DIY porting - 4 stroke

Joko
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10/24/2016 7:34pm
Anyone have any DIY tips for porting cylinder heads to get basic flow improvements without risking ruining the head? Maybe basic bowl blending without hitting the valve seats, excess casting removal, what shape and size carbide burr to use, what is a good inexpensive brand air gun-grinder to use?
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10/24/2016 10:00pm Edited Date/Time 10/24/2016 10:01pm
Just pull the air filter off, bounce it off the Rev limiter and dump sand down the intake. Die grinders are for chumps.

Just Google diy porting. Endless info out there.
Short version: don't remove a lot of material. Port match if necessary, smooth out your short side radii, keep your intake finish smooth, but not polished. A slightly rough intake finish helps with atomization, Polish your exhaust side.
I use a snap-on burr set 1/4 ball tipped cylinder, 1/2 ball, 1/2 to 1/4 taper are my 3 favorite carbides. From there paper rolls, then red pads, then green pads, then buffing ball with compound for the polish.
Jrewing
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10/24/2016 10:23pm
When working on the bowls near the seats concentrate. Easy to get lazy and wreck it.
The short side flow is the most important part. Just when the valve cracks open and shuts close.

I did my 15 crf450 and it makes you feel good when the weakest bike pulls slowly past on a long start uphill straight against a new yam and Ktm!

Charper732
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10/25/2016 8:43am Edited Date/Time 10/25/2016 8:44am
I'm not trying to be a dick, but if you are on vital asking those kinds of questions, you do not need to be trying to port your head. I guarantee you will ruin the velocity of the flow. ALL head work I have ever seen by new DIY'ers not using a flow bench has been drastically worse than stock ports.

If you absolutely must must fk with it, just blend the seats into the runners and stop there... majority of gains to be had are within 1 inch of the valve seat.
10/25/2016 2:54pm
For practice, go to a pull yard and pull a head off an inline 4 or 6. Gives you a bunch of ports to practice on for $50 or less. Learn to control your grinder before you dive in on a good head.
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Joshxrider
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10/25/2016 5:24pm Edited Date/Time 10/25/2016 5:25pm
You can take the (casting marks) out just smooth it up,I'd do no more than that without a professional.
Joko
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10/25/2016 7:23pm
Just sent it to Tom Morgan, decided not to mess with it.
Joshxrider
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10/26/2016 8:31am
Best idea id say,most people do more harm than good lol
10/26/2016 11:44am
Joko wrote:
Just sent it to Tom Morgan, decided not to mess with it.
Good call. I've been porting cylinders and heads for about 17 years, and still don't consider my self professional caliber. Plus if something goes wrong, it's on their dime.

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