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A little plea for guidance...

After a decade of on-and-off renovation my 1959 175S is up and running! But not running very well.

The engine has a bit of a FrankenDucati style, as the valves are larger than standard for this model and the inlet tract has been opened up by a couple of mm, but other than that so far as I am aware it's in standard form. Starts well, runs well (little bit rattly, but I know the valve clearances need adjustment from their initial setting). But the bike has little "go" about it. It struggles on most hills, its top speed seems limited to about 45mph, and whilst I never assumed superbike performance from its 175cc engine, I had hoped for a little more pep.

Checking the ignition timing with a crankshaft timing disc today, the points open at about 30deg BTDC static. I guess this means the points cam is at 15deg given the gearing of the 4 stroke engine, but this seems a bit high to me (and the points plate is fully retarded). I tried to show a photo - hoping this worked. Suffice to say that when the crank is at TDC the points cam lobe is vertical: might the points pinion be out of true by a tooth...?

Any glassful from the collective pool of knowledge would be welcome.

Sigean

Hi Sigean

according to this specsheet the points should open 12/ 15 degrees btdc so i would move the timing pinion 1 or 2 tooth over
and go from there

Regards Eldert

I run my 1957 175TS at the book setting of 12-15BTDC static. This is at the very end of the slot in the points plate.
I can get about 65mph from it, but about ~50mph is a nice cruising speed. It pays to change down early on hills to keep the engine spinning.

How is yours for starting? Mine will kick back if the ignition is too advanced.

What carburettor settings do you have? I changed to a modern Dellorto PHB and it took a lot of trial and error to get it working nicely. Luckily a 175 can be held at full throttle to get the main jet size without reaching warp speed.

Is the camshaft timing correct? Unless it is all the original parts in the bevel gear train, you can't assume the dots should all line up. I tried a "sports" camshaft and the valve lift measurements told me that the camshaft needed to be 1 tooth away from the dots.

Ian