bonk:

  • 2bitsamile

Posted October 20, 2009 - 10:55 PM


advance timing a few degrees. You will need to file screw hole in stator mounting plate as that limits timing advance/retard from std

check squish, maybe bump compression at same time

Boyeson Pro Series 2 stage carbon reeds

spacer on reed cage

shorty silencer

swap in cylinder from a '99, or have your ported for low end

  • luckyguy19

Posted October 24, 2009 - 01:52 PM


It turned out to be the power valve. I took off the 17mm bolt on the left, and the line was stuck at the H (high) mark, it wouldn't move at all. I took off the cover on the right, turns out the linkage needed to be adjusted. Now it stays at the L (low) then goes to the H when reved hard, returns back as the RPMs fall. Night and day difference. Can't wait to go ride tommorrow, now it has almost as much down low as my YZ250f. Should be much easier to ride.

  • luckyguy19

Posted October 24, 2009 - 02:50 PM


I have a question, should the power valve spring back to the L position. It goes back to the L and goes to H when I rev it, but It dosen't snap back to the L position, it goes back as the RPMs come down, is this correct. Also when I have the right side cover off, the valve dosen't seem to act against the spring as I rotate the lever by hand from L to H, but if it goes a little past the H you can feel it push against the spring tension. It almost feels like the whole range between L and H has no spring tension, is this correct???

  • PeterJ

Posted October 24, 2009 - 05:26 PM


On my '95, the power valve switches pretty fast both ways at about mid rpm. When I checked it, I expected it to have a much slower transition. I've never tried turning it by hand so I can not help there.

If you ever get a chance to try a stock pipe, do it. I think the power is way smoother than a FMF Gnarly pipe on the '00 CR250. Also, +1 on the flywheel weight suggestion.

  • luckyguy19

Posted November 24, 2009 - 08:29 AM


It was the power valve. At some point in time it was put back together wrong. The valve was adjusted so there was no spring tension, it would just flap around. So while it would move, once the motor warmed up it was stuck on High. That is why I had no bottom end, the valve would move to High barley off idle, instead of later on in the RPM range. The huge hit was fun, but made me tired too fast.

I took the right side case cover off and found the rack was not installed correctly with the pinion. It took me 30min just to clean off the orange RTV that was caked on everywhere. Put it back together with fresh gaskets, adjusted the valve so it had spring tension on it.

As soon as I got to the end of the street and ripped on it I knew it was fixed, finally. It’s like riding a different bike. I took my 5 year old daughter out riding the next day and was able to lug it and go slow with her, would have been impossible before. It will almost idle up short steep hills now. Thanks for all the suggestions, there's a wealth of info here.

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