Author Topic: benefits of porting the head on an 836 build (Read 4633 times)

75 super sport · « **on:** April 10, 2015, 01:23:13 PM »

Putting my engine back together, 836 wiseco kit, hot cam, valve springs. Didn't do anything with valves, they looked great. As I get to the head I am considering a port/ polish job. Its $450 at the local shop, so I was hoping to get some feedback on the benefits before I drop the cash to get it done. I know there's a lot of you guys with a ton of knowledge on this, so please share

thank you in advance

bwaller · « **Reply #1 on:** April 10, 2015, 01:43:26 PM »

The best money you can spend, bar none. Pick a guy with SOHC experience

Search around here. There are a million posts on the topic.

Davez134 · « **Reply #2 on:** April 10, 2015, 02:05:02 PM »

With the extra displacement and the cam, I'd say 110% port the head. That is where you will really notice gains. Speaking from very recent experience coming from an 836 bike with stock head vs this new one with ported head. Best money spent for sure.

oldhatt45 · « **Reply #3 on:** April 10, 2015, 02:34:22 PM »

75 Super Sport,

A fellow forum Member MReick (check spelling) does Heads and from all the feedback I've seen, does a heck of a job.
You might want to do a search in the forum and get his info then send him a pm to discuss your options and cost.

Charlie

SOHC4 Cafe Racer Fan · « **Reply #4 on:** April 10, 2015, 02:34:37 PM »

Best bang engine mod.

Retro Rocket · « **Reply #5 on:** April 10, 2015, 03:15:50 PM »

A stock 750 with a well ported head and cam will eat a 750 with just a 836 piston kit.... That should tell you something...

Powderman · « **Reply #6 on:** April 10, 2015, 03:26:51 PM »

I agree with Retro. The intake ports are a restriction on a stock CB750 from making appreciable power. Add the big bore and the restriction is more apparent. Porting makes a huge difference I am told.

75 super sport · « **Reply #7 on:** April 10, 2015, 03:33:58 PM »

So are we talking just taking a dremel to the intake ports?

calj737 · « **Reply #8 on:** April 10, 2015, 03:35:50 PM »

its a lot more involved and specialized than that. Hence, $450 fee.

75 super sport · « **Reply #9 on:** April 10, 2015, 03:54:12 PM »

That's what I thought. Thanks for the input guys

754 · « **Reply #10 on:** April 10, 2015, 05:23:41 PM »

I got pretty good bang for the bux with a good valve job, stock head, 836 10:1. (not talking the cheapo 836), Webers, 315cam, header pipe...and points..(maxi-dwell)... No problem running it up to 11,000 or a bit higher.
I am itching to try my ported heads, I now have..though.

Powderman · « **Reply #11 on:** April 10, 2015, 05:42:29 PM »

Quote from: 75 super sport on April 10, 2015, 03:33:58 PM

So are we talking just taking a dremel to the intake ports?

Taking a Dremel to the wrong areas without experience porting can leave you with a useless throwaway head in short order. As mentioned it is an art and a science to make it better.

754 · « **Reply #12 on:** April 10, 2015, 05:52:10 PM »

There is only about two things that are cheap to do to the 750 motors, good valvejob, and cams.. Everything else is uphill in cost..
Then there is the low compression. Cheap 836kit..I think we'll worth it for. A fairly stock motor, but I suspect the low compression won't play well with the big cams and beadwork.....just my thoughts.

Garage_guy_chris · « **Reply #13 on:** April 10, 2015, 06:21:22 PM »

I just finished a "beginner port job" on my head. This was done with a $50 set of double cut carbides and a $50 kit of cartridge rolls and arbors from summit racing. I used a small 1/4" pneumatic die grinder with a regulator sitting in my lap I constantly was adjusting the air pressure to keep the die grinder from skipping around. After that it was just alot of time i probably spent 20 hours taking my time and working slowly.

Quote from: Garage_guy_chris on March 10, 2015, 08:32:22 PM

I have a fairly nice head that was all rebuilt with stainless manley valves and mystery performance springs and retainers. Additionally Im planning on running a Kenny Harmon D grind on a Ebay Cruzin image 836cc. Problem was the ports were untouched and stock from the factory. I wanted to let Mike do his porting magic but i just cant swing the $$$ right now plus I have always wanted to try doing it myself. anyways i took my time and time it took (about 15 hours total) but here's what was done and some photos,

Basically done as per hondaman's book i wasnt looking to make any drastic changes just clean things up and make it like the best 69 head that came out of the factory.
-removed casting marks and mismatching between molding inserts,
-blended the spigots to the ports
-rounded out the bowls
-blended the ports to the valve seats (virtually no mat'l removed from seats)
-did a little work with burr's, then 80grit cartridge rolls then 120 grit cartridge rolls

this is what i ended up with, I would love to hear any input on it as its my first porting work.

Intake

Exhaust

754 · « **Reply #14 on:** April 10, 2015, 07:57:04 PM »

Electric die grinders seem to skip less....but I bet a cable handpiece is the treat..

andy750 · « **Reply #15 on:** April 11, 2015, 08:49:49 AM »

Well ported K2 head courtesy of MRiek - 810cc kit plus ported head = 71bhp

and some interesting top speeds (on a closed course naturally)

cheers
Andy

dusterdude · « **Reply #16 on:** April 11, 2015, 08:57:36 AM »

Damn thats purty

SOHC4 Cafe Racer Fan · « **Reply #17 on:** April 11, 2015, 01:40:31 PM »

Quote from: andy750 on April 11, 2015, 08:49:49 AM

Well ported K2 head courtesy of MRiek - 810cc kit plus ported head = 71bhp

and some interesting top speeds (on a closed course naturally)

cheers
Andy

Yep. THAT's what I'm talking about, Willis!

Trad · « **Reply #18 on:** April 11, 2015, 02:08:16 PM »

I too have a ported head from (Mike) Mreick. I only had the intake side of the head done with matched intake manifolds and polished combustion chambers. Pairing the with a bigger cam & high compression pistons, it should be a treat. Mike and many other have told me, without the port job, the other upgrades aren't being used to their full potential.

I've perviously installed just a bigger cam in an otherwise stock engine and noticed a nice performance increase. I can only imagine how the port work will feel.

sloephuck · « **Reply #19 on:** March 20, 2019, 01:34:42 PM »

Does anyone know of a good way to contact Mike Reik about doing head work other than sending a private message on here?

-Thanks

BomberMann650 · « **Reply #20 on:** March 20, 2019, 03:14:00 PM »

Some port jobs are done with a CNC machine. There's a european company that will shape, then dimple (think golf ball aerodynamics) the entire port from valve to manifold. Their flow bench tests show an incredible 16% increase in airflow at full valve opening. That's 16% over stock.

Porting by hand is an artform in itself. The physical skill of sculpting metal with an unforgiving tool. Need that in addition to the theoretical understanding of engine flow dynamics. Ratios of intake to exhaust sizes, tumble, swirl, bias, pressure and speed.

That knowledge is worth paying for.

Even if you decide to D.i.y. you'll pay for the job in time and materials. Studying, tooling up, securing a workspace, and developing skill (on something besides a good motorcycle head) before touching a port.

slikwilli420 · « **Reply #21 on:** March 20, 2019, 05:36:42 PM »

I'm making 80hp on 760cc, and I give most of that performance credit to the head work, done by Mike Rieck.

calj737 · « **Reply #22 on:** March 20, 2019, 07:00:31 PM »

Quote from: sloephuck on March 20, 2019, 01:34:42 PM

Does anyone know of a good way to contact Mike Reik about doing head work other than sending a private message on here?

-Thanks

Jmrieck2@gmail.com

PeWe · « **Reply #23 on:** March 21, 2019, 01:33:12 AM »

34mm in valves for K heads with std guides is available. My K6 head had F2 34mm inlet valves later replaced by Kibblewhite 5mm stem kit, 34mm In std 28mm Ex.

It cost some more with the 5mm valves. Can be an alternative if your heead need new guides and valves.
Mike make this as a stage 4 head.

My 836 delivered 81 vs 83 rwhp on dyno depending on cam. I'm sure the latter value should by bypassed by my RC295 cam profile that my butt felt as better. this with Mikuni 32mm carbs. This was with the F2 in valves.

The bike ran good in the 80's with stock carbs too. (836 and same head)

When restoring an engine, head job is needed anyway. I bet that the exhaust guides and valves are bad.
Have a look at a recently refurbished ported head is another kind of porn!

News:

Author Topic: benefits of porting the head on an 836 build (Read 4633 times)