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Author Topic: Porting head.  (Read 3768 times)

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Offline The French Dude

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Porting head.
« on: July 29, 2017, 06:41:53 AM »
Hi Guys.
I am curious about porting head. Looked around on the internets had some basics informations but nothing on cb750 heads.
So my question could be pretty innocent but... Is there a "how to" cb750 related?

Thank you.
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77' cb750k

Offline innovativems

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Re: Porting head.
« Reply #1 on: July 29, 2017, 08:13:16 AM »
I would send it to Jmr. He's a master on the cb's


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Offline mj1176

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Re: Porting head.
« Reply #2 on: July 29, 2017, 08:14:32 AM »
Not to be rude, but if you need a How To for porting you should probably try to find someone who you can pay to do it that will let you watch or something.
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Offline Stev-o

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Re: Porting head.
« Reply #3 on: July 29, 2017, 08:43:49 AM »
Hey French Dude....have a look at this thread, let us know how it goes.

http://forums.sohc4.net/index.php?topic=132814.0
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'74 "Big Bang" Honda 750K [836].....'76 Honda 550F.....K3 Park Racer!......and a Bomber!............plus plus plus.........

Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Porting head.
« Reply #4 on: July 29, 2017, 09:09:01 AM »
Perhaps get a spare one to practice on? There are many ported heads on here and lots on information. However it's unfortunate we don't have a direct search function.
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As of today 3/13/2012 my original owner 75 CB750F has made it through 3 wives, er EX-wives. Free at last.  ;-)

Offline seanbarney41

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Re: Porting head.
« Reply #5 on: July 29, 2017, 10:05:26 AM »
Hondaman's book has good basic instructions.
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If it works good, it looks good...

Offline The French Dude

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Re: Porting head.
« Reply #6 on: July 30, 2017, 07:33:02 AM »
Quote from: innovativems on July 29, 2017, 08:13:16 AM
I would send it to Jmr. He's a master on the cb's


Sent from my iPhone using Tapatalk

Can be an option. But really want to understand the process and how to make it in a certain manner.
Where can I find them?
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77' cb750k

Offline The French Dude

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Re: Porting head.
« Reply #7 on: July 30, 2017, 07:33:53 AM »
Quote from: mj1176 on July 29, 2017, 08:14:32 AM
Not to be rude, but if you need a How To for porting you should probably try to find someone who you can pay to do it that will let you watch or something.

Thx but I want to understand by myself ;) sort of life school !
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77' cb750k

Offline The French Dude

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Re: Porting head.
« Reply #8 on: July 30, 2017, 07:34:20 AM »
Quote from: Stev-o on July 29, 2017, 08:43:49 AM
Hey French Dude....have a look at this thread, let us know how it goes.

http://forums.sohc4.net/index.php?topic=132814.0

Thanks!
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77' cb750k

Offline Killer Canary

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Re: Porting head.
« Reply #9 on: July 30, 2017, 08:28:04 AM »
Quote from: mj1176 on July 29, 2017, 08:14:32 AM
Not to be rude, but if you need a How To for porting you should probably try to find someone who you can pay to do it that will let you watch or something.
So this guy "who you can pay to do that" popped out of the womb knowing how to port heads?
Shove your poor advice up your ass.
Have a nice day.
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If it's worth doing at all it's worth over-doing.
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Offline BomberMann650

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Re: Porting head.
« Reply #10 on: July 30, 2017, 09:04:47 AM »
Gotta be good with a rotary tool first!
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Offline jgger

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Re: Porting head.
« Reply #11 on: July 30, 2017, 09:59:01 AM »
Quote from: Stev-o on July 29, 2017, 08:43:49 AM
Hey French Dude....have a look at this thread, let us know how it goes.

http://forums.sohc4.net/index.php?topic=132814.0

Very interesting read, it would be better if Photo f@cket hadn't locked up the pics.
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Offline Killer Canary

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Re: Porting head.
« Reply #12 on: July 30, 2017, 11:37:58 AM »
That was uncalled for.
Sorry.
I'll piss off til I'm in a better mood. ;D
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If it's worth doing at all it's worth over-doing.
Honda MT250, CB400F, CB450K, CB550, GL500, CBR929
Kawi GPz900, H1

Offline preston

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Re: Porting head.
« Reply #13 on: July 30, 2017, 01:56:58 PM »
 Just finished my 750 head with a mild porting using an air die grinder and different
grit cartaridge rolls ( a dermal tool will work but the tooling sizes available are too small
for such a large port). I work out the casting flaws and smooth out any transitions around
the valve seats and guides ( I did not have the guides removed on this head so I did as
best as possible in the confined space.
 Took about 10 hours, free time well spent for FREE HORSEPOWER.  ;)
 Here are a few shots of the finished job.
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Offline madmtnmotors

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Re: Porting head.
« Reply #14 on: July 30, 2017, 02:25:50 PM »
Quote from: Killer Canary on July 30, 2017, 11:37:58 AM
That was uncalled for.
Sorry.
I'll piss off til I'm in a better mood. ;D

I was hoping you were having a momentary lapse!  8)


As for porting heads, one of the most important tools for doing it properly (IMHO) is a flowbench. Mild port work limited to just some smoothing of the ports should not create too much of an imbalance. The more material that is removed, and more reshaping that is done, makes the flowbench that much more important. Do a little work to each port at a time trying to keep them even.
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Offline The French Dude

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Re: Porting head.
« Reply #15 on: July 31, 2017, 07:29:52 PM »
Quote from: preston on July 30, 2017, 01:56:58 PM
Just finished my 750 head with a mild porting using an air die grinder and different
grit cartaridge rolls ( a dermal tool will work but the tooling sizes available are too small
for such a large port). I work out the casting flaws and smooth out any transitions around
the valve seats and guides ( I did not have the guides removed on this head so I did as
best as possible in the confined space.
 Took about 10 hours, free time well spent for FREE HORSEPOWER.  ;)
 Here are a few shots of the finished job.

Nice job!!!
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77' cb750k
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