Topic: CB750 f2 Camshaft on a CB750K7

[Henning Jorgensen]

Hallo

Is it possible to use a camshaft from a CB750 f2 on my CB750 K7 engine, and will it affect annything. I want to keep it as original as possible, but I find it hard to find a K7 camshaft.

Regards Henning Jorgensen
Denmark

[strangedaze39]

Not sure, but welcome!

[jtb]

Should be.

[markjenn]

The F2 camshaft has a lot more lift than any of the K camshafts.  They're not remotely the same, although it may fit.

- Mark

[mazingerzeca]

They have a different part number. I don't know if F2 camshaft's number coincides with any of the K series.

[eldar]

Well you should be able to fit it. The engines were about the same in basic mechanics. What you can do is reassemble everything with the F cam and put the head on without the gasket. Put putty on the pistons first. Then with the head on, turn the engine over. If the valves to not contact the putty, you should be safe then. You MAY want to put in stronger springs though. The k7 springs may not be strong enough.

[MRieck]

It will fit no problem.

[Henning Jorgensen]

The cam fits allright, but when the engine was in the bike and fired up. the pistons and valves were in contact. Engine out again and a another cam from Ebay was oredered, and now the engine is OK

[HondaMan]

Hmmm...IIRC, the timing of the F2 cam is off by a couple of teeth, if the K sprocket is used with the F cam. Checking it with a degree wheel will usually show up this culprit.

[mlinder]

Mark, you are saying properly timed, the cam should not cause valve/piston contact?

Asking because we are looking at waking up a K4 with your tricks, and the addition of an F2 cam.

[HondaMan]

Mark, you are saying properly timed, the cam should not cause valve/piston contact?

Asking because we are looking at waking up a K4 with your tricks, and the addition of an F2 cam.

I'd sure take a look at it. The F2 has more lift and duration, and it runs about 5 degrees later, when used with the F2 sprocket. I'm not familiar enough with the F2 top end to know how much geometry change is involved (rockers-valves-camlobe), but the degree wheel should always tell the story. That, and the clay on top of the piston.

If I were doing it: I'd advance the F2 cam in the early K engine, about 5 degrees from the F2 equivalent. This would make the starting points about the same, and the extra duration would really perk up the top end.

[eurban]

The stock valve springs on the F2 motors are stiffer than stock K ones. Something to keep in mind when using the F2 camshaft . . .

[Leanier]

Just wondering if anyone has gotten any more specifics on putting the F2 cam in a k series engine.  I was thinking of doing this to mine to help add a little bit of power, along with exhaust jetting and pods.  Anyone tried it?  Were the results worth it?  And what all modifications were needed?
Thanks!

[HondaMan]

I just installed an F2 cam in a K8 engine. It went in fine, is cold-blooded, though. It's that late-duration thing. We'll be tearing it down in the near future for more cosmetic work and an improved F3 head, and I will probably advance the cam then to improve on the starting and cold-bloodedness.

[MRieck]

It will fit no problem.