valves???? no i dont think so . it cant hurt to check them but your going to need a shim kit to adjust them . if it will start and run its some thing more likely with the carb.
did you say you had the carb apart to rejet ? what size jets did you put in and what kind of jets did you use? and were did you have the fuel screw set at ?

 

the jet kit i have is the FMF powerup kit from dynojet. the first time i jetted it i used a 134 main jet with the needle on the 3rd clip. and the mixture screw out 3 turns. and it still kept doing the same thing. so i played with the mixture screw a lil and it didnt help. so i tried a 150 main jet and it still kept doing the same thing. then i tried the needle on the 4th clip and it was still doing the same thing. so i got frustrated and put the stock exhaust back on and the stock jets. and it still keeps doing the same thing. it'll start run for a while and then die. then it wont really want to start and if it does itas not for long.

 

if you will look at this list your going to see that by using a 134 DJ is that you went smaller in size than what the stock jet was that you had in the carb in the first place .
by using a 150 DJ its like using a 140 mikuni which is still to small (lean).
a 160 -166 DJ should get you in the ball park
Width------Keihin # -- DynoJet # -- Mikuni #

0.0540---- 140--------- 130--------- 121.9
0.0550---- 142.5------- 132--------- 123.8
0.0560---- 145--------- 134--------- 125.6
0.0570---- 147.5------- 136--------- 127.5
0.0580---- 150--------- 138--------- 129.4
0.0590---- 152.5------- 140--------- 131.3
0.0600---- 155--------- 142--------- 133.1
0.0610---- 157.5------- 144--------- 135.0
0.0620---- 160--------- 146--------- 136.9
0.0630---- 162.5------- 148--------- 138.8
0.0640---- 165--------- 150--------- 140.6
0.0650---- 167.5------- 152--------- 142.5
0.0660---- 170--------- 154--------- 144.4
0.0670---- 172.5------- 156--------- 146.3
0.0680---- 175--------- 158--------- 148.1
0.0690---- 177.5------- 160--------- 150.0
0.0700---- 180--------- 162--------- 151.9
0.0710---- 182.5------- 164--------- 153.8
0.0720---- 185--------- 166--------- 155.6
0.0730---- 187.5------- 168--------- 157.5
0.0740---- 190--------- 170--------- 159.4
0.0750---- 192.5------- 172--------- 161.3
0.0760---- 195--------- 174--------- 163.1

 

where do you find good charts like that? i have looked and couldnt find anything. i didnt realize that the sizes where different by brand. thats good to know, thanks for that info. now i just need to get the thing running and then ill put the exhaust back on and rejet it.

 

you may find as well that the pilot jet will have to be bump up to a #25.
you will know if it takes more than 3 1/2 turns out to clear up the idle and the hesitation at low RPM's.
as well there may be a red header pipe which means a lean condition.