2 stroke porting tips

[BNRturbos.com]

Hello all.

I am new to the site, just would like some details on porting a CR500 motor I am putting into my ATC250R. I am good with a rotary tool and have all the tools to do the job. What I need is figure out the best porting for what I am looking for. I don't want to go beyond reliability. Basically I just want to smooth things out and radius what needs to be radiused. I am sure that will free up some power.

I will be getting deep with the swap here in the next few weeks. I bought a spare frame and it will start when it gets here.

Bryan

[gravelord]

from what im told porting goes way beyond what you can do with just the tools and how much time you have on your hands... you dont have much of a option with doing it your self unless you want to hurt reliability and ruin your cylinder maybe perminantly, best to just send it out some where. most i ever did was bore out the exhaust port to a ALT50 / LT50 engine and clean it up, just my opinion though. not saying it cant be done! just saying i doubt itd be as good as sending it some where and paying 200- 300 bucks

[Billy Golightly]

I've got a ton of books on 2 stroke engine tuning. Collecting more all the time. The best one so far IMO is Gordon Jenning's 2 stroke tuners handbook. Its hard to find, but it has all the info your looking for.

[Pete]

http://www.amazon.com/Two-stroke-Tun...e=UTF8&s=books

[XTrumpX]

Jeening's book is also available in PDF format. Found this link earlier this year and it's still live:
http://edj.net/2stroke/jennings/

[88 Turbo Coupe]

After porting the head should be flow tested.

[Billy Golightly]

What part of the head are you going to flow test on a CR500 or a 250R? The water jackets?

[KASEY]

Cleaning up the ports will give you a piece of mind and thats all,,, you will not see any increase in power at all,,, its all in port timing , compression, and tuning,,, http://www.macdizzy.com/cyl_primer.htm is a great place to read ,,,

[conig]

as someone that ports its not as much rocket science as people like to make you think.

I port polaris jugs whihc are a 250r rip off in configuration shape etc. if you follow the correct steps you should have a long running engine even if you half take care of it.

chamfer the ports correctly about 30degrees. a general rule is not to excede 60% of bore width on your exhaust or the rings may not return correctly. and if there are boost ports get them till you can atleast stick your index finger in them assuming there on the intake itself, look to see if the sleave matches the jug itself and match them up. the real tricky parts are the transfers and the openings but without touching them you won;t be doing too much.

just go easy and remeber you can always open it up again, Ive ridden a cr500 and can;t say you would truly want much more then it already has. you can also stack base gaskets for some more height.