I was sitting here thinking about engines and had a thought. When I was young, my dad and some of his buddies were hogging out a cam journal to install needle bearings. Never really thought much into it until I installed my big bore kit. Is there any horsepower to be gained from roller bearings in the camshaft of these small engines? I don't plan on doing any machining. I am just curious.

 

not significant enough to warrant the work and cost

 

My guess is if there were enough horsepower lost there (due to friction) to make a noticeable difference, they would melt down pronto. Just a guess though.

The mod has been discussed by others when journals failed due to lack of oil.

 

Plain bearings run on a film of oil - extremely low friction with the kind of oils now available. Even the cheap stuff, considering the additive package in the blend.

Virtually all super sport bikes and muscle cars as well as the racing versions are running plain bearings. I guarantee you if and race team could eek out a 1% horsepower gain for racing they'd have ball or roller bearing crank or cam journals. It doesn't and they don't.

 

probably not since most engines, even performance ones still use plain bearings for cams.

Now roller cams.... that is worth power, and why you have seen flat tappet cams phased out in automotive engines. Why its not done in bikes...probably cost and also packaging size