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Now you've got one you might as well make it go....

Usual disclaimer - if you blow it up don't blame me.

4 different versions of Parilla cam

Cams are very different on a Parilla - just one lobe to open both valves. They have a hard time. 

This pic has been slightly doctored to enhance the cam profile & show the differences in lift & duration.

The '54 Fox cam is on the extreme right. No sooner is the valve open than it is shutting again.The 175 Turismo usually has an unmarked cam with a lift of about 5mm & no duration (i.e sharp topped). This can usefully be changed for an S if you can find one. These have about 6 mm lift & a bit more duration/overlap. 

The 175 X1 & SS seem to have the same lift at 7mm but a different profile. The X1 having more duration & a more sudden opening. I

The 250 X1 has even more lift at 8mm, you may notice this cam is from a gear drive engine, the others from chain drive.

This only starts to work at about 5k but produces good power up to about 8.5k. 

cam timing touring v X1This diagram compares the touring version to the racier X1

It all amounts to valves opening earlier & closing later - more chance for the gas to get in but only really efficient at higher rpm

Good condition S & X1 cams are hard to come by but there are some being made.

See the Spares section....

 
Suck it in....Brit carb on a Parilla ! Shock Horror You won't impress the concours judge with this one.

Fit a decent carb. Amals are cheap & wear out in 10k miles but have the advantage of working very well & being a doddle to tune. 

 
An SS1 looks wonderful but it'll cost the same to fit it with a new needle & spray tube as a complete Amal Concentric & a few spare jets....and the bike will start, tickover & go 100% better than with a knackered  old Dellorto. 

Blow it out....Unbaffled pipe with Chiuisninininino

The Parilla engine responds well to a straight pipe or reverse cone mega. The pipe shown is a little too long & could be trimmed to advantage.

The bike is very noisy with the open pipe. Certainly the most noisy single of its size. This can be tamed - a little - by a moveable baffle. See the fullsize version of this pic to make it out properly. Known as "silenziatore chiusino" (they can be found in Italy) the baffle can be lifted by a cable operated by a choke lever on the bars. You can see my control just under the back of the petrol tank.