You should post a video so people can see/hear what the issue is.
Most likely you're using the wrong microphone for the job. When you're speeding wind resistance causes excessive noise which overdrives the microphone at which point sound will start to cut out. So most likely the cackling you're hearing is the sound cutting in and out.
Most well produced Vlogging video's actually use a number of mics for audio. One to capture voice recording, 1 for low speed engine noises and 1 for high speed travel that has proper buffer protection from the wind.
Here is the sample audio of my hero7 black.
So your video just proves that the audio is cutting out due to the microphone being over driven.
Have you checked the audio settings on your friends camera, have you checked to see if they have the microphone mounted in the same location, do they use the same type of helmet, are they using the same type of bike, are both engines tuned the same?
I would suggest you invest in a decible meter so you can run a true comparrison on audio levels and see how much more noise you're generating. Actually, if you're trying to get a good recording of your voice, your microphone shouldn't be picking up any engine noise or wind noise regardless of volume or speed. Since your microphone is picking up both windnoise and engine noise, that's just proof that it's the wrong microphone for the job.
You may also want to post a picture of your setup to help solve the issue. Where the microphone is mounted, how it's mounted, what types of wind/noise reduction you are using. That way we might be able to make some suggestions for you to try out. Love the night video of the motorbike though, looks good, so lets try to make it awesome!