Topic: The Questionable CB750 Camshaft

[Industrial Cafe]

the previous owner of my bike tells me it has an aftermarket cam. i think he said webcam street cam, from what i gather that's a .360 .280
I need to know how I can tell what camshaft is in the bike.

there are very few markings on the cam.
here is whats on there.

the letters A E stamped into a raised block on the left side between lobe sets.
and an R5 stamped next to the cam gear.

anyone got any ideas? I think it might be stock

[754]

Is the AE stamped in or cast?

Measure the fattest part of the lobe, if it out of the head or you can get in there.
Check end of cam for markings.

[MCRider]

the previous owner of my bike tells me it has an aftermarket cam. i think he said webcam street cam, from what i gather that's a .360 .280
I need to know how I can tell what camshaft is in the bike.

there are very few markings on the cam.
here is whats on there.

the letters A E stamped into a raised block on the left side between lobe sets.
and an R5 stamped next to the cam gear.

anyone got any ideas? I think it might be stock

The "R5" is a Honda mark, so to be "aftermarket" it must be a regrind where they cut down the base circle to give the lobe a diferrent perspective, or weld up regrind. If its a weldup regirnd its easy to tell by looking at the side of a lobe. The seam between the old cam lobe and the added on weldup material will be evident.

Or else i'm completley off track and you'll just have to measure it.

The AE might be "Andrews "E" grind" Andrews got out of CB750 parts some time ago. But he said it may be a WebCam in which case never mind.

Sorry this is not an answer to your question, just more speculation.

[Industrial Cafe]

to MC Rider, 
                 the headwork was done in the early 80's, so it might be this Andrews E grind you speak of.

to 754,
         the A E is stamped with what i would say was a hand punch, the top of the E is light.

I measured the lobes at their peaks with my trusty old inch caliper.
ex. is 1.382
in. is 1.408
don't know how to measure duration :\
not sure if I'm measuring it right. any suggestions?

[Tower]

Duration is simply the angle from the point a valve begins to open to the point where is just closes.  There are wheels and tools for this, but you can do it with a pencil/scribe to within a couple degrees of accuracy.

• Mark the cam with a line on its end (if it doesn't already have a line scratched into it), like etching one line of a cross hairs that run through the cross-section centre
• Twist the cam to a point where a valve just begins to open tips:slip a tiny bit of a long sliver of tin foil under the valve seat - this will fall out just as the valve opens, or, pour a little gasoline into the port - which will begin to drip just as the valve opens, or use a gauge, etc
• Mark the head at the point the cam mark passed just as the valve began to open.
• Continue to twist the cam
• Mark the cam cross-section a second time, at the spot where it passes the mark on the head, just as the valve closes.
• With a protractor, read the angle between the two marks on the cam end
• Take note whether the cam has turned past 180^o and if so, add 180 to your angle, and if not, subtract your angle from 180, to get the duration.

[Industrial Cafe]

i did a math problem...
shortest height of the lobe minus tallest height.
ex =0.285
in =0.300
i think i moved my thumb last time i measured

thanks for the help tower, i'll look into it, if it shows up not to be a stock lift.
         
          p.s.what is stock lift int. and ex. on the cb750?

[Industrial Cafe]

the cam has what appears to be 2 different metals like a welded section onto the tip of each lobe.
or its just wear, but the cam cam doesnt seem worn at all

does anyone have a stock cam and some calipers lying about?

[754]

Sounds like a regrind, a bit hotter than stock. That is why I asked if those letters were stamped as stock they are raised.

Clymer manual give a spec to measure stock lobes.

[Zig]

the cam has what appears to be 2 different metals like a welded section onto the tip of each lobe.
or its just wear, but the cam cam doesnt seem worn at all

does anyone have a stock cam and some calipers lying about?

my 75/750 intake "cam" lift is .296, exhaust is .283. web cam or megacycle lists stock intake lift as .315 cant remember exhaust#, they dont say what year that # was for.
i believe that diff cam profiles were a way to detune the engines as years progressed??
my andrews D grind = in .380 x .360

[Industrial Cafe]

hmm...

[HondaMan]

Stock lifts are about .300" to .315". If the lift is more than .330", the head needs porting to use it, as the port profile doesn't flow much more than that.

[754]

Geeez... I am running about 375 lift with stock ports and valves, and its a lot of fun to ride.

I do have a ported head for it now and realize it will get more power, hope I dont lose any midrange though..

[donny]

my Andrews A is well stamped on the end.
I would guess all Andrews cams are so?

[HondaMan]

Geeez... I am running about 375 lift with stock ports and valves, and its a lot of fun to ride.

I do have a ported head for it now and realize it will get more power, hope I dont lose any midrange though..

You're probably benefitting more from the extended duration than the lift, if the head is stock. It really takes a step up with porting. If you stay with the 28mm carbs, the flat spot won't be too bad, even with a Stage 2 port job.

[754]

I am running the Webers with 30mm venturis..

[HondaMan]

I am running the Webers with 30mm venturis..

You've got extra HP lurking, just waiting to be freed!