More revs..

[EVLTWN]

How high can you realistically rev a stock xb 12? Assuming the factory rev limit was removed. With peak power occuring right near the limiter it seems some quicker times(drag racing) could be had with a little over rev room after the power peak before the limiter kicks in. What components Are the reason for the limiter? Will the valvetrain support higher revs? what won't?

 

[LeFox]

my peak power is round 5300rpm...

think you want a higher reving engine, you shouldn't have taken the hd based buell [smirk]

 

[EVLTWN]

mine pulls hard all the way to the limiter so i was just curious what it would take to get another 500-1000 rpm out of it? Do the xb9's use the same valvetrain as the xb12's?

 

[midlifecrisis]

The 1203 motor is a stroked 984 engine. High revving engines have a larger bore. Stroking a motor (the traditional Harley mod) increases torque and limits the RPM ceiling. Each revolution the piston needs to travel a certain distance, by stroking it you are increasing the distance (and speed) of the piston for the same RPM. Remember records? You know, vinyl LP's? Just as the entire record is moving at 33 RPM, the outer rim needs to travel further within the same time, thus increasing the relative speed. see Calvin and Hobbes.lol

 

[LeFox]

mine pulls hard all the way to the limiter

yea...but you still have a peak, somwhere around 5000rpm

 

[midlifecrisis]

Calvin and Hobbes, June 5th, 1990.
http://www.marcellosendos.ch/comics/ch/1990/06/199006.html

 

[EVLTWN]

The 1203 motor is a stroked 984 engine. High revving engines have a larger bore. Stroking a motor (the traditional Harley mod) increases torque and limits the RPM ceiling. Each revolution the piston needs to travel a certain distance, by stroking it you are increasing the distance (and speed) of the piston for the same RPM. Remember records? You know, vinyl LP's? Just as the entire record is moving at 33 RPM, the outer rim needs to travel further within the same time, thus increasing the relative speed. see Calvin and Hobbes.lol

so utilize an xb9 crank and run a larger bore to make up the displacement?

yea...but you still have a peak, somwhere around 5000rpm

so the factory rating of 103 hp @ 6800 rpm is way off...?

 

[LeFox]

so the factory rating of 103 hp @ 6800 rpm is way off...?

hp yea...not torque.

i'm a buell rider...don't care bout hp
i'm all about torque = fun factor

but if you're planning on running higher rpm with the xb12...try looking for another engine, cause the temp your engine will run at will kill it, fast!

 

[EVLTWN]

well i may have to test some limits for myself.

 

[LeFox]

you'll need to rework everything on the bike really.

the cylinders in the current engine will not be able to run at the temp your going to run.
so another cooler, other cylinders, pistons, valve springs, etc etc