Topic: WANTED :- Mild Cam for CB550

[caferacer]

i have a 1978 Honda Cb550 that i started racing last year with the VRRA in Canada , the engine is stock and in need of a little performance improvment .
So i am thinking of doing a little porting on the head maybe a little over bore and a mild cam but i am not sure where to find the cam , can any one tell me the best place with the best value as budget is tight .

Thanks Caferacer

[calj737]

A 650 cam is your cheapest option. Be certain to also swap the tach gear for compatibility.

[bwaller]

Hi caferacer,

Not sure who I'm talking to but we race the same class. (although my 2013 season was short) 60mm is the largest legal bore, but even with stock pistons you can do some decking to build stronger CR. Be prepared to check all clearances though. As mentioned the CB650 cam is a mild increase over stock, probably like the Webcam 358a. They also sell the 358b, plus Megacycle has cams available too. Dynoman offers some 550 engine upgrades including 60mm pistons.

Check the VRRA for sale section. Dan has a set of Yosh 1mm over pistons with a set of bored cylinders as another option.

Cheers,  Brent

[onepieceatatime]

I have an extra CB650 cam, but do not have the tach gear to go with it. PM me if interested.

[caferacer]

Hi Brent it is Dave from Tech #734 the light blue 550 , thanks for the info i will chequ it all out , i am interested in the cam i will PM you onepieceatatime and thaks calj737 .

Dave

[caferacer]

Brent could you Pm me and let me know which Dan to contact on VRRA site please .

[Tintop]

Here's the link to the ad - http://www.vrra.ca/board/viewtopic.php?f=21&t=20844 

[Justind97]

Here's the link to the ad - http://www.vrra.ca/board/viewtopic.php?f=21&t=20844

Already sold to me.   I'm picking them up Wednesday when Dan gets back from his trip.

[caferacer]

I snooze i loose ,see you all at the track .

[flatlander]

does anyone have a comparison between the mentioned cams in a 550?

• cb650
• webcam 358a
• megacycle 126-00

would be interesting to know where they put the powerband, compared to each other (and compared to stock).
there seems to be a lack of info in the 'mild cam for 550' segment - or at least i could not find any hard facts when i searched the forum.

[Justind97]

Here's some info that I could find for you.

550(1974)
1.362 lobe            1.382
1.110 base circle   1.110
0.252 lift               0.272

650(1981c)
1.360                1.380
1.105                1.105
0.255                0.275

650(1979std)
1.390                1.403
1.110                1.110
0.280                0.293

Taken from here:  http://forums.sohc4.net/index.php?topic=99529.msg1111277#msg1111277

Webcam 358a
VALVE LIFT     DURATION      DURATION
                                               @ 0.050"
   
.330/.330       280°/280°      228°/228°

Taken from here:   http://www.webcamshafts.com/index_blank.html?pages/vehicle_search.html


Megacycle Cam

Copying and pasting isn't working too well:   http://www.megacyclecams.com/catalog/catalog.pdf
 PDF page 28/69
 

[bwaller]

I installed a Web 58a at the same time as a bore increase, but my best guess is it mimics the stock Honda cam. Meaning, the power delivery is very linear only somewhat stronger. No peakiness anywhere with this cam, good choice for a street bike.

[flatlander]

justind97:
thanks for the numbers. i've seen them for megacycle and webcam but not for the stock 550 and 650 cams. good find!

adding from the same thread, for easy comparison

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

and

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

in5/31 lift294 dur 216

and for the megacycle 126-00, from http://www.megacyclecams.com/catalog/catalog.pdf

valve lift
.296"/.280"

duration at 0.40"
240/240

open/close
in: 15 btc/45abc
ex: 45 bbc/15atc

bwaller:
thanks a lot, that's good practical info. if i read you correctly, the 58a is just overall a bit stronger, does not sacrifice any midrange?

looking at all these figures i'd guess the megacycle to be generally somewhat milder than 58a but possibly more torquey - but i'm not great with numbergames and this is quite a theoretical excercise. has anyone tried it?

[bwaller]

It's probably not a perfect comparison because the engine I mentioned is 592cc but it does have a very smooth power delivery.

This winter I changed the copper for an MLS head gasket and the timing figures are as follows. I always check @ 0.040" not the 0.050" Web suggests. This gives some real comparison #'s.

@0.040"

In. opens 14d, closes 47d       106.5d  lobe center
Ex     "      47d,     "     14d.      106.5d         "

Intake duration 241d    lift  0.314"
Exhaust     "      241d    lift  0.315"

[flatlander]

thanks again, bwaller!
here's an overview of what (i think) the info in this thread is so far:

	58a 0.040	58a 0.050	58a	126-00 0.040	550 0.040	550	650 1981c	650 1979std
in dur	241	228	280	240	216	240
ex dur	241	228	280	240	219	245
in lift	.314		.330	.296	.294	.300	.255	.280
ex lift	.315		.330	.280	.279	.280	.275	.293
in open	14			15	5
in close	47			45	31
ex open	47			45	37
ex close	14			15	2
in lobe ctre	106.5			105
ex lobe ctre	106.5			105

if anyone spots an error or something that's missing let me know, then i add it.

[kayaker43]

Ignoring the numbers I can give some real world feedback regarding the 650 cam swap. I was pleasantly surprised to find the sweet spot come in about 1000 rpm earlier than the stock cams with a little more power all the way to redline. The exhaust even sounds s little different. For street use its a great cam however roadracing is mostly in the upper rpms and may not see as much benefit.

I would retard the cam to move the sweet spot up a little higher but check clearances first.

[bwaller]

Good to see you Kayaker. Chek for a PM please.

[Kemp]

Noticed a really big improvement over stock 550 when I went big bore (591CC) and used the 650 cam in an otherwise stock motor. The engine was a lot more responsive with a big boost in mid range and top end. Bang for the buck I think it's the best way to go on these 550's.

[flatlander]

some bits out of an earlier email conversation with buzz from dynoman:

The CB 650 cam has less duration than even the Web 358 A drop in cam and the 358 B has even more duration than the 358 A for better flow. We know that many people use the stock CB650 cams in the CB500-550 but they do not make the high RPM power of a performance cam ,as they are emissions cams. For the street they work better than the stock CB550 with low compression pistons, but we have to disagree on there overall performance being better. With a bore kit with higher compression you need a cam with better ramp speed and more duration for the extra flow in the high RPM range. This not only charges the cylinder much better, but the motor will run cooler as well.

If you change nothing else a higher lift cam with low duration (like the CB650) may add a little mid-range but will fall off on the top end without added duration. If you are going to install [bigger bore, higher compression] pistons your mid-rage will be fine with a 358A, but if you are going to keep the stock pistons your mid-range power will be lower with any cam that you install.
With a bore kit installed the 650 cams would give you more mid-range power than cams with more duration, but with a better cam you would increase the top end as well.

[onepieceatatime]

Here's some info that I could find for you.

550(1974)
1.362 lobe            1.382
1.110 base circle   1.110
0.252 lift               0.272

650(1981c)
1.360                1.380
1.105                1.105
0.255                0.275

650(1979std)
1.390                1.403
1.110                1.110
0.280                0.293

Taken from here:  http://forums.sohc4.net/index.php?topic=99529.msg1111277#msg1111277

Webcam 358a
VALVE LIFT     DURATION      DURATION
                                               @ 0.050"
   
.330/.330       280°/280°      228°/228°

Taken from here:   http://www.webcamshafts.com/index_blank.html?pages/vehicle_search.html


Megacycle Cam

Copying and pasting isn't working too well:   http://www.megacyclecams.com/catalog/catalog.pdf
 PDF page 28/69

For US models '79 through '82  CB650s have the same part number for the cam. This applies to standard, custom, and nighthawk models. The German ones had a different cam that was not an upgrade for the 550.

[flatlander]

adding to keep all these numbers in one place:

Here are some CB 650 numbers from the lady at Megacycle. They look a little different than the numbers I measured using my cheapo calipers, but what do I know?
 Do these numbers look viable for a stock 650 cam?

 INTAKE

 .332" lift at .040, measured at zero clearance.
 223° duration
 105° lobe center

EXHAUST

 .318" lift
 228° duration
 108 lobe center

[flatlander]

here's a dyno comparison of the megacycle 126-00 and webcam 358a.

they're in the same engine. both were installed the same way: equal lobe centres, and valve lash set at manufacturer's spec (they use different amounts).

the 358a reaches max torque earlier, while both get to the same hp. my butt dyno confirms this also, by reporting noticeably stronger pick-up from lower rpms.
of course, results will be different with different engine configurations...

[turboguzzi]

54 hp is nice going for a 550. engine has other mods other than cam?

[flatlander]

yes:
59mm wisecos, stage 2.5 mike rieck head with +1mm intake valves,
stock airbox and carbs, benelli replica 4/4 pipes, boyer bransden ignition

[Erny]

I'm going to refresh this old thread

I'm somehow forced to rebuild top end of my 550K1 (motor is now 100% stock, 17k miles total, due to rotating rocker arm shaft I need to address worn rocker, worn camshaft and fix eliptic hole in valve cover)

As top end is now open, I'm seriously considering to change cam to alternative one with aim to improve torque/power character of the engine.
I want to keep stock pistons, valve and springs. Head to be rebuild / milled / ports to be matched with intakes, new piston rings (hoping no re-boring needed).

As I understood from this thread and also other ones there are few options:
- stock cam from CB650
- webcam 358a
- megacycle 126-00

Considering keeping rest of engine stock, which one would you recommend and why?
if CB650 one - looks there are 2 types existing, 14101-426-000 and 14101-426-690 (for Germany only?), which of these 2 I should look for?
Of course another pb will be to find one for acceptable price..


To flatlander - dyno results you posted in post#21 http://forums.sohc4.net/index.php/topic,134461.msg2025855.html#msg2025855 not showing up, can you eventually re-post it?

At the end, I need to decide if I will go for my cam repair (only 1 lobe is worn) or I'll install some alternative, hoping for better performance