Valve sizes

[Builder611]

On a 196 CC clone engine with a 14cc ported head and ported stock appearing carb running on methanol, 1.2:1 ec roller rockers,26# springs, what would you expect the horsepower difference is between a 24/25mm valves and a 25/27mm valves? Everything is the same but the valves.

Thoughts?

 

[KartRacingLA]

I would expect half a hp or so. Depends on the "airflow" thru the exhaust and intake though if the current valves are the restrictor or the intake/exhaust is the restrictor

 

[Shorttrackthing]

On a 196 CC clone engine with a 14cc ported head and ported stock appearing carb running on methanol, 1.2:1 ec roller rockers,26# springs, what would you expect the horsepower difference is between a 24/25mm valves and a 25/27mm valves? Everything is the same but the valves.

Thoughts?

Better flow = more power, a bigger valve does give more flow but also a head ported professionally has the best flow

 

[kartboy63]

Barry Young!!!

 

[Freezeman]

When I read "Everything is the same but the valves." It makes me wonder if people think they can just install bigger valves with out installing bigger seats too?

 

[Chipg56]

When I read "Everything is the same but the valves." It makes me wonder if people think they can just install bigger valves with out installing bigger seats too?

Large valves can sometimes restrict flow as well, notably when the clearance between the head of the valve and the sides of the head and cylinder becomes limited (valve shrouding).