Cb450 performance camshaft

2021 update – click here. Below is deprecated info…

Performance camshafts can add different characteristics of power to your engine.

  • Cams with high lift can add mid range punch, while cams with longer duration can add high rpm top end power.
  • Cams with both can really add power but you need to make sure the head can flow properly.

It really depends on what you’re trying to do and making sure your parts and set up all match. Even if you have a completely stock motor, putting in a cam with a tiny bit more lift / duration can be a benefit. If you add an exhaust and pods, a very mild cam upgrade will yield a couple HP. And… if you have a high compression piston kit you’ll really get a benefit from cams. Especially if you have head porting done.

Megacycle is a cam company that’s been around for a long time. Ever since doing the high compression piston kit in my 450, I’ve been wanting to add a megacycle cam. Megacycle will take your existing camshaft, grind it down. Weld new metal on the lobes, then grind it down to their new beefier specs. This is called hard-welding. This winter I was gonna send my cams out to megacycle. Ironically on eBay popped up a set of used megacycle cams in the grind I wanted for $200 cheaper than new. I bought them.

I’m having a hard time accurately measuring the lift. It’s obvious to the naked eye the duration is way more gnarly. The lobe is much fatter. I’m going to send the cams back to megacycle to have them verified to ensure they’re still within spec and okay.

They’re stamped from 1992 which is when they were made. Pretty cool.

My 450 set up

  • 500t motor bored to a 550cc with high compression Todd Henning pistons
  • 32mm mikuni VM smoothbore carbs / pods (powerbarn.com kit)
  • pamco ignition
  • straight pipes with 8″ baffles
  • head is not ported
  • stock torsion bar valvetrain set up

So I think the megacycle 120-40 cam grind will work well.

My compression at the moment is just over 200psi per cylinder which is a little too high. These cams should lower the cranking compression to around 170 which will be more comfortable.

Intake and exhaust cams below.

Megacycle 120-40 grind


Grinded by Megacycle in 1992

Stock OEM cam profile below

Megacycle profile below. You can see the different color metal welded on and see how much lumpier the duration is. Holding the valve open longer. More top end high rpm power.

Straight pipes with 8″ emgo baffles … get the shit out as fast as possible. Don’t need much back pressure with the type of set up i’m going for.

Mikuni VM smoothbores

17 responses to “Cb450 performance camshaft”

  1. Mike Ashleigh says:

    I’m not super into camshafts, but

    Measuring lift should just be the difference between the fattest part and the skinniest part of the cam profile. You can do this with calipers, but a micrometer would be more accurate.

    Duration is a little more tricky, but you should be able to figure it out with a dial indicator and a degree wheel.

    That’s pretty cool you found those.

  2. Ed says:

    I did measure it that way but the numbers weren’t making sense compared to the spec they list on their site. I called megacycle to ask them why the deal is. They said measuring that way is not accurate. I’m not sure.

  3. Ed says:

    Cool post!

  4. Ron Moore says:

    I think that’s the best looking CB450 I’ve ever seen. Nice job putting it all together.

  5. Brian says:

    My shitty $300 XJ550 with stock cams and bad compression will still take you.

  6. Ed says:

    Haha … Yea your 550 is a 4cyl from the early 80s and my “550” is a design from the late 60s, so yea your shit box is probably faster. But I’ll def still race you. I ain’t scared! Ya never know. I might surprise ya.

  7. Ted says:

    Ed, that power-barn kit looks like a good deal. Am I correct that it includes a 2-1 cable and jets for tuning as well? Might be a good purchase for my Yamaha XS500. Every other kit requires you to buy all the pieces separately. I wonder if the kit with the manifolds would fit as well. It looks very similar.

  8. Adam says:

    Cams are overrated.

  9. Quinn says:

    Now all you need is some heavy duty shocks and that bike might be able to haul your ass

  10. Liam says:

    You measure the lift at the valve, not on the cam. Use a dial guage in the same axis as the valve and measure the lift from seated to max lift while you rotate the cam.

    Those are the exact cam grind I have been hoping to find pop up on ebay, wish I found them first! Let me know if ya wanna sell them!!

    I’m still going through the process of building my CB500T with 74mm THR Pistons, I got the head ported and got new valve guides with viton seals and oversize valves plus Keihin CR33 carbs, just need the cams to go with it all.

    Please update when you install these puppies! And if you haven’t installed them yet sell them to me 😉

  11. Tom says:

    How did the engine run with those cams? I had a set of MegaCycle cams long ago and they ran great. Does yours run a bit flat under 5500 and then take off like a rocket after 6000?

  12. Ed says:

    I ended up not putting them in.
    But yes, the engine characteristics you describe are definitely the way an engine with higher duration cams will act. Thats how my Kawasaki z1 with cams is. 6.5k rpm it takes off until about 10.5k rpm.

  13. Tom says:

    So what did you do with the cams? Did you sell them?

  14. Tom says:

    Ed – just so you know, I now have the cams you had. You decided not to use them, sold them to Liam in Australia, Liam and I met on HondaTwins.net, we decided to swap cams between us (I had bought MegaCycle 120-x11/x12) and I got the ones you sold him – so they’re back in America, and running in my bike. There was a lot of rust inside them and the points side bearing journal was a bit pitted and under spec, so I had it turned down a bit, a bronze bushing pressed into the cam bearing/points base to bring it back to spec, and the street-legal bike runs 8.96 at 76 mph in the eighth mile. Here’s the run – https://www.youtube.com/watch?v=20jFPazXlvU

  15. Ed says:

    Sick man, thats awesome!

  16. Abel says:

    HELP! I have a cb500t, with VM32s and some mystery cams, they appeared to be longer duration with a clear sign of a regrind, measured 39mm lobe height and stock was 40mm. They are in nice shape so i took a chance and threw them in a stock head, stainless straight pipes and messner moto intake pods. Currently running #20 pilot jets, #140 mains, float height at 26mm, needle clipped at the top, and still running too rich, fouls plugs quickly at idle. What could be causing it to run so rich with only one step down left in pilot jets(17.5) ?

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