Camshaft choice

[ranton_rambler]

I’ve been offered an unidentified camshaft for my 175. Actually a choice of 2, neither with any colour code. See photo. One is supposed to be a “sporty” profile, the other a “race” profile.
Any thoughts on whether a standard head will benefit from a camshaft update and how to decide which to go for.
Ian

ABFE9AE1-277C-45D2-B81B-DBD4EFB35998.jpeg

[ducwiz]

Well,

I can't recommend one of your cams, as I'm not a n/c specialist. For reference I included a list from the workshop manual:

Snap 2020-10-11 at 14.04.03.png

You can record the valve timing curves and compare them, and finally find out which cams you have.

cheers Hans

[Bevel bob]

My very first ride on a Ducati was on a 175 in very racey trim. We spent hours trying to get it to run. It would pop and bang and splutter out. After many attempts I got one decent up the road blast. It went like Hell ,nothing like anything I had ridden,felt like a sporty 350 Goldie. Never got it to run again.Swapped for a tatty scooter. I now run a hot 250 with a racey cam etc. I will only take it out when I fancy a challenge and there is NO traffic about. These motors have very poor breathing so a hot cam that needs to rev to work will be no use at all. Unless you port it,big valves and carb. Where will you ride it?.

[themoudie]

..... I now run a hot 250 with a racey cam etc. I will only take it out when I fancy a challenge and there is NO traffic about. These motors have very poor breathing so a hot cam that needs to rev to work will be no use at all. Unless you port it,big valves and carb. Where will you ride it?.

That is the million dollar question Bob!

And with Bromely now firmly in the grasp of the conurbation they call "Sarf east", those opportunities are few and far between.

Good health, Bill

[George]

From your previous posts you are looking for comfortable cruising speed of about 50MPH with a little more top speed,
Before you start spending I would suggest you fit the larger front sprocket and give it a run. In theory this should raise speed from 45 to 50 MPH for the same engine revs. and if your lucky a slightly higher top speed. The other thing to check is the ignition advance is 12 degrees BTDC. I seem to recollect that you retarded ignition during restoration to stop kick back. Of course that would mean that full advance is retarded and not good at high revs.

If you decide to change camshaft I would avoid the race cam, it would give poor idling, lower torque/power at low rpm and not comfortable to ride at club meets or riding around town. You would also have to change inlet and exhaust to aid breathing, bike not you unless you get nervous.
Buying a camshaft of unknown profiles may give more trouble than it's worth.

The 175 sport cam would be a good choice but is not a magic answer. To get the best out of it the inlet should have 22mm carb, inlet stub and head inlet. Standard 175TS has 20mm. Ignition advanced to 18-21 degrees BTDC. Compression ratio checked/ adjusted to 8 to 1. Piston, valves and head clearance checked.
If you find this of interest I would recommend buying a copy of 'Tuning for Speed' by Phil Irving first printed in 1948 with updates to early 1960s. Easy to understand with great explanations of how improvements work.
Good luck

[ranton_rambler]

Well,

I can't recommend one of your cams, as I'm not a n/c specialist. For reference I included a list from the workshop manual:

Snap 2020-10-11 at 14.04.03.pngYou can record the valve timing curves and compare them, and finally find out which cams you have.

cheers Hans

Thanks Hans. I measured mine as part of the restoration.
Found some further charts on line so will try and identify the candidates.
Ian

[ranton_rambler]

From your previous posts you are looking for comfortable cruising speed of about 50MPH with a little more top speed,
Before you start spending I would suggest you fit the larger front sprocket and give it a run. In theory this should raise speed from 45 to 50 MPH for the same engine revs. and if your lucky a slightly higher top speed. The other thing to check is the ignition advance is 12 degrees BTDC. I seem to recollect that you retarded ignition during restoration to stop kick back. Of course that would mean that full advance is retarded and not good at high revs.

If you decide to change camshaft I would avoid the race cam, it would give poor idling, lower torque/power at low rpm and not comfortable to ride at club meets or riding around town. You would also have to change inlet and exhaust to aid breathing, bike not you unless you get nervous.
Buying a camshaft of unknown profiles may give more trouble than it's worth.

The 175 sport cam would be a good choice but is not a magic answer. To get the best out of it the inlet should have 22mm carb, inlet stub and head inlet. Standard 175TS has 20mm. Ignition advanced to 18-21 degrees BTDC. Compression ratio checked/ adjusted to 8 to 1. Piston, valves and head clearance checked.
If you find this of interest I would recommend buying a copy of 'Tuning for Speed' by Phil Irving first printed in 1948 with updates to early 1960s. Easy to understand with great explanations of how improvements work.
Good luck

The camshaft is not much money - he’s having a clearout. Main problem is identifying which one is the race cam in order to avoid it.
Yes, less revs at normal road speed is my goal but as this is available I want to see if it might gain me some mid-range. I find the bike is ok on uphill sections as long as the engine can be kept on the boil.
I already have high compression piston and 24mm carb, but I don’t think these do much without decent breathing. Valves are 30/32 with only 6.5mm lift from memory, so maybe the camshaft wouldn’t gain much/anything. And then do I need to look at better springs to cope with more lift?
I have some data to plot out tonight so will see if that helps.
Ian