I checked my port timing on my 535 10mil motor. Looks like I got 198 degrees of exhust port open time and 127 degrees of transfer port open time. Anyone get similar results? I is a stock, unported cyl.
Thanks!

no one has done port timing on a cheetah cyl

that sounds like as cast( they are usually a bit higher on transfer numbers but trinity sets the cheetahs) i would raise the transfers to 128-130 and get some better torque. if the exhaust is higher in time area in the blowdown phase the engine will be peaky and a raise in the transfer TA will balance it out and broaden the curve

Thanks Tim, you have a PM

There are guys out there who make a living porting. Your best results are gonna be paying for a port job and copying it if you can. As a guy who makes a living doing it its not easy nor would I be excited about telling someone else how to do it..... Properly... IMO Pay rdz or someone to do it and then degree it if you want numbers.. Like everyone else had to do

talk to as many professionals as you can. read as many books as you can. do alittle r&d of your own. its best to have knowledge from all angles and not just one source

I agree,

some things you wont be able to copy and the timings are just one part of the layout, and In the post he didnt mention the turbo, that changes everything.

Alls I know is that all the best of the best at porting have made a stack of junk cylinders in the back of the shop before hittin the nail on the head. Porting is an art... You can either feel what your trying to do or not.

the old timers most likely learned by hands on. the new up and comers are probly relying heavily on computers to figure most of the calculations, which is fine and dandy but computers are only as good as the programmer and his information sources. i doubt theres a 2stroke program in the world that doesnt have flaws in it somewhere. without atleast some hands on knowledge its going to diffucult to identify computer miscalculations

I agree totally on this, I have some of the best software out there and it is really nice for it to crunch the math for you but it cant build for you .

I didnt have these programs 20 years ago when I was buildin Hybrids, so there were a bunch of notebooks and erasers lol. I have a pile of notes in my head on what not to do! lol I was going through a cabinet a few weeks ago and found an old notebook that was about 15 years old and man it was like, how did i get by without Rhino* on dome profiles or enginemod2t on transfer tunnel volumes and exhaust blow-down to transfer window STA , or thanx to Calvin, Vellum on total engine drawings and the ability to group things in and out of a whole assembly, before software these things were just happened across and mocked up dozens of times and you did what worked, and had a massive pile of rods, pistons and cases just for mockup, problem here is this industry had a massive growth spurt in the last 7 or 8 years and that empirical data that worked on one setup wouldn't do for the dozen different setups now available, I don't port a cub like a stocker or a dm like a cub or a cougar or a scimitar and so on , they all have there separate layouts and each one of them can be built with different major differences,and you have to recognize the differences, a 132 rod,72 stroke dm with a 3+ mm domed piston will have a different need on a dome profile than a 125 rod engine with a flat top, not talking about obvious measurements but the changes the different measurement cause, not to mention volumes in the porting because of velocities.and lets not forget the pipe, lol its not there on vacation, lol I can nit pic any layout I see even my own sometimes but what it boils down to is efficiency on a given setup, that comes with experience, its been a while but i have had to mill out the side of a cylinder once or twice to weld up a water jacket above a transfer lol , so I agree with rob, there is a bunch of trial and error, but today there are guys who will help you

Dan I need this steps measurement on your dome

Thanks tim for the great service