machining valve stem
Turbo Mini Forums

Evening folks,

I was wondering if it is a good idea to machine 2mm off the stem of STANDARD inlet valve in the area that is not in the guide for extra airflow ?

I seem to remember there is a small stem setup available from a famous company but I assume the valves are fancy items.

5 mm is standard japanese bikes stem size, yes, air cooled ones !

Did some crude calculations and extra area provided should gives 1,5 hp on a 998, not something to disconsider given the work involved.

Rusty by nature

just use the stainless race valves readily available with wasted stems,

there are many factors involved and depends on what thier made of ? the valve you going to machine ........ bike valves are usuall not turbo charged

1.5 hp for unknown reliability is not worth it in the least IMO.

Another way to put it...

Have you ever seen the destruction a dropped valve can do ?

It's impressive !

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

Mmm id be looking At those valves swifty or med do the s6? Ones they are skinny and use diffrent guides and seals but expencive

Think id just put an extra psi up her and call it as good as the gain in efficancy

Cheers gents.

I'm on the look-out for cheap HP out of a N/A 998 for a friendly hill-climb so this sounded nice.
But yes, reliability is still important.

Rusty by nature

http://russellengineering.com.au/performance-cylinder-heads/

a worthwhile read of you are into (na) 998

i'm working on a 202 head and will test 1275 valves ground down to 32 mm on the flowbench. As i have a load of good 33 from 1275 upgrades they are free

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/