Helping a friend with '06 YZ250F!!!....

[yami racer]

Hey Guys,

I am a YZ450F owner myself but had the oppurtunity to ride my friends 250f yesterday that he bought used. Its an '06 and the valve service was performed. All I can say is I could not get this bike to get out of its own way. It is sluggish from 0 to 1/4 throttle so we will play with the pilot jet tonight but also sluggish from 1/4 to 1/2 so we will look at main and needle and then finally way up in the RPMs the bike finally seems to get up and go. Its as if it is holding back for some reason. Again coming from the 450 world where you can just crack the throttle in any gear and the bike hauls is this just how the 250f's have to be ridden or should I be looking for something to be wrong?

It starts fine (1 kick most times) so a ruled out valves but maybe I should not. I have read a little about checking them after they are replaced which we have not but would out of spec valves cause it to run like this? Even in the higher RPMs it feels like it is just winding out. Any ideas where to start? Or are there no isssues and I am just used to a much more powerful bike?

Thanks for the help.....

[Alley Cat]

just sounds lean......everywhere........

[av]

Sounds like a jetting issue, make sure all of your jets are cleared including the air jets in the intake venturi. Once all of the jets have been cleaned and cleared, if you still have problems, then lean out the PJ and needle untill it starts and revs well from 0 to 1/2 throttle, then adjust the fuel screw, needle and the MJ to be just slightly on the rich side.

BTW, the 250Fs when properly jetted are no way sluggish bikes, they can be pretty beastly to handle too.

[av]

just sounds lean......everywhere........

The 06 YZ250Fs have been known to be on the rich side IMO. If the bike feels like it is bogging when you rev it as if you have a fouled plug then it is rich, if it is anemic and coughs trying to get more fuel as it revs, then it is lean. Jet accordingly...

[yami racer]

Thanks guys...I really figured that is the case....we will do the carb this weekend. I really thought the 250fs could and should be beastly to handle so once we work through getting it jetted properly I will let you know what we find

[DROB]

Also double check the cam timming and shim adjustment. It is posable the dealer that serviced the bike wasn't very carefull. Other folks on the site have stated shim adjustment issues following the recall service. ?

[s10racer4]

Also double check the cam timming and shim adjustment. It is posable the dealer that serviced the bike wasn't very carefull. Other folks on the site have stated shim adjustment issues following the recall service. ?

i noticed my 06 250f after the valve job is very sluggish... and now that i have a my Yoshi pipe on it, its very sluggish... i try and wheelie and it just bogs down? am i lean or rich? seems like i lost all my bottom end... bike really doesnt throw me around like a friends 450 did.. but i know a 250 and a 450 are way different

[adamdf]

hmm, this is making me wonder if this is my problem and not the high compression piston i installed while we were doing the valve replacement. i'm wondering now if my mechanic didn't screw something up, i was assuming jetting was off because of the piston but maybe its really the cam timing ? arggg

[bigred455]

Just because the motor starts up 1st kick, does not mean the valves should not be checked. Check those intakes,especially after a Yamaha technician serviced it! The valves should be checked regardless,just to rule them out. ?

[av]

hmm, this is making me wonder if this is my problem and not the high compression piston i installed while we were doing the valve replacement. i'm wondering now if my mechanic didn't screw something up, i was assuming jetting was off because of the piston but maybe its really the cam timing ? arggg

If your timing is off, the bike will run like crap no matter what you do with the jetting. Especially when it used to run great and had no jetting issues, definitely check your mechanic's work...

[intensem1rider]

Definitely check the mechanics work...the way is see it is..that guy is a bike mechanic for 1 of 2 reasons, 1 he loves his job and does it right, , or he's a high school dropout who took auto in high school, he's only working to support his gross wife, lol.

Check your mechanics work ?

[yami racer]

Thanks all....Will check the work but did let a local pro ride it last night and he said the bike absolutely rips...Hmmmm guess I am just used to the way the 450 pulls me around.