Topic: CB550 home porting attempt

[Scott S]

 We also clearanced the head for the CB650cam. The intake side was fine, but it needed clearancing all the way across on the exhaust side. I didn't have my feeler guages with me, but we just matched the clearance from the intake side.

[Scott S]

Looks Great! Did you end up making a flow bench?

 No, but we did take it over to our local head porting guru. He checked it out and gave his approval, along with a few tips and some nice bits and stones that really helped get the last little bit done.
 He also checked the head for straightness and we couldn't even get a .002" feeler guage under the straight edge. I'd say that's pretty true!
 I had thoughts of decking it slightly for a small CR bump, but it's in such good shape I just left it alone. This was a really nice head to start with.

 We did polish all the valves and lapped them in today (this pics is pre-lapping).


 Gave a a mild cleaning and sprayed it down with WD40 to prevent flash rust in the seats, stem, valves, etc.
 Next up: A REAL cleaning and re-assembly.

[Scott S]

 Oh, and I didn't get any pics, but we polished up the intake manifolds a bit more, too. They're a little more "finished" than in the previous pic on page one.

[Scott S]

I found that a deep pocket (I took out 2-3mm) below the valve guide shown in your first pic made a big difference.  I blended that into the rest of the port and opened up the port on either side of the valve guide.  Camelman

 Can you elaborate on this? Any pics?

[Gearheadgreg]

Nice work and pictures, my Son has worked with me full time in the trades for last 7 years, Yes we do but heads, But he is my right arm. Porting will really open up your upper RPM's, If you have a local machine shop have them do a 3 Angle back cut on your valves before you install them, it will  help flow more air with your port work. http://www.v8wizard.com/3-angle-valves.php

[faux fiddy]

I cleaned up my 350f ports, nothing drastic, no 3mm digs. I just smoothed out the casting marks, I used no power tools. 

These files were handy, heat them up and bend them over.

[MRieck]

Nice work and pictures, my Son has worked with me full time in the trades for last 7 years, Yes we do but heads, But he is my right arm. Porting will really open up your upper RPM's, If you have a local machine shop have them do a 3 Angle back cut on your valves before you install them, it will  help flow more air with your port work. http://www.v8wizard.com/3-angle-valves.php

The backcut on the valve is 1 angle in general. That article was talking about the cuts on the seat.

[Gearheadgreg]

Nice work and pictures, my Son has worked with me full time in the trades for last 7 years, Yes we do but heads, But he is my right arm. Porting will really open up your upper RPM's, If you have a local machine shop have them do a 3 Angle back cut on your valves before you install them, it will  help flow more air with your port work. http://www.v8wizard.com/3-angle-valves.php

The backcut on the valve is 1 angle in general. That article was talking about the cuts on the seat.

Also gave a good description and picture of back-cut valve, "We were all hoping you would give us some pointers here"? 

[Scott S]

 Still wondering about the size, shape and location of the "pocket" or "dish"....

[MRieck]

Still wondering about the size, shape and location of the "pocket" or "dish"....

The pocket would be the section right behind the guide. You want to increase the radius to help charge past the seat. To little "curve" has charge bouncing off the back of the bowl roof. You cannot "bend" charge...it wants to go straight and that is it. You can try to "guide" it. Porting and flow are most often "line of sight". You see things straight when you look down a port....that is the way charge sees it too.
.

[Scott S]

 By "back of the guide", do you mean coming in from the manifold side? Like I was looking into the port, from the direction in your avatar pic, it would be at the 12 o'clock position?

 Or am I on the combustion chamber side where the guide itself sticks into the port? That would be just below the dark circle around the guide in this pic, at ~ 6 o'clock.

[MRieck]

By "back of the guide", do you mean coming in from the manifold side? Like I was looking into the port, from the direction in your avatar pic?

Yes

[Scott S]

 Oops, editing my post when you replied. So, at the "roof" of the port, so to speak....as looking at your avatar pic.

[MRieck]

Oops, editing my post when you replied. So, at the "roof" of the port, so to speak....as looking at your avatar pic.

The "roof" or top of the port...they are synonomous. Where it curves to lead into the seat....you can deepen and enlarge that area. You did alright as it is....it is difficult to do without larger, 1/4" shank burrs.

[Scott S]

You did alright as it is....

 I will GLADLY take that compliment from you, Mike.

[seanbarney41]

Hi Scott...I was just looking back into this thread and was wondering if you had any butt dyno charts on how this came out

[Bailgang]

I'm not crazy about doing any serious reshaping of the ports on a multi cyl engine without the use of a flow bench but a flow bench isn't the kind of equipment you're going to find in every garage either in fact I know of only 1 speed shop around here that has 1. Don't take that the wrong way Scott, it's obvious at least to me that you were very patient and methodical and it looks good, I admire your nerve to take on the challenge.

On the other hand my brother had a Harley XLCR and found out the PO had literally butchered and I do mean absolutely butchered the ports on it's heads with a die grinder. My brother had to toss the heads and get new ones.

[dave500]

if you want to be fussy use new screws for the vacuum ports which are slightly longer,then buzz them inside to flush perfectly,then mark them on their head with one punch mark for intake one,two punch marks for two and so on,use stainless with copper washers.

[Scott S]

Hi Scott...I was just looking back into this thread and was wondering if you had any butt dyno charts on how this came out

 From idle to about 5,000 rpm, I don't think it feels much different than any other 550 I've ridden. Nice idle, pulls good at low RPM, etc. But somewhere just above 5K, it's like someone flipped a switch. A noticeable surge in power and pulls hard to redline. Driveability is very good and gas mileage is in the mid 40's.

[seanbarney41]

...and tell us a little about any other mods that you may have done, carbs?, cam?, displacement? sprockets?, if you would be so kind...

[Scott S]

 Ported and polished the head as seen in this thread, match ported and smoothed the manifolds, 105 mains in the carbs (I'm trying to remember if I raised the needle one clip....seems like I did but I'm not 100% sure anymore), 1.00mm overbore for 563cc,  Jardine 4-1, CB650 cam, Pamco ignition, new coils/wires/caps/plugs, Uni filter in stock air box.

 Sprockets are stock, Progressive shocks, dual discs, etc., etc.

[seanbarney41]

sounds like the extra work payed off

[WarwickE36]

Just finishing up doing this with my cb350.  Lookin good seanbarney... It sucks trying to get the flap wheel into the tight spots,  I am going to get some crossbuff bits to smooth it 100%

Ground down


Almost done


Interested to see your results