Topic: CB650 cam specs?

[Scott S]

 I've searched and searched and just can't find all the cam specs for these cams.

Here's what I HAVE found:

SPECS:
 
 Stock (1974) CB550 cam
 
1.36 exh.       lobe              1.38 in.
1.110           base circle       1.110
0.252              lift              0.272
 
CB650 cam
 
1.39 exh.       lobe               1.40 in.
1.110            base circle       1.110
0.280             lift                0.293
 
 Can anyone give me the duration?
 What ratio are the rocker arms?
 Are the CB550 and CB650 durations the same?

[Scott S]

 Anyone?

[Greggo]

I'll subscribe.  I only know 'seat of the pants' differences   

I do know there are two versions of the 650 cams.  IIRC, the earlier '79-'80 cams are hotter than the later ones.  Someone else mentioned all the German market cams are the wimpier, emissions restricting version.

[Scott S]

 I think all the '79-82 CB650 cams are the same EXCEPT for the low HP German versions.

 I can't believe I'm having such a hard time finding these specs. I have a factory manual, aftermarket books, have searched this forum, etc.

 I'd really like to know:
-CB550 duration
-CB650 duration
-stock CB550 rocker arm ratio

[Frostyboy]

I don't have the answers you want, but there's a "contact" link here. They might have the standard specs you're looking for seeing as they do grinds for them.
http://dynoman.net/engine/cams/webcams_honda.html
Good luck.

[Scott S]

Some good info a fellow forum member sent me in a PM. Thanks Kemp!

Here's the info I have on the CB550/650 cams. Unfortunately I do not know the rocker arm ratio and have not seen that info published. Would like the answer to that question also. The text below is cut and paste from articles and notes from others on the forum.

OK I found specs for Yosh cams.

Street special part# YH500-121-00

IN opens 20 BTDC, closes 50 ABDC  .278 lift
EX opens 50 BBDC, closes 20 ATDC  .307 lift


TT Special race cam  #YH600-122-00

IN opens 27 BTDC, closes 57 ABDC  .324 lift
EX opens 56 BBDC, closes 27 ATDC  . 336 lift


From another post, the lift on stock cams is:

CB650    IN .280 
            EX .293

CB550    IN .252
            EX .272

It looks like the 650 isn't too far the Yosh street cam as far as lift, not sure about timing?
In corresponding with hymodyne I guessed the 650 cam would have about .020 more lift than the 550 cam. Kayaker's #'s say I was close. I also guessed about 10 degrees more duration at least on the intake.
think .030 or so more lift would have a miniscule effect on ramp angle, but more duration would add to it. No matter what, lift is good, but its the timing that matters. The most important timing event as far as "feel" is intake closing. Closing later moves power up the rev range because it gives more time to fill at high revs.

[Scott S]

I was also given some specs for the stock CB550 cam from a 1980 Action Fours catalog:

 intake duration 240*
 exh. duration    245*

 intake lift     .300
 exh . lift       .280

 Using the numbers I posted earlier, this would give me a 1.1:1 rocker ratio, right? (.300 divided by .272 equals 1.10. Using the same math for the exhaust side gets me 1.11.)

 That would mean the CB650 cam has .322 intake and .308 exhaust lift at the cam, right? (And possibly more duration)
 Those kind of lift numbers put me in the FK10-ish  or larger range, right?

[Danno]

the 650 cam has a slightly higher lift and about 8 degrees longer duration it is great for the 550 as a modest performance mod but the cam tunnel has to be modded a little an extra groove added to use it and you have to use the 650 tach gear

[dave500]

a while ago i degreed a 500 to find out the timing specs,ive got it written down somewhere,ill dig it out.

[dave500]

at 40 thou i came up with
ex37/2 lift 279 dur 219

in5/31 lift294 dur 216

[Scott S]

at 40 thou i came up with
ex37/2 lift 279 dur 219

in5/31 lift294 dur 216

 Dave, can you clarify those lift #'s? 37/2 and 5/31?

[Scott S]

the 650 cam has a slightly higher lift and about 8 degrees longer duration it is great for the 550 as a modest performance mod but the cam tunnel has to be modded a little an extra groove added to use it and you have to use the 650 tach gear

 I have the 650 cam lift #'s, just trying to find the duration. So...add about 8  degrees to th 55o duration?
 What do you mean by "cam tunnel"? I clearnced the head to clear the 650 cam already. Will check rocker cover soon. I have the tach gear, but what do you mean by "an extra groove added"?

[dave500]

37/2   5/31  this is at 40 thou,some numbers from where ever may be at zero lift .

[Scott S]

 I don't know what the 37/2 and 5/31 mean....

 Also, our lift specs are pretty close, but the duration #'s are different.

[dave500]

the 5/31 and 37/2 refer to the opening and closing points in degress like inlet opens 5 btdc and closes 31 abdc,exhaust opens 37 bbdc and closes 2 atdc,,these arent gospel figures,just what i came up with tinkering,measured at 40 thou lift,if you do it with no lift and clearance the numbers change significantly,cars are generally measured at 50 thou and bikes at 40 thou.

[Scott S]

 Bumping this one up. I'll be taking a stab at degreeing in a 650 cam soon (milled the head and I just want to learn how to do it and maximize the engine combo), and I'd love to find any more information, if possible.

 Specifically, anyone know the duration and/or timing events? Like what Dave listed above for the 500 cam?

[jbraun]

Im far away from you guys in knowledge regarding this, just been starting to scrape on the layer of knowledge around swapping the cam from a CB650 into a CB500. Been trying to get the info if its a clean swap or do I need to do anything more?

[dave500]

the cam is a clean swap providing you test it first by laying it in the rocker cover and turning it and check if lobes hit anywhere,if so you can buzz that off,also check the lobes don't hit the underside of the actual rocker arms,do the same in the head,lay it in and rotate it to see if the lobes foul anywhere,youll need the 650 tacho drive gear aswell.

[jbraun]

the cam is a clean swap providing you test it first by laying it in the rocker cover and turning it and check if lobes hit anywhere,if so you can buzz that off,also check the lobes don't hit the underside of the actual rocker arms,do the same in the head,lay it in and rotate it to see if the lobes foul anywhere,youll need the 650 tacho drive gear aswell.

Sweet! Thanks for your answer!

Sorry for stealing the thread 

[RAFster122s]

650 cam requires a tach instrument change to same ratio of either 650 or 750...keeping in mind the high 550 redline band starting at 9500 rpm.

[flatlander]

not only tach instrument (clock) but you also need to change the tach gear.

[RAFster122s]

not only tach instrument (clock) but you also need to change the tach gear.

Yeah, Dave had already mentioned that...

[jbraun]

Hi guys! Just one more question do I need to change anything else in order to get it working? Stiffer springs maybe?

[Scott S]

 The 550 springs are fine.

[jbraun]

The 550 springs are fine.

I have a 500 tho, still the same?

[Scott S]

The 550 springs are fine.

I have a 500 tho, still the same?

 Yes.

[ralt12]

How would you source the Yosh street cam these days ? Don't see a reference to any 500-550 engines on their website....