Hi you will be better running with a 360deg opening on the inlet timing than trying to run with a 155 deg duration like a std piston port engine as you will be starving the engine of fuel and air and will efect performance all round as the ex and transfer ports are set for more topend performance + the only way that you could achive a155 duration is to fill the floor of the port with weld or epoxy to achive your goal.davidblythe wrote:Have a Lined TS1 225 that has not had a boost port cut into the inlet
idea is to use mitaka TS250 pistons as they are cheap as chips for the quality on a 115mm rod with 18mm small end which I have in 58mm and 60mm strokes
will have no issues with ring pegs, then drop the timings down to stage 4 and run it on a clubman with a 30mm phbh
will not run 360deg timing on the inlet but cut the piston to run 150degs
idea is to replicate a trials bike power output and run high gearing to compensate
with all timings aiming to peak at 6500 rpm
any thoughts
the reason you have a 360 port opening is that the reeds control the inlet period (as we all know ) the higher the engine revs the longer the reeds stay open + a good pipe will help drag more fuel through the reeds ATDC when the piston is on its way back down to compress the crankcase.
I would recomend that you leave the port heights as they are but alter there width's
this will give you more torq with out gaining more revs.
I hope that this has made any sense to you
Cheers
Mick