I have a 2005 trx 450. I am having engine problems here recently. What is happening is when i get up in the higher gears (2 3 4) and i hammer the throttle it stalls. I won't accelerate, it just stalls. I can ease through the gear and it will run fine. When i first get on the throttle the engine makes a rattling sound. The bike runs perfect in first gear. I just have the problem in the higher gears. Whats your advice?

SOURCE: Bike shuts off when in gear

hello and welcome
it seems that you may have a faulty side stand switch. the side stand needs to be in the up position before the bike can be started off in gear. but if not the side stand contains a saftety switch that shuts the bike off when put into gear. to verify this you can check for spark when the bike is being turned over in gear with the clutch held in.
there should be two wires associated with this switch. a green, and green with white. so when the stand is up these two wires are connected, and the switch can be tested as such. thank you.

SOURCE: i have a 1990 honda 300 four trax 2x4 and a nice bike good shape

Good news > save your money on the clutch. Bad news > Invest it in new shift forks. What you describe is a standard symptom of bent shift forks. Sorry to be the one to tell you this.

SOURCE: bike revs up

the clutch is slipping under load. time for a new one.

SOURCE: Honda V1100 Jumps out of gear on full throttle acceleration

More likely it is a slightly bent shift fork not fully engaging into second. The clutch and bearings are not suspect. Remove your foot from the shift lever then go full throttle in 2nd. Those new riding boots may be doing the magic unconsciously. Adjust the shift lever height if that is the problem.

SOURCE: 02 crf450r starts up fine.... let choke off then

I have a crf 250 R and i have learned multiple things about these bikes like if you leave it running and not riding it for about ten min. it will over heat. they love race gas 113 octane,and alot more. but your prob sounds strange. i know if you hold the hot start while its runing it pops that could be a problem. or it could be you are not cleaning the bike out i would need to know more about this to give a definate answer but try going over the bike. Look at key parts like the
carb
air cleaner
fuel line
any thing that is nesessary for the bike to run.