Porting tips anyone?

[beobe99]

Well today I started porting (more like cleaning up) my intake and exhuast ports on my R project. It's a stock 250r cylinder and It's the very first time I've done this so I have acouple Qs. I'm big in the Import car scene and def. understand porting CONCEPTS but have yet to "dig" in.

Basicly what Im going for would be a "street port" (for the car guys) or a clean up/de-burring (clean up/de-burring is what I've done so far)

1. Do Pro shops use a flow bench?
2. Is there any guides, or templates out there?
3. Is it true to NOT smooth/polish the intake runner (My first thought was to make it smoooooth and polish it but my buddy was telling me leave it somewhat ruff so the air/fuel atomizes (mixes) better)
4. Any tips on continueing to do this myself.


What I did so far on exhaust side

-de-burred
-Smoothed the runner and sleeve meeting point
-Sanded with a medium grit then wet sanded
-My next step is to polish

What i did to the Intake side

-De-burred
-And started to wet sand untill my buddy called. after I talked to him I used a ruff grit paper to scrap it up... think Ill be ok? Also if the ruff grit paper is ok should i go side to side with the scrapes or with the angle of the runner?

PICS would be great if you guys have any of what you've done yourself.

Thanks fellas

Beobe

[Aceman]

Maybe try registering at the Macdizzy site. I know it costs money but I think it's only about $10 or so.

[GPracer2500]

Racelogic sells porting templates. I know zero details about it other than it exists. They call their templates "SportPort". To me, that name implies it's nothing wild.

http://www.racelogic.com/images03/racelogo.gif (http://www.racelogic.com/)

[Jason Hall]

If you don't want the power range to change, don't re-shape the ports. If you want more top end power, raise or widen the top of the exhaust port slightly.

If you just clean up the big Imperfections & open up the lower outside Intake ports (the 2 that feed the crank case directly). Then rough up the Intake walls, also the tranfer tunnels you will notice a big differance.

I have an extra ported 85-R cylinder for anyne who wants to give It a try. I won't charge anything but shipping, If you like It you can buy It If not send It back.

[beobe99]

Thanks Jason.. good info. I figured Id dig in and and give this porting a try considering used cylinders arnt all that expensive. I'll keep yours in mind.. I want low to mid range power increase...
Is that what porting you were recomending?

I checked out Race Logics site and JESUS they want $89 for the templates which I imagine is a piece of PAPER or tops a gasket of some sort..

Thanks for the info though on race logics site though. Maybe after trying this myself $89 won't seem so bad hehe!!

Thanks

[C-LEIGH RACING]

Originally posted by Aceman
Maybe try registering at the Macdizzy site. I know it costs money but I think it's only about $10 or so.

Its not a pay site any more.

beobe99
Go to Mac Dizzy & get some understanding first.
Cleaning up the cylinder casting flaws is one thing, but cutting those port windows, you realy need to know what to do or else you could end up with a piece of aluminum & an iron cylinder sleeve thats no good.
Need the proper cutting tools as well.
Neil

[Jason Hall]

When you raise or widen the exhaust port you will gain mid & top end. When I say raise the port, I don't mean the entire port. Just where the piston covers & uncovers the port. That changes the port timing. If you move the jug down (Taking material off the base of the cylinder where the base gasket goes) you can gain bottom end power. I would suggest you just clean up the rough stuff & leave the major stuff to someone who has experiance with 2 stroke porting.

As someone else said earlier, you should get some porting knowledge before just grinding on your cylinder. Learn what changes you need to make to gain power where you want It. It's real easy to ruin the jug. Sorry If I gave misleading Information.

[mineralgrey01gt]

from what ive read and heard, id take the advice from Neil (C-Leigh) straight to heart. Neil i hope you stay porting for a little while. I plan on sending an ESR 330 p/v your way for some port work :D

[beobe99]

I joined mac dizzy but my registration is still pending so I havn't been able to search the site. It only lets me see the topic headlines for now but it looks like its goingto be a good site... thanks for the link and info GPracer and C-leigh.

I spoke to the guy I got the cylinder from and he said it was allready ported SO this current cylinder I have here is usless (Its ported for top end high rev)... So Im in the market for a used unmolested cylinder (HAS to be unpainted and 87-89)

Jason - Thanks for the info and tips. I do appreciate it..

Thanks guys

Any other tip's guys? Any sources for dremel bits I should be using?

[wilkin250r]

How much have you actually researched on the subject?

There is a book called Two-Stroke Performance Tuning (http://www.amazon.com/Two-Stroke-Performance-Tuning-Bell/dp/1859606199/ref=sr_1_14/002-5838859-8557650?ie=UTF8&s=books&qid=1187575825&sr=8-14) that would be very helpful to you.

It doesn't give you specific tips and tricks, where to cut, which bits and tools to use, ect ect. It's not a walk-through. But it WILL give you almost all aspects to consider when porting. The size and power delivery are obvious considerations, but there are minimum wall widths for proper sealing, ring gap locations, and port angles to consider, among others. This book explains those aspects and what to look for.

With this book, you might feel comfortable making small changes to your port shape, and testing the results.

This book alone obviously won't make you an expert, but it gives you enough information to start your first experiments with relative success, and from there, you learn more.

[regg187]

I used to ride with a group of guys that were all extremely knowledge able with 2 stroke non-pv porting. the basic concenses was for a good "clean up" job for the 250r was raise the exhaust no more than 1mm and clean up the transfers that feed the crank and any casting flaws in the others. changin port shape(wideing) and changing transfer port timing (height) can leave you with a paperweight with out alot of 2 stroke enginetheory and alot of flow calculations. just my 2 cents:)

[machwon]

My suggestion is to only raise the exhaust port on a 250 R cylinder, regardless of the tools you have. Width is important also. Anyone who's worth a hill of beans know this, Regg187 is right on! Impressions of porting can really vary, clean ups are in the eye of the beholder. If you plan on doing your own porting, look at every cylinder you can, keep good notes, and don't be afraid to try someone elses work that does good. The :devil: 's in the details.