Camshaft 2S vs.PW3

There is some correspondance   about this on the Access Norton Forum , Bear in mind that its a completely different "scene"  over in America  that  has little relevance to our type of motorcycling.!!.

the main point is that PW3 swap, on its own, will not give more mid range , in fact often less. The original standard cam is a vg ALL ROUND cam if other  factors are standard.

Having never found any Commando to really be missing on mid-range, what are you comparing against? And what rev range do you call mid-range?

As a general point, most of the race camshafts, 4S, PW3 etc. work best on the bigger bores of 850s/750 short-strokes; PW3 reported to give better spread of power than the 4S (although I still think the 4S is better for racing). Like Jan, I wouldn't expect a PW3 to give you anything over a 2S without a lot of effort; certainly not a swap 'n go.

There are quite a few things you could look at that might boost/restore the mid-range of your Combat - almost all of which are cheaper and more likely to deliver.

"There are quite a few things you could look at that might boost/restore the mid-range of your Combat - almost all of which are cheaper and more likely to deliver"

What would they be Stan? He presumably already has the 10:1 compression but intrigued to hear your suggestions!

If Jakub is still here I agree a standard cam is a good start but have no personal experience using it on a Combat with it's bigger carbs. On an 850 street bike, stock or tuned it's excellent. I use the USA Web#312 version with slightly higher lift and 0.006" valve clearances.

Just enjoy your Combat in that case! Keep it in good tune using Super Unleaded fuel and check it has the 19T front sprocket which I believe was standard. A higher gear would make the low/midrange feel worse. Where are you based?

Neill, the OP hasn't told us what he thinks of as mid-range or what he's comparing against, but here are some thoughts.

If the OP's mate on a similar Combat leaves him standing in a 65-80mph top gear roll-on then the first question I'd have would be are they running the same gearing. If, however, he's comparing the same roll-on against a BMW R1250, well what do you expect from a 50 year old bike with 2/3 the capacity.

Having ridden both standard 750s and a Combat when these bikes were just a few years old ('75 on), I don't recall ever thinking the Combat was missing mid-range (which I'd put at 3500 - 5000 rpm). The Combat just had more the other side of 100mph. I've never seen dyno plots for these bikes but I would guess that if the 2S looses anything to the standard cam mid-range, the higher compression and bigger carbs/inlets evens it out.

As for what the OP might do. First, just make sure it's in good tune.

Then undo the 'improvements' people might have made over the years: compression plate (for easier starting), single carb, K&N air filters, restrictive exhaust.

After that, how knackered is the engine: worn cam lobes, piston rings, valve seats and guides, carb slides/bodies. advance/retard.

Finally, cheap upgrades that really do improve on original items: electronic ignition, vernier camshaft sprocket, quick action throttle.

Nothing revolutionary, no well-kept secrets. The Combat was/is a quick bike for the period and a good one doesn't need any snake oil for everyday road use.