Port timings for KRR150 (maybe KR150 too?)

[FzerozeroT]

sub exhaust:27.5mm
centre exhaust :30mm
tranfer :42mm
use HMF exhaust muffler


I just got sent these from a guy in singapore, they are for the later model KRR150 but if the earlier wire wheel bike also uses the same engine they should be sweet too.

[geoffm]

sub exhaust:27.5mm
centre exhaust :30mm
tranfer :42mm
use HMF exhaust muffler


I just got sent these from a guy in singapore, they are for the later model KRR150 but if the earlier wire wheel bike also uses the same engine they should be sweet too.

Now you need the port width and corner radius, and then you can work out the port time-area and duration (along with the stroke and bore). This can be used to optimise the porting, and design expansion chambers. The port height by itself isn't particuarly useful. For more info, see Prof GP Blairs excellent books. AG Bell's book isn't bad either.
Geoff

[FzerozeroT]

I assume that he just meant to stretch the prts downwards and keep original width and radius? They tune a LOT of these in singapore/thailand so I'd assume he knows what he's doing.