03 cr 250 is dialed in! runs perfect

hadleycat

Member
Feb 12, 2006
16
0
I have had this bike for 3 years. Over the winter I made a few small changes that turned the bike from sluggish and un responsive to crisp and powerful. the bike is much easier to ride now, because the power is so predictable and always there. Pulls beautifully right off the bottom. I am rarely using the clutch out of corners now. Last summer the bike had V-force reeds, fmf fatty with powercore silencer, stock plug, and 93 octane mixed with honda full synthetic. These are the changes I made 1. cut 3 inches off of the powercore silencer. 2. ngk br9eix sparkplug 3. installed s8 nozzle in carb. 4. Iam running torco 110 fuel. since I did all these changes at the same time without testing inbetween I cant say which changes affected the bike the most, but it runs perfectly now. My jetting has always been 400 main, 40 pilot, 38-70 needle, and 1st or 2nd clip on the needle. the airscrew is touchy I soldered a small piece of wire with a 90 degree bend onto my airscrew so I can adjust it without tools on the side of the track if necessary, although it is alot less finicky now. I got some useful information on this site when tuning this bike and am relating my experience in hopes that it may be helpful to someone else.
 

tyler_43

Member
Jun 22, 2007
126
0
why didn't you just buy an FMF shorty Silencer instead of cutting 3 inches off a normal powercore? Or did you get a deal on the powercore? Just wondering...
 

hadleycat

Member
Feb 12, 2006
16
0
I originally bought the the powercore because I figured it would be a little quieter than the shorty. When I started tuning the bike. I knew a shorty would give me a little more low end which the bike needed. so instead of shelling out a hundred bucks for a new silencer I took the powercore to the mitrebox
 

hadleycat

Member
Feb 12, 2006
16
0
I am looking at the recommendations from FMF that came with the pipe I bought. these are jetting specs with the pipe installed, but should be pretty close if you have a stock pipe. 2002 cr 250 main jet 380 , pilot jet 32.5 , needle stock , clip position 3rd , air screw 1.5 out. these are for sea level and 65-80 f temp. The air screw is very touchy. when you get your jetting real close ride the bike and turn the airscrew out until you get crisp acceleration. Now try letting off the gas as if you are going into a corner (you need to be actually riding the bike to do this as you wont be able to get it right revving it on the stand) if the motors rpms dont come down when you let off the throttle you have turned the airscrew out to far. once you tinker with it for a while you will get a feel for what I am trying to explain. After all this if you feel you have it jetted the best you can get it and it still is not running real crisp try running some torco 110. you can mix it 50/50 with pump gas (87 octane is suggested). This bike seems to like race gas
 

tyler_43

Member
Jun 22, 2007
126
0
ohh icic I didn't notice the "last summer the bike had" part.
But yeah I wouldn't run anything other than a shorty on a twostroker... they're great
 

_JOE_

~SPONSOR~
May 10, 2007
4,697
3
tyler_43 said:
ohh icic I didn't notice the "last summer the bike had" part.
But yeah I wouldn't run anything other than a shorty on a twostroker... they're great
If you don't mind the noise. Loud sucks.
 

steve.emma

Member
Oct 21, 2002
285
0
ive got vitually the same setup on my 02' cr250, and i dont think the shorty silencer is even that loud at all. definitly nowhere nearly as loud as the 4stroke bikes that race at my local track.
 

hadleycat

Member
Feb 12, 2006
16
0
I agree steve.emma it is not that loud. I couldn't tell a difference in noise when I cut the silencer down. The 4 strokes are so much louder, you can barely hear my bike when I am out on the track riding with them!
 

tyler_43

Member
Jun 22, 2007
126
0
yeah my yz125 with the shorty is under our 96db sound limit. It's fairly loud but I'm riding on a track far away from residential areas... if I was woods riding then sure I'd get a Q or something.
 
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