Polaris Indy 600 2015 no fire on one spark plug what can be the cause

[na_gagnon]

Hello, I was driving my Polaris and suddenly the RPM dropped, I stopped open the side and saw that one spark plug was disconnected. I came back home at low speed and changed the spark plug, changed the spark plug cable but still low RPM, new spark plug does not seem to be working, so I changed the spark plug to try it on the other side and the spark plug works. I have made another test I took the cable of the first spark plug and it worked. Although I still have this issue of low RPM, do you have any advise on what to check to understand the cause of the issue and how I can fix that/ Thanks

 

[obob]

So, do you have spark on the side you are concerned about?
Do a compression test.