Hey guys, it's been a while since I have been on here, but I need some help with an old/renewed project bike.....2002 Honda CR250 basketcase that I picked up 1 1/2 yrs ago for cheap.  I had the crank rebuilt, put a new top end and all new gaskets.  I attempted to rejet the stock carb, but the bike would not "get on the pipe"....It would just seem to stumble....I replaced the RC valve cables, same issue.  I swapped to the PWK Airstriker carb and still have the same no p-band issue.  If I safety wire the RC valve WFO she rips like nobody's business but has no bottom end...........I tested the RC valve servo motor per the oem manual instructions an I get a constant 5.75 ohm reading which is right in the middle of the spec chart both with 12 volts and without.  My question is, I think the only other thing it could be is the ECU/CDI...Is there a way to test that?  No mention of testing it in the service manual.....


Thanks in advance,
-Craig

Damn.....Nobody knows how to test the CDI box on this bike?  I don't see anything in the manual about testing it......Maybe I will just have to buy another one....Unless somebody would be willing to put my CDI box on their 02-03 CR 250 and see if runs crappy like mine does......

ok..well first take the RC cover off.. and rev the bike up. does the powervalve open? if so thats not your problem.. and to test your CDI you hook a voltometer up to somwhere i cant remember.. a service manual will show you

I have taken the cover off and revved the bike....the valve wil open but only partially.  Almost like the servo motor does not have enough power to open it the whole way up.  I tested the RC servo motor per the manual instructions.....When I hook it up to 12v, the valve opens all the way....reverse the polarity and it closes completely as it should........with an ohm resistance right in the middle of the spec chart.  I have looked through the manual but I don't see any tests to be done on the ECU itself.....


-Also, the valve opens and closes with no issues by hand.....when I disconnect the cables to the butterfly and rev the motor, it still only turns the servo partially, not the whole way like when I put 12 volts directly to it.

-My theory is that the ECU is not sending sufficient power to the servo motor and therefore, it is not opening up the ex valve completely.......

Is this the same setup as the 05-07? If not then disregard this, but anyway this is for 05-07

The valve should start to open (Lift off the seat)at 4K RPM and open fully at 8K RPM
You need to check the voltage at the servo motor at 8K to verify your theory.
Also, check all the connections from the ECU to the servo motor for corrosion


Just thought of another possibility, the resistance value is not in the manual, but if the servo assembly was taken apart prior and if the feedback resistor gear was not set correctly then the wrong feedback voltage could be getting to back the ECU.

Edited by AXAxiom, 27 May 2012 - 01:12 PM.

Thanks for the suggestions.  I will be going over each and every connection on the bike to check for corrosion and proper cleaning with OD electrical contact spray.  As I remember, the 02-04 models had the same design, the 05 and newer had a different parts schematic.  I bough this as a basketcase, so I have no idea personally how she ran before the motor seized.  This was the 1st top and bottom complete rebuild that I have done.  I rechecked to be sure that I did not miss anything and I am pretty confident that I didn't miss anything.  Do the ECU's on bikes just "go bad"?

Have you checked that the cables are adjusted correctly?

Yup, used the 12mm method at the rear barrel adjuster.  Once adjusted, I can move the butterfly both open and closed with some resistance with one hand...........


-Maybe a stupid question, but WFO should put the butterfly locked in a clockwise position resting against the stopper pin, right?

reason that i ask, is that the manual refers to a closed flapper valve at less than 3000 rpms, but shows a picture of the butterfly locked clockwise (Which I am under the impression is  wide open),  and fully open flapper valve when above 8000 rpms, but shows a picture of the butterfly locked in a counterclockwise position??????

Edited by craigs449, 28 May 2012 - 07:24 AM.

Pull the pipe and look,
05-07 CW=Closed and CCW= Open

This may sound stupid.....But, is there any way that I could have the servo motor running in reverse?  Almost seems like it gets the rpm's up and then retards the powerband......I just dont see how I could have accidentally done this?  Although she was a basketcase, the servo motor only goes on one way, the plug only plugs in one way, and the cables will only go to one side without crossing them.......The above post and the pics in the manual are making me think the servo motor is running opposite of what it should.......&%$#@!?

Anything is possible with a bike that had a previous owner.

Did you have any issues or questions adjusting it?
So are you saying that if you turn the valve full CW and start the bike it moves back CCW with small rev's? (way below 4K)
You should see the butterfly finding and pushing against the CW stop with revs under 4K.

Edited by AXAxiom, 28 May 2012 - 04:25 PM.

I just retested the servo motor per the oem manual.  It is hooked up right...thank goodness!.  When the manual says it should turn counterclockwise with 12v, it does.......Now I just gotta figure out why she is still not hitting the pipe........