Curious about cams

[memper]

The new performance cams are quite expensive. So I was thinking, is there a set of stock cams from another model that might fit my old 750. Like 800 or 900 cams of similar vintage perhaps? I've seen sets on eBay before for under $200. I figure if they fit and have a bit more lift or longer duration it might be worth it to play around.
On the other hand most of you will probably tell me to get 620 heads or something like that...
Did I just answer my own question partially?

[koko64]

True, compatible heads with bigger valves would be great.

Check out Brad's bikeboy.org site for his cam specs page.  Interesting reading. Maybe carbed 900SS cams (93-96 M900), 900ie cams or if you can find them ST2 cams.

Maybe Brad, Speeddog or Duckstew will chime in. I'd ask those guys.

[Cloner]

I'll chime in.....when you change that frikkin' avatar.  You hurt my eyes.     <-----blind glasses

[Speeddog]

Short answer:
Improvement from fitting 900 or ST2 cams is limited by the piston valve reliefs.
They're too shallow, forcing cam timing the wrong direction.
Opening the engine to cut the reliefs deeper (or better yet, fit hi-comps) will allow more appropriate cam timing.

Long answer here:
http://www.bikeboy.org/750ss_900carb_cams.html

695 heads have bigger valves and good cams.
Piston to valve clearance issues to a greater degree, I suspect.

[caperix]

I know that the 900 cams have a differnt base circle diameter, so putting them in will require very large closing shims to get clearance within spec, but they can be installed. At some time Ducati changed the bearing layout on the cams, So it is questionable if the later model cams can be dropped into the older heads. As for full head swaps, 620 heads have the same size valves but better cams. 695/800 heads will get you 900 size valves & better cams than the 620. The 696 would be another step up in valve size & cams, but I am not sure if it will bolt up to the older cylinders.

[memper]

I'll chime in.....when you change that frikkin' avatar.  You hurt my eyes.     <-----blind glasses

Avatar changed...

[Speeddog]

696 heads use a head gasket like DS1k and later variants.

So they won't fit earlier cylinders.

And exhaust ports are different, pipes wont fit.

[koko64]

Avatar changed...

Hooray!!

[DarkMonster620]

so, I could fit 695 heads to my 620 and gain something?

[Speeddog]

so, I could fit 695 heads to my 620 and gain something?

Bore is bigger on 695, so not going to work.

[brad black]

the 2v cams fit into 4 groups.

pantah, 750f1.  don't know much about the 500/600/650 cam.  f1 has the same grind as the later 750 cam, but the vertical is different due to the reversed cylinder.  the hot cam from the montjuich, etc, is just stupidly large, megacycle make a copy of it.

reversed head (paso) onward 350, 400, 600, 750, 900, st2.  same physically as pantah, apart from vertical.  4 grinds: 350/400/600/750, 900 carb, 900ie, st2.  900, 900ie and st2 have a smaller opening base circle, so you need larger opening shims for a 750.  closing base circles are similar.  otherwise they interchange easily.  these cams can be fitted to 400ie, 620, 695, 800 heads with spacers.  vee two made a few different cams, dp made one too.

400ie, 620, 695, 800.  have two bearings instead of 3.  need to be machined to fit previous heads.  two grinds, 620 and 400ie/695/800.  620 has much earlier inlet closing than any of the other cams.

696, 796 (803), 1000 and 1100 "ds" style motors.  totally ditferent to all others.  4 cams, 696/796, 1000/1100, 1100evo and dp.

750 has a few issues, cam and valve size being primary.

[memper]

Yeah, Brad I just finished reading on your site about the 750. Folks arent kidding when they call it a dog. So much work and money to be done to "wake" it up with not so impressive results. I have heard it numerous times: just buy a carbd 900 motor and some hc pistons and fcr's and call it a day.

Well I got fcr's coming later this month and the 900 will come when opportunity and funds allow.

[Cloner]

Since you did change your Avatar I'll share the secret of getting more power from your 750.  Trade it for:



You won't regret the change!   

[DarkMonster620]

Bore is bigger on 695, so not going to work.

how bout cams?

[koko64]

You could get a quote for hi comp pistons, 900 cams, headwork and 43mm inlet valve Vs 900 motor swap (and pistons), then decide. You could put the pistons in yourself and give the heads to speeddog or someone.

If for some reason you couldnt fit a 900 motor in your frame like a 750 Paso or pre 89 Elefant, you could work the small case motor as I mentioned. ( I have been talking to Pasoists and Elefantians). Luckily you can do the engine swap.
The 900s torque is a feel good thing and more important than peak hp for the street.

Your new avatar is honourable and right!