The winter is showing signs of retreat! That means that the moped is being thought about again.
First off is the exhaust. I was underwhelmed by its performance to be honest. I decided to find out why. Peeking in with a flashlight showed that the header pipe extended into the chamber a ways.
Turns out it was in there a good 5 and a half inches. This is supposed to sacrifice peak power for a more gentle, less "pipey" feel. I went ahead and cut it off flush and welded it back together. The result of that was a ridiculous level of noise and no discernible increase in power. That is lame! Add in the fact that this pipe had a habit of melting my right shoe sole so off it went.
Time to play. I spent $10 on an old Yamaha YZ80 dirt bike exhaust
Another $12 on a 1.25" mandrel bend and some scrap rounded it out. I cut off the header on the YZ80 pipe and made a new one that is 3 inches shorter. This should move the tuned length up the RPM range. Dirt bikes have gears and the pipes are tuned to hit low. Mopeds lack gears and need to rev higher.
A bit of welding and it almost fell into place. It just sort of rested into place in a way that looks natural and gives a crazy amount of leg clearance.
The mount for the baffle was quickly knocked out of a washer and exhaust tubing. The baffle is off the tecnigas that was such a turd.
You may notice that I swapped out the handlebars for some clipons. I was making some for my Honda and thought Might as well make some for the moped too. Built is always cooler than bought after all.
So with this pipe the thing really does sound like a dirt bike. It also required some serious upjetting so I know it is working. This is where the new problem starts. I have hit the limit of the Dellorto SHA carb. I went from a 68 jet to a 75 to keep it from going lean up top. Problem is that it is now far too rich at idle and low rpm. The only idle mixture adjustment on an SHA is changing the throttle slide.
the higher the number the leaner the low rpm mix is. The idle port is at the bottom of the bore and the different shapes of the slides allow more air to bypass that port. I have no idea what is going on with number 12 there.
My slide was a #2. First I printed out the picture of the slides, set my angle gauge on number 4 and duplicated it on my slide. It got better but still barely worked. Then I cut the notch like number 7 and it got a little better. Then I hollowed out the backside with reckless abandon and it got a tad better but still choked on fuel and died after 45 seconds of idling. Last ditch effort was to just remove the air filter all together. That did the trick
It works.........sort of. It will hold an idle and it doesn't go lean up high but there is a major low rpm bog that just kills acceleration.
So it is time for a new carb. The only one that technically will fit the Ciao is the one I have so I need to start thinking creatively to make something else work.