Topic: CB550 Performance Mods, A La HondaMan...

[paulages]

my first car was a 1970-something civic cvcc (if i remember right). it did look quite confusing under the hood, but got great gas mileage, and had some get-up-and-go!

anyway, the passage i posted was only relevant to the extent that engineers figured out at some point that the shape of the port would affect the swirl pattern. that particular patent was referencing a port shape that became most common with dual-valve intakes (and is used today in most superbikes).

[HondaMan]

my first car was a 1970-something civic cvcc (if i remember right). it dod look quite confusing under the hood, but got great gas mileage, and had some get-up-and-go!

anyway, the passage i posted was only relevant to the extent that engineers figured out at some point that the shape of the port would affect the swirl pattern. that particular patent was referencing a port shape that became most common with dual-valve intakes (and is used today in most superbikes).

Yeah, it takes some valve configuration to take advantage of special port shapes like that. I just wish I had the facilities to cast my own heads.   

[Jonesy]

Were those similar to the old Gordini racing heads that had a "preignition" chamber above the main combustion chamber? The sparkplug threads into a small chamber that connects to the combustion chamber via 2 passages. A friend has an old Renault Matra with a Gordini motor and discovered this.

[HondaMan]

Were those similar to the old Gordini racing heads that had a "preignition" chamber above the main combustion chamber? The sparkplug threads into a small chamber that connects to the combustion chamber via 2 passages. A friend has an old Renault Matra with a Gordini motor and discovered this.

Yep, sounds very similar.

[ludite13]

So Jonsey,
  How does the 550 run now?

-James

[Jonesy]

It runs really good. After looking at the cross-sectional head photos from the other 550 performance mod thread, I can see I probably could have gone farther, but now I have some experience. The bike still starts and idles nicely, and upon acceleration the engine really seems to start pulling around 5,000-5,500 RPM. Seems more peppy in this range.

Mind you, all of this is with a completely stock engine configuration. I plan on looking into the other modifications HondaMan lists. I got another advancer and will try the spring/advance mods, and keep checking the jetting. I am also looking for a K&N filter. I can't do much with the sprocket ratios as there is not nearly the aftermarket offering for the 550 as there is the 750...(short of having sprockets custom-made.) I may try dropping a tooth on the front, as opposed to adding teeth on the rear.

I am happy with the results, and my wife liked the way it rode as well. I'm trying to convince her to let the engine wind up more. I asked her if she noticed a difference above 5 grand. She said, "I didn't get the revs up that high." I replied, "Then you're not really riding it!"

[mgmuellner]

Did you by chance dyno it prior to the change?  I'd love to see more hard data than seat of the pants.

[Jonesy]

Nope. Didn't dyno it because I didn't originally plan on doing the mods when I took it apart, just wanted to seal up some oil leaks. But, after I got it apart, a buddy urged me to do it, since I already had it apart far enough...

I mainly posted this as Mark had posted some ways to improve the performance, and as far as I know, I've been the first to take this info and do something with it, so I wanted to share my experience with the rest of they group if they were considering any of these changes.


I think this had more to do with the "feel" of the bike more than anything: http://www.sohc4.us/forums/index.php?topic=7401.msg67251#msg67251

[tsflstb]

Nice work.  I've always thought just cleaning up those castings would help.


If you're still looking for sprockets, I bought mine here:

http://www.sprocketspecialists.com/ProductSearch2.aspx

I guess they're made to order.  They list a 74-78 CB550 in there...aluminum rear sprocket with 33-71(!) teeth.  I think they just carry the stock number of teeth in steel.  I like the aluminum myself and haven't noticed it wearing any faster than the stock piece.  If I remember, the last one I bought was around $30 a few years ago for a 40 tooth aluminum.  Seemed cheap enough.  They do good work and are amazingly fast.  If I were you, I'd slap the 71 toother on there and see if your wife notices...

[Jonesy]

Great Website!!! Thanks!

Can we add this link to the FAQ?

[HondaMan]

Terrific post, Jonesy!
Beautiful machine work, too. 

[FunJimmy]

Jonesy

It's been a month since your last update on this topic.
Inquiring minds at needing to know, just how much difference did it make?
I'm looking at doing this as well, and it surely looks like a lot of work.
Would you do it all over again?
What other mods would you recommend to enhance the head work?

Great post! Thanks
Jimmy

[HondaMan]

Jonesy

It's been a month since your last update on this topic.
Inquiring minds at needing to know, just how much difference did it make?
I'm looking at doing this as well, and it surely looks like a lot of work.
Would you do it all over again?
What other mods would you recommend to enhance the head work?

Great post! Thanks
Jimmy

After these head mods, like Jonesy has done, a better-breathing cam is a real good "next step".

[ieism]

If it ain't broken, fix it! 

This is interesting to read about, but I doubt i'll ever have the guts to try it on my 550. What would it cost to have something like this done by a professional? How many hours would it take a skilled person?

[HondaMan]

If it ain't broken, fix it! 

This is interesting to read about, but I doubt i'll ever have the guts to try it on my 550. What would it cost to have something like this done by a professional? How many hours would it take a skilled person?

In 1972, I would get about $250 (plus parts) for this work: today it's about twice that.

[Jonesy]

Well, with all the posts regarding the "sharing" the Canadians have done with the cold and snow, we haven't been able to ride the bike a whole lot, being in Michigan. But, my wife and I both notice a difference at higher RPM's (around 5,000 it comes on strong). I can also tell the bike is breathing better as the existing jetting now appears a bit on the lean side. The plugs (NipponDenso X22's, the equivalent to the NGK D7EA and feature the U-groove ground electrode) are almost white, with a bit of grayish deposits. Also, the header pipes at the mounting collars are starting to turn a goldish color. I need to go in and raise the needles a notch and maybe also up the main by 5.

I looked into a cam for it. Webcams offers a 550 performance cam, but it runs around $350 and you have to trade in your old cam as a core (a bit pricey for me right now). I haven't yet played with the advancer mod. Keep in mind aside from the head work, all else on the bike is still stock.

If I had to do it over again, I would have had the bike dyno'ed to be able to quantify the difference, but as I said before I didn't intend to do the work until after I got it apart. The main thing was since I had never attempted porting work, I would be happy as long as it ran the same or better- just as long as I didn't decrease the performance.

I would do it again. I enjoyed the learning experience. The first port was the hardest, as you are feeling out the process. Once you know what has to be done, which tools work the best for it, where to find the tools you need, etc, it goes much faster. You are looking at 2 weeks worth of work, consisting of a few hours in the evenings after the "day job". Plus, I'd do a bit of work and send pics to Mark so he could check my progress, so this extended the project a bit as well. I'm not sure how long it would take a pro to do it...

[ludite13]

Sounds good.  I finally stripped my 550 parts bike and have the motor on the floor.  I can now work over that head and swap it out for the one on the running bike.  I guess that will extend the project as I won't have the bike disabled!  

-James

[DarkRider]

Bringing this post back from the dead i know but i must say this is a very well written article man! Def gonna be using this article as a guide with my own 550. The upside with many bikes is this..i can go and do more extensive mods to the CB and wind up with a wicked lil bike after.

[BlindJoe]

Hey Jonesy,

             Was wondering if you tried messing around with the jetting/needle position at all? I followed your great right up and did this on my 77 550 k recently, except I did more work on the exhaust ports than the intake. I've had similar experience with it coming on strong around 5500 rpms.

How is your acceleration in the lower rpms? Compared to my friends cm400 mine seems to be a bit sluggish, its smooth and constant but it just doesn't pull like his bike or mine does at the higher rpms.

Right now I'm running #100 mains, and stock needle position.

I was thinking about raising the clip a notch to lean it out through the mid range.

[Jonesy]

All I did on mine was up the main jets to 100's (the originals were 90's), since the pipes were starting to turn gold. I first tried dropping the clips one notch to richen up the midrange, but it was too much and the bike would fall on it's face after giving it a handfull of throttle. Going back to the center clip position with a larger main jet seemed to do the trick, and the plugs (NipponDenso X-22's) have nice gray deposits on them. I'm running everyhting else stock- pipes (although some of the baffling has rotted out inside, likely reducing the backpressure a bit) and airbox with stock filter. Mark (HondaMan) also posted a mod to the spark advancer springs where you cut off one of the end loops and form a new one from the next coil in the spring to delay the ignition advance. You can also change the sprocket ratios as well. I just never got around to doing all that and since my wife loves the bike as is, it hasn't been high on my priority list....

[olds-cool]

Great post, I must have missed it the first time around.  I also took the plunge and worked my head.  I haven't gotten it back together yet so now input on feel.  I took a little more off the "football", flattened it out and made it more like a lite bulge.  I'm glad to see that I created the valleys on the side pretty much the same as you did.  I also opened up the top, just above the valve seat, just a hair.  I kinda took a rounded approach in this area while lifting it a bit.  I thought the first port was the easiest.  By the 3rd port I started worrying about making them all the same as the  first.  I'm sure it didn't help that the cheap diamond bits I was using were starting to wear.  I found the pear shaped bit with the point at the tip was the easiest to use for the shape of the tracts.

[BlindJoe]

For the hard to reach places I ordered some sanding flapwheels and polishing bits from this website http://www.widgetsupply.com/page/WS/CTGY/dremel-sanding-flap-wheel that worked great.
After looking at my plugs I think I'm actually running a little lean so I'm going to lower the needle a notch this weekend and see how it works.

[HondaMan]

All I did on mine was up the main jets to 100's (the originals were 90's), since the pipes were starting to turn gold. I first tried dropping the clips one notch to richen up the midrange, but it was too much and the bike would fall on it's face after giving it a handfull of throttle. Going back to the center clip position with a larger main jet seemed to do the trick, and the plugs (NipponDenso X-22's) have nice gray deposits on them. I'm running everyhting else stock- pipes (although some of the baffling has rotted out inside, likely reducing the backpressure a bit) and airbox with stock filter. Mark (HondaMan) also posted a mod to the spark advancer springs where you cut off one of the end loops and form a new one from the next coil in the spring to delay the ignition advance. You can also change the sprocket ratios as well. I just never got around to doing all that and since my wife loves the bike as is, it hasn't been high on my priority list....

Jonesy:
If you do go back inside: slot that cam sprocket and advance the cam about 5 degrees. Your wife WILL notice that! 

[paulages]

All I did on mine was up the main jets to 100's (the originals were 90's), since the pipes were starting to turn gold. I first tried dropping the clips one notch to richen up the midrange, but it was too much and the bike would fall on it's face after giving it a handfull of throttle. Going back to the center clip position with a larger main jet seemed to do the trick, and the plugs (NipponDenso X-22's) have nice gray deposits on them. I'm running everyhting else stock- pipes (although some of the baffling has rotted out inside, likely reducing the backpressure a bit) and airbox with stock filter. Mark (HondaMan) also posted a mod to the spark advancer springs where you cut off one of the end loops and form a new one from the next coil in the spring to delay the ignition advance. You can also change the sprocket ratios as well. I just never got around to doing all that and since my wife loves the bike as is, it hasn't been high on my priority list....

Jonesy:
If you do go back inside: slot that cam sprocket and advance the cam about 5 degrees. Your wife WILL notice that! 

mark: know an easy trick for slotting the cam sprocket? i was going to clamp a couple pieces of flat bar across the sprocket, then find center and drill a hole, allowing me to rotate the sprocket so the holes could be slotted in the correct radius. ...but i'm no machinist, so i figure i'm probably missing something easier.. 

[CrisPDuk]

Jonesy:
If you do go back inside: slot that cam sprocket and advance the cam about 5 degrees. Your wife WILL notice that! 

Never done this trick on one of these (I suspect I will be doing when my engine comes apart), but if it does the same thing as it did to an old VW I used to own, it'll definitely make her sit up and pay attention



Mark, I'll PM you over the weekend, I finally (at last) got some information from our Customs people this week.