Trying to get some cylinders ready over the winter. Looking for some imput. I opened up the intake transfer and eyebrow, exhaust transfer opened up at the top and blended in. Ring nub removed in the intake only. Exhaust raised only. Squish at 13, In at 157, Ex at 182. Does the intake and exhaust port have to be opened up like a zen?

Sounds like you have made most of the internal mods already. As too the intake ports width, if setting up for an RPM application you can add width and gain some top end rpm at expense of a bit of torque.
If needing the torque leave the width alone. 157* duration will work quite well.

Exhaust at 182 or so is right in the sweet spot and hopefully you kept an arched roof profile ?
The EX port can use some more width up on the top edge tho try and keep the outward sloping angle of the sides leaving floor width stock as well.

You should have a great runner !!

Yes Scott the work is already done. I did the best i could with the arched roof on the exhaust, Its a little flat in the center, I hope it does not hurt the power band to much. I will go back in and open it up in the corners like you said. I thought the exhaust and intake port looked small compared to a mod zen. Due you think i can reach the high seventeens with this set up? Thanks mick

With the timing specs you are using, and if your savvy on getting the pipe length short enough for power in that range and prop accordingly you will be high 17's mid 18's no problem IMO

If the motors work the way they should then i know my NFS pipes will do the rest. When is your mod review on the evo due out?

Honestly, with the stock EVO's running so well and all that has been covered within other "How Too" modify articles ... all one really need do is connect the dots
Which from what you have already done internally .... you already did

Hi Scott,
Thanks for all the great info, I have a evo rear ex that I am about to have a go at modifying, I Was wondering if I should shape the ex and intake ports as you would a side port engine?
Thanks
Damian

You can do some widening, tho DON'T go after the rectangular shape of the original cylinders intake & exhaust ports ... keep them an elliptical oval if you do widen

Thanks Scott,
I will start choppin, would I be right in thinking that it would not be a good idea to lighten the piston on the rear exhaust?, have already seen some wear on the skirts in line with the transfer bridges after only about 1 1/2 hrs of running.

Would think the way RCMK casts there pistons, getting a weight reduction would not be worth the effort.
Yup ... we all figured wear would be greater on the RX engines piston with open transfers ... When wear gets excessive or engine starts rattling ... replace it.