hand port and polish a yz250f head

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4/17/2018 7:42 PM
Edited Date/Time: 4/17/2018 7:43 PM

Has anyone had any experience hand porting and polishing a 4 stroke head?

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4/17/2018 8:06 PM

Yes

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4/17/2018 8:56 PM
Edited Date/Time: 4/17/2018 8:56 PM

Without a flow bench u are only guessing and could be doing more bad than good. Unless u are only cleaning up casting flaws

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4/17/2018 9:01 PM

ktm-5 wrote:

Without a flow bench u are only guessing and could be doing more bad than good. Unless u are only cleaning up casting flaws

I guess that was what I am looking for, knowing how much and where material should be removed besides just guessing.

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4/18/2018 4:17 AM
Edited Date/Time: 4/18/2018 4:18 AM

ktm-5 wrote:

Without a flow bench u are only guessing and could be doing more bad than good. Unless u are only cleaning up casting flaws

alex465 wrote:

I guess that was what I am looking for, knowing how much and where material should be removed besides just guessing.

Yup need someone with a flow bench, when I bought my modded head for my 250f it was pretty crazy to see what was done to make it better and it was done using a flow bench so he could prove it worked better. If you want your head done correctly contact Ron Hamp

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4/18/2018 7:19 AM

ktm-5 wrote:

Without a flow bench u are only guessing and could be doing more bad than good. Unless u are only cleaning up casting flaws

alex465 wrote:

I guess that was what I am looking for, knowing how much and where material should be removed besides just guessing.

I don't think anyone that invests in a flow bench, dyno, porting tools, fuel and all that time is going to just give up their trade secrets. I wouldn't but if you google long enough you might find some general info on principles of porting a 4 stroke head.

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The older I get, the faster I was.

4/18/2018 11:53 AM

ktm-5 wrote:

Yup need someone with a flow bench, when I bought my modded head for my 250f it was pretty crazy to see what was done to make it better and it was done using a flow bench so he could prove it worked better. If you want your head done correctly contact Ron Hamp

A flow bench is only a small piece to the puzzle. A head that flows the highest number wont necessarily make the most power or be the fastest on the track.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Specialized Fuse Comp 29.

Sold: 2016 YZ250F, 2012 CRF250R

4/18/2018 12:32 PM

alex465 wrote:

I guess that was what I am looking for, knowing how much and where material should be removed besides just guessing.

ktm-5 wrote:

Yup need someone with a flow bench, when I bought my modded head for my 250f it was pretty crazy to see what was done to make it better and it was done using a flow bench so he could prove it worked better. If you want your head done correctly contact Ron Hamp

c0ncEpT wrote:

A flow bench is only a small piece to the puzzle. A head that flows the highest number wont necessarily make the most power or be the fastest on the track.

Actually I'd say it's more than a small piece of the puzzle. I'll agree dyno numbers don't equivalent to fastest on the track but airflow is where hp is made so I'm curious where you'd say hp is made?

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4/18/2018 1:02 PM
Edited Date/Time: 4/18/2018 1:06 PM

ktm-5 wrote:

Actually I'd say it's more than a small piece of the puzzle. I'll agree dyno numbers don't equivalent to fastest on the track but airflow is where hp is made so I'm curious where you'd say hp is made?

Airflow and air speed are 2 different things.

Call Ron and ask him if he's ever added epoxy to the floor of a port, hurt CFM but gained power. I'm willing to bet we could all learn something.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Specialized Fuse Comp 29.

Sold: 2016 YZ250F, 2012 CRF250R

4/18/2018 1:10 PM

c0ncEpT wrote:

A flow bench is only a small piece to the puzzle. A head that flows the highest number wont necessarily make the most power or be the fastest on the track.

ktm-5 wrote:

Actually I'd say it's more than a small piece of the puzzle. I'll agree dyno numbers don't equivalent to fastest on the track but airflow is where hp is made so I'm curious where you'd say hp is made?

c0ncEpT wrote:

Airflow and air speed are 2 different things.

Call Ron and ask him if he's ever added epoxy to the floor of a port, hurt CFM but gained power. I'm willing to bet we could all learn something.

No need to call Ron, he is the one who built my head and I've spent a lot of time with him. I won't give out what was done to my head exactly but here is the ad he had when he was selling my head and "it wouldn't have been don't without the flow bench", his words not mine.Photo

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