I realised i had a nice 18mm Delorto from an old 1950s Garelli. Turned up an inlet manifold ...wow...the power difference from the old stock unit is crazy. Beautifully made carb. Jetting seems perfect. Wish I had faced off another 6mm to give me more space to fabricate an air filter. Needs some brakes also.
Thanks. The front of the pipe was rotten when I got it so I cut it back to where the steel was solid, fabricated a new extension of the diffuser. The original pipe was a larger diameter at the cylinder though. Long story short I think I need to add about 2 inches to the header. This motor is about 12 years old. But fairly low total hours. Inlet port is actually quite big. Its a pity the stud spacing is so close together on both manifolds.
So next steps Air filter, brakes, lengthen header.
Respect, Snorks that vintage Dellorto is a great carb which will improve performance on the China girl and support aggressive tuning of these engines, like your expansion pipe. I've used these Italian made carbs on both 2 & 4 cycle engines since 1960 the first was on a modified 8 hp Cushman Eagle (a round slide Dellorto) and have used both round and flat slide Dellortos on many projects since. They are really well made. The Chinese SHA clones don't compare by any standard to the new Italian made flat slide Dellorto, except in price and the new Italian made carb doesn't compare to the vintage carb either, except in price. The old ones are hard to find in decent condition though and can cost a lot.
Good find I wish I had a dozen of them just like yours. I'm a fan. Just to show I'm not a hater I have a couple of SHA clone carbs on my 66cc motors that work fine and produce a little performance boost, but nothing like the real Dellortos provide especially when tuned to work with a quality expansion pipe (KTM or Yamaha etc.)
Thanks Rick, Years ago I supercharged a Honda 50cc minibike and used a 17 mm flat slide delorto from a 50ccFantic super rocket. The 'blower' was the guts of a pneumatic sander ( rotary vane pump) pressed into a slug of aluminium and driven at about 2.6 to 1 from a tiny v belt from a vacume cleaner (drove the brush on the front) I machined a groove in the hitachi flywheel. It sounded like a dentist drill. It really needed some of the overlap taken out of the cam and the fuel pooled on extended idling. The plenum was also a little too big at 200CC and was supposed to be between 50 to 100 % of engine capacity when blowing singles. I never had a set of jets and that carb was a bit too rich - but an awesome carb non the less. I ran a little 2 stroke oil to prolong the bakelite vein life. This was back in about 91 or 92 pre internet days. I found out later that clutch baskets (driven at engine speed!!) let go at around 10 or 11K rpm.
If I ever were to ever see a good vintage delorto I wouldnt hesitate. Why dont more people use a straight mainifold? Cant stand the gooseneck stock thing.
I added a few inches to the header (exhaust even lower) but feel Im limited by the stock timing now...