250R crapping out on topend

[Fox250R]

38 a/s ,radvalve,ported,no airbox bored .10 40-1 hp2 with 110 racing fuel,eunning a br9es...pilot is 55,mail is 178 needle is 2 slot.

[Fox250R]

your air screw will have nothing to do with top end.your rich on the main drop to a 170-172.if your gonna jet go atleast 1 size at a time.thats two jets lower,would equal i size,the others are half sizes.it's breaking up at full throttle right?

Yes when i pin the thottle its crapping out..

[cr500=3wheeler]

Any compression mods ie thinner head jasket,cut cylinder head. etc i realize this is not the direction you where going but im wondering about the 110 octane to me it sounds like wasted money but hey, as far as the other question id keep going down in jet size, sounds like its fat to me, what altitude are you at. The other question is was it running good with the other carb might be an ignition problem but id bet its just fat.

[deathman53]

well, low end reeds and a top end pipe are gonna be part of the problem, but not enough to make that much of a difference, it sounds as it has port work done to it. A low end pipe would help, if thats what you want.

[OldManDM]

sounds like the same thing mine does,and i`m clueless,lol......don`t know squat about messin with jets and all

[Dammit!]

This ain't that complicated. It's too rich. Dark brown is too rich. Sputtering at WOT is too rich. It isn't the rad valve or anything else. Go down to about a 172 and if the problem isn't gone it's gonna be much better and you'll have a better idea of what's going on. Check the plug and go from there.

Edit: that 55 pilot is probably richer than it needs to be too. If it's not snapping off idle real good lean that out as well. Is the needle in the 2nd position from the top or the bottom?

[Fox250R]

This ain't that complicated. It's too rich. Dark brown is too rich. Sputtering at WOT is too rich. It isn't the rad valve or anything else. Go down to about a 172 and if the problem isn't gone it's gonna be much better and you'll have a better idea of what's going on. Check the plug and go from there.

Edit: that 55 pilot is probably richer than it needs to be too. If it's not snapping off idle real good lean that out as well. Is the needle in the 2nd position from the top or the bottom?

From the top............I just went to honda and got a 172 main and a 52 slow...Lets see what happens now :

[wanta86r]

make sure you only change one jet at a time. dont do both changes at once

[Fox250R]

yeah ill make sure i do that....THanks man

[3leggeddog]

jet er down bud and things will be fine.drop a 172 in there and do the plug chop like i told ya.report back after that.

[Fox250R]

Well, i put a 172 in and 2 turns out on the air screw and running a br8es...My plugs are coming out light tan and its stopped spuddering on the topend..i rode a wheelie from 1st to 5th down my street till i ran out of room, otherwise i could of hit 6th lol..So i guess its running good now..The only prob is when i pull the choke it still runs the same...Im not sure if this is a big deal but it starts 2nd kick everytime and when i let off the gas it comes down to a perfect idle..I think its running a litte rich but that ok with me....Thanks for all the feedback on this! you guys really helped me out.................

[OldManDM]

yea,i was running the stock 142 in mine and went and picked up a 140 and a 138 today at Honda....put the 140 in and it seems to be running better now....i just wouldn`t know how to tune this thing right if my life depended on it,LOL

[Fox250R]

well its not to tough if you read your plugs...I was having probs trying to get this stryker tuned..I listened to the guys at honda witch proved to be a HUGE mistake..Just post what your trying to do to your R and these guys out here will get you on the right track...They did me!!

[3leggeddog]

glad we could help bro,shoot me your carb troubles anytime,sometimes i may help,other times i may not.

[Fox250R]

glad we could help bro,shoot me your carb troubles anytime,sometimes i may help,other times i may not.

Well i finally got to take my R to a wide open space and open it up..Low and behold its still doing the sput sput sput at the topend..Its running much much better then what it was ,but i was wondering could i drop another size to a 170? or just leave it as it is and see if it might clear out after a few runs...THANKS!!