Do it yourself porting/polishing?

[stocktires]

I've got a crf motor that I may rip apart. Has anyone done there own porting and polishing? I don't want to do anything serious which is why i may do it myself rather than pay like $300. I just mainly want to smoothen the ports and remove casting flaws, has anyone done this to their own motor? What all is needed and how do i go about it? I have a nice dremel tool.

[xxnightraven73x]

ive done it on a few motors but it really doesnt do all that much.unless you get it done at the machine shop where it gets flow bench tested and all.but you can do it if you wanted too.ive done it with a dremel and deburring attachment and some sanding drums i did my header pipes that way

[boricua]

good luck!

get a few of those sanding drums, youll prolly go through a few.
what you should be aiming for is a satin finish, not polished smooth. not sure how bad the casting is but without removing material, you may not notice much of a gain. porting can be difficult not to mention is usually a one way deal. if you make a mistake its expensive to have material welded back on to the head. and then you have to start all over.
the process usually starts with a cutting bit to roughly remove material. with the rough, new shape in the port, you start sanding the cut marks out. begining with a coarse grit and finishing with finer grit. i dont recall what grit to finish with. i would say not less than 80-100 grit.

again, good luck. :macho

[JOEX]

Grinding and polishing may be easy to do but knowing where and how much to grind is why the pros get the $$;)

[2muchquad]

But conversely...theres only one way to learn.Its not exactly rocket science even though some things should be left for pros.If your like me you'll want to find out for yourself though.Do lots of research online and just start by taking a lil bit' here and there until you learn whats going on.Too much and you'll wind up with a $400 paperweight.;)

[stocktires]

I have no plans of porting, just a slight polish and removing of casting flaws. I doubt it'll make much of a difference, but some.
I'm thinking a 12.5:1 compression, with a stage 1 cam, and polished head should make my crf rip.

[1fst400]

I doubt it will make a noticible diffrence. But as long as you take it easy it wont hurt anything. while your at it re-seat the valves and install new seals.

[firefighterjosh]

I did it to my banshee. I mainly just polished it and were the jugs wer put together had little tabs and I grinede them off. I notice a little diffrence but the main thing was throttle reponse

[boricua]

2 stroke porting is much different though...

my understanding is you want high velocity and high volume throughout the rpm range....obviously, it doesnt work that easy. a comprise must be made. more at the bottom, mid or top end....
too big a port and velocity will be slow, torque will be low, sluggish engine. to small and volume would be low, good bottom with little mid and nearly no top end.....

research. everybody has there own idea of what should be done and what works better....research.

[firefighterjosh]

We also did are own polishing work to a old NIssan:) Didn't notice a darn thing lol. We also tried to port and polish a razz. increased top end but lost bottom end horibly. Next I am going to try a Briggs and Straton. Not gonna take much off though. I took way too much off the razz

[00tn300ex]

one of my buddies i ride streetbikes with done something called velocity porting to his cbr600rr.He said that he actually added material and changed the shape of the ports.He is a great mechanic and his bike is extremely fast.He has it turning almost 17000 rpms

[firefighterjosh]

Originally posted by 00tn300ex
one of my buddies i ride streetbikes with done something called velocity porting to his cbr600rr.He said that he actually added material and changed the shape of the ports.He is a great mechanic and his bike is extremely fast.He has it turning almost 17000 rpms

I thought a stock bike could turn 17,000 RPMS??? Or am I thinking 14,000?

[00tn300ex]

i belive it is 14000,plus his is the first year model,which had a lower redline.Ive been meaning to get in touch with him and get some more info about the velocity porting just havent seen him in awhile,he was racing pro and won a few races with the 600.

[firefighterjosh]

I don't know much about bikes, so I wasn't sure.

[00tn300ex]

yeah the fuel injection and all that kinda stuff gets complicated for me.Thats why i get him to work on mine:D