port matching questions!

[rami]

Hello everyone!

So as it turns out, I might be the one to do the porting on my crankcases, first of all, I would like to ask, would the grinder I attached be able to do the job?





If it is, then I would be interested what type of carbide burrs to use? What shape, what type of cut? We are talking about derbi euro 3 engine (d50b), if I had to guess, I would say it is some type of aluminium alloy, so maybe not full aluminium. Is it worth buying "more quality" carbide burrs? (1 piece of carbide burr in my country costs around the same as a 10 piece carbide burr set from aliexpress.)
Basically any advice is greatly appreciated, maybe some mistakes you did when you did it for the first time.

Thank you, have a nice day!

[oldgeek]

It is cast aluminum. A burr like these is what you want to use, large flutes that do not clog so easily. I do not have any experience with those motors, so maybe someone else can help with that.

[jackrides]

A bar of Ivory soap to lube the burr will reduce clogging. Machinists dye or a black Magic Marker applied to the area will allow you to scribe (mark) lines where the limit of your cut will guide you. Figure the angle of a burr by being having your well lighted workstation comfortably set up with cylinder solidly in place. Now unplug the grinder and practice the grinds you want to make. Cut some index cards to the angle that works, and you'll be ready.This isn't something you need to put a # of degrees on, just be as close as you can. Practice Shallow smooth cuts. Any corner with more than a right angle of material in contact with the burr is at risk of chattering, meaning an uncontrolled shaking of the burr. Obviously have a firm grip on the tool and be prepared to pull the tool back quickly. Your patient care will be rewarded! Smooth is Key! Polish exhaust ports. Do not polish intake, but smooth it. Transfers should be smooth. Rounded transfer port entrances are better than sharp edges. (The air flow is subsonic.) Keep the Forum posted please.

[rami]

Thank you for your answers and advices! I will use them. Fortunately, I'm a pretty patient guy, especially when it comes to something I like to do. I will post the results!

[rami]

Finally, I can come up with the results people probably dont even remember. I tried my best, the porting didn't turn out to be perfect, but for a first timer its pretty okay. Its a bit grumpy where I couldn't fit in with my dremel so I was losing angle in order to mill it out, also had a lot of other problems with this dremel, next time im going to do this I will invest into a quality kit.

[jackrides]

Dremel has a flex-cable attachment with a smaller bit holder that fits a lot of thir models.