rm 125 running rich. why?

[Necro]

howdy .

i have a 93 rm 125. i just rebuilt the whole motor top and bottom. new bearings and seals. its a stock rebuild. with about 3 hours on it.

the prob im having is its running mega rich. it wont start , fouls plugs and has no idle quality. its lacking in mid and upper rpm. it falls flat on its face and will flood out if i let it sit, while blipping the throttle.


ive already been thought the carb. set the floats . i re jetted it down to o. e specs. some one before me stepped the main to a 390 jet from a stock 360. im guessing on because it has a fmf pipe and silencer, that didnt help. but it did sound better. i have tried 2 carbs . both with the same results.

i have checked the coils and ignition system. but not the timing.it doesnt seem to be all that adjustable.

but i have found that the reeds are just a slight bit open . say a 1/16 th to 1/8 of a inch. is that normal? or can this be my problem.

i did clean out the power valve. it was a slight bit worn but did move ok. it didnt really have much adjustments. just a clock spring for tension. seemed pretty straight forward.

could it be a bad set of reeds. or should i look some where else.

thanks for any advise,
eric

 

[Senior KX Rider]

There should not be a gap between the reed petal and the reed block. I don't know that is what your problem is but they should fit tightly

 

[whitesands26]

Check your reeds....Also the weather has warmed up lately and some places much more than others...If the weather has warmed up considerably more than the last time you started the bike it will run richer....Warm temperatures thin the air out making your fuel to air ratio higher...Less air to a given volume of fuel = richer.

 

[Necro]

well for anyone who is interested. the reeds were my problem. i flipped them over so they stayed closed. now the bike kicks over on the first try and idles fine. also has great power with no upper rpm flutters.
the jetting was good but i stepped down 1 on the main . the bike is almsot as fast as my buddies 99 yz 125. not bad .

thanks for the help.