Just Isn't Right! cr250


20 replies to this topic
  • mikeaj92

Posted July 28, 2009 - 02:49 PM

#1

on my 2001 cr25o. I finished top end today, and seems like it went back right.
Has good Compression. idles high, yet never can get screw to make a big difference. and doesn't seem clean while idle. 1-3rd is nice, but seems like top power is sluggish. reeds are good, e valve is right, and carb is clean. any tips on setting mix screw right?

same jets worked before (420, 30, stck needle)

any ideas would be great!

  • mx730md

Posted July 28, 2009 - 02:51 PM

#2

did you put this piston in the right way? arrow toward the exhaust???

  • mikeaj92

Posted July 28, 2009 - 02:54 PM

#3

uhm. there was no arrow. but what way? open skirt side front or full side front, and how would this effect it (not that it doesn't). and I forgot to add, it revs alittle on its own. and checked for air leaks.

  • mx730md

Posted July 28, 2009 - 03:07 PM

#4

window should be towards the intake . solid side towards the exhaust. what kind of piston was it? ive never seen a piston with out a arrow on the top.

did you hook up the exhaust valve? that could be your sluggish topend

  • mikeaj92

Posted July 28, 2009 - 03:10 PM

#5

well that's a relief. thats how I put it in. its a stock new honda one. I looked for a arrow to. who knows.


Any recomedations on what to try for jetting? or needle? what way should I go?

  • marv02

Posted July 28, 2009 - 03:12 PM

#6

Whats you'r plug gapped at.

  • mikeaj92

Posted July 28, 2009 - 07:55 PM

#7

How about you tell me, what plug I should have, and what my gap should be. Since I dout either is okay........

  • marv02

Posted July 28, 2009 - 08:16 PM

#8

If the gap is to wide it will not run cleanly when reved out if it will at all .020 Is a good gap to have.

This also go's for the flywheel air gap should be set at .005.

Been down this road before it will drive you nuts trying to chase it down.

  • mikeaj92

Posted July 29, 2009 - 01:01 AM

#9

Okay. what plug is the right one? and quickly, how do I check this air gap, and adjust.

  • mjprice

Posted July 29, 2009 - 04:56 AM

#10

first off how was it running before the top end? did the sluglish 2nd happen after the top end? did you route the throttle cable correctly when you put it back together? I think the stock piston has an "e" printed on the top of it. sounds like you may have an air leak somewhere. start it up let it idle and spray wd40 around the air boot, reed cage & carb id the idle changes you have an air leak. set the air mix screw out i think it's 2 turns out (stock setting) ride the bike and fine tune from there. if it bogs turn it up if it bogs even more turn it the opposite way. if it hasitates you went to far. you need to give more details.

  • mikeaj92

Posted July 29, 2009 - 06:43 AM

#11

It hasn't ran well in past month. My compression was around 140. the cable is okay. I will check gap and few things, and check for a leak and i'll get back.

  • T-roy JK

Posted July 29, 2009 - 06:26 PM

#12

Is it still 140? thats low. whats your elevation? should be over 200 at sea level.
I'm still sorting mine out after a rebuild. it idles high and was surging. did the pressure test twice and it has no air leaks. mine has to be jetting, but do the test to find out.

  • mikeaj92

Posted July 29, 2009 - 06:38 PM

#13

oh no, my comp is now much higher. I was 140, and after top end, its alot harder. Yet I dnt have my tester right now. I changed gap from like .060 to the .020 so il test her in the morning, but if still off, i dont know what to do!!

  • DesertCR

Posted July 29, 2009 - 06:44 PM

#14

This also go's for the flywheel air gap should be set at .005.

Marv, can you elaborate on this, I've never heard of it.

  • marv02

Posted July 29, 2009 - 08:41 PM

#15

The Air gap between the Flywheel and the Pulsar Coil pick up needs to be set at .005.

Remove you stator cover you see a round cylinder type wheel thats the flywheel it self there's some raised area thats where you measure you'r air gap at when it rotation of the raised area is directly across from the pulsar pick up coil it self (NOT RUNNING) with a feeler gauge.

If not set correctly the bike will be hard to start or some time not start at all (No Spark) if the gap is way to big.

The bike will still start if even you not at .005 but half or full throttle the bike will fall on it's faces and not rev out sometimes it feels like it running out of gas then picks back up again and again untill you back out the gas and the bike run fine at mid to low throttle once again, The air gap is just towide it can't make enough spark to keep the bike running at high rpm's.

But once you try get get on the high rev's again it just alls on it's face.

Also Check you'r Plug Gap I found.020 Is a good gap to have.

  • Mikie1

Posted July 29, 2009 - 08:52 PM

#16

How long has your gas been sitting in the carb? My guess is your pilot jet is plugged. If your air screw is set in too far (trying to richen up to compensate for the plugged pilot...) you'll get the sluggish top end. If you were chasing jetting before you did the top-end job, you probably leaned out the pilot and/ or needle, right? It may need to be richened back up a bit.

  • DesertCR

Posted July 29, 2009 - 09:13 PM

#17

THanks for the heads up Marv, I'll check mine out soon.

  • mikeaj92

Posted July 29, 2009 - 10:15 PM

#18

My gas is brand new, and the carbs been emptied alot. I checked all, and I can see right through them, there not clogged. i'll also check this gap in my air.

  • T-roy JK

Posted July 30, 2009 - 06:02 PM

#19

If the gap is to wide it will not run cleanly when reved out if it will at all .020 Is a good gap to have.

This also go's for the flywheel air gap should be set at .005.

Been down this road before it will drive you nuts trying to chase it down.



Are you sure about that air gap? My clymer book says .018. If you've tried it and it works, let me know and I'll try it, my top end could be better.

  • marv02

Posted July 30, 2009 - 07:49 PM

#20

This is for my 1995 CR500 motor with a 1996 CR250 Igntion System.

And P/C pipe Rad valve so it can pull more Revs out of the motor.
Plg gpped at .020





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