84 250r 2 questions possibly easy answers pls help

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Hey guys here my problem. I can go through all my gears once I get up to the top end of fifth it seems to stop giving me power but every once and a while it takes off like a bat out of hell weird right
So i can be doing 80km then next thing u know it wants to take off. Is it not getting enough gas or is it by getting to much. Or maybe the coil? Any ideas

2nd my clutch lever is too tight how do I loosen that up , replace the cable or is there an adjustment for it.

Thanks for your help

[86ATC 250r]

replace the cable there only like 15 bucks. mine is the same way so i gotta do that soon. and on my 400ex it was so hard to pull like my hand was killing me with in 5 mins of rideing. i replaced cable now i can pull it in with my pinky.