I fitted a 80cc bigbore kit to my direct bike's DB50QT-32 Viper50cc and it was perfect with extra power but now after only a few weeks, the power seems to be lacking at times, basically back to standard sizebore power,but it gives me power spurts as and when it seems to feel like it,can anyone explain why please

Dave, February 2017

It's your carb needs re jetting probably 5 sizes bigger.

Andy H, March 2017

now that you've run it a few miles have you re-torqued the head down and re-checked the valve clearances and/or followed the kit makers instructions? might be losing compression somewhere if not, apart from that it may just be that you've got used to the power already.

peter o'toolbox, February 2017