What's causing this?

So I'm riding my bike today it's going good from 0-70 hit around 75 , 80 and it starts acting like it's running out of gas. Hit 90 and it starts running great hit 100 and it's pulling like it just got a boost of nitrous. So I slowed down to 70 and tried again with the same reactions.

Is your bike stock or modified on the intake or exhaust side? If so, could be a jetting issue.

If this is a new issue and the carbs have not been recently modified I would suspect some dirt is lodged somewhere. Otherwise....

It sounds to me like you're getting too much fuel in the mid range, where fuel is controlled by the needles.

Check that your ignition advancer isn't sticking

This a new issue that just started and nothing has been changed. It only happens between 75- 90 and only in sixth gear. A few months ago I changed my ignition the advancer was working good but I didn't clean it maybe it is sticking. One of my spark plug cables didn't seam to be fully seated in the coil. Could that cause this kind of issue ?

There is an easy way to find out

I think it was the spark plug cable. Now that the rain stopped I was able to go for a ride and the issue seems to be gone

Finding the problem is certainly satisfying. That it was cheap and easy is ice cream on the pie.

(I like pie and ice cream much more than cake and icing.)