'04 CRF250/Kibblewhites/Yoshi

[steelemx]

Hello,

In advance I appreciate your help.

I have an '04 CRF250R

I Just put New rings on a stock piston, had my head ported and polished, the valve seats cut for the SS kibblewhite valves and springs. I also run a Full Yoshi Pipe and silencer, Carbon Fiber Version. I am now getting a bog at take off from the line. or when I "blip" the throttle. My carb is set up all stock with the clip on #4 and the pilot screw 2.25 turns out. With all stock jetting.

Slow Jet = 40, Main jet 155. The Spark plug reading apears to be lean. (white)

Adjustment or jet it?

Any ideas?

Thanks

Travis

?

[Wayward Son]

155 main jet?at sea level?

[steelemx]

Thanks for the response!

Elevations in the county range from 382 to 850 feet above sea level.

Dallas Texas.

My service manual says the main is 155 Stock. I havent taken the carb apart to confirm I did replace the accelerator pump that was foul.

Please Advise,

Thanks again,

Travis

[steelemx]

My mistake My mainjet is a 160. Verified.

[steelemx]

Is this the correct jetting ?

[Wayward Son]

that is correct.

[steelemx]

Any suggestions on the bog when I start or blip the throttle? since my jetting seems ok? I keep hearing since the head was polished and ported with the full pipe it would need a bigger jet or jets. Heck the Honda dealer handed me a 45 slow jet, and said try this lol.

thanks

Travis

[Wayward Son]

better or worse when hot?

[steelemx]

close to the same. I was on the line, Only started it to go to the gate, and before the gate dropped. When the gate dropped and I stabbed it it died and was hard to start. I Got it started, finished the moto, go back to the truck , kill it, and it starts right up. go figure huh.

It seems to bog on the stand when I blip the throttle hot or not. Unless I roll into it.

Thanks very much. I was thinking of moving the clip to the next lower setting?

I can try it at practice tonite? good idea?

Thanks

Travis

[kevin204]

Sounds like the AP timing.... my Yamaha did the same thing, and I know many '06 CRF's do.

[steelemx]

WEll I moved the Clip down one and turned the pilot screw out a quarter turn and went to practice tonite. The bog was nearly gone. however speed seemed lacking. Also while waiting for the green flag at practice at the gate not for more than 2 minutes maybe 3 I looked down and the header is red. not glowing but pretty red. Naturally it turned back to the original color once rolling. Please advise as I want to get it right. As far as the AP Timing. Does that adjust at the top area of the shaft?

The plug was copperish with a little white on one side. fyi

Thanks

Travis

[steelemx]

chello?

[Wayward Son]

the head pipe glow is normal in no air flow.

try a 158 main jet.

[steelemx]

Thanks I will try the 158 and post the outcome. should I move the clip back to 4 and the pilot screw back to stock?

[Wayward Son]

leave the rest.