The main issue is getting at it to drift it out. The frame rail is in the way unfortunately

Should push out from the other side. I had this problem and in the end resorted to cutting it out and buying a used relay arm.
The bearings were rusted solid on mine

What's the spark plug look like? Have you checked/cleaned the air filter? Is the exhaust blowing?

Did you rejet or adjust the carb to suit the big bore kit?

@BlueMoto yes I've got one on mine. Works a treat - bit of wiring to do and I made a mounting plate as the one you get with it is a bit naff.

Not a huge job though

@NINJA maybe you just didn't use them right worked a treat for me

@NINJA do you have any experience to back up your broad sweeping statement?

@britshgigolo let's hope so

I used some of that anti puncture fluid on my old Suzuki - you have to take the valve out then fill the tube, valve back in and inflate. I don't think either tyre ever lost air between then and selling it

This isn't what I used but it's similar.
https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.co.uk%2Fulk%2Fitm%2F133033492866

Had a YSS on an old bike and it was sound. No experience of the others I'm afraid