Jetting and Airflow
So according to my bouncy speedometer, I was getting 25/26mph on the stock pipe and carb. With the Sito Plus, and no other tuning, I was up to 29/30mph. (I haven't had a chance yet to find a friend with a GPS unit to check the speedo against. Hopefully that will happen this week.)
In case I need to go back to stock, I didn't want to mess with any of my original equipment, so I bought a new jet and a "performance" air filter.
My original jet size was 43. I wasn't sure what I had in there, so I bought the smallest size that was easily available, which is a 48. I should have bought another, so that I could find a resonable size, keep it, and then use the other to see how far I could push it by drilling one up a few sizes.
I replaced the stock airbox with a Poloni. The people at 1977 Mopeds said that it would fit, but it's too big (strike 4 for them). I had to put about 3 layers of electrical tape along the inside of output on the box in order to get it onto the carb. The seal seems ok now, and I wanted to ride, so I didn't want to push it, but I'm pretty sure it will pop right off if I pulled on it a little. I might have to send it back and see if the Malossi fits better.
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RESULTS
Jet:
First, I put the size 48 jet in and kept the stock airbox on. I had to lower the idle about a half turn. The bike then ran at 31/32mph, and felt a lot more powerful. The low end is improved, and I get better power off the line -- I don't feel like I have to pedal or push off as much.
Airbox:
As detailed above, I'm not sure if the thing is making a very good seal, but afer I put it on I had to lower the idle by at least a half turn. So either the seal is bad, or the airflow is improved. The stock airbox had three peices of what looked like fine window screen in there, and the Poloni has what I would describe as a loose, open, scrubby-side-of-the-sponge material (I'm sure there's a better word for it somewhere) so I'm confident the airflow would be improved either way.
I didn't take the same route as when I upjetted, I went through downtown and around some hills, so I can't be sure about the speed. It seems like I am now back down to 30/31mph. This doesn't make any sense, though, and the bike feels faster and more powerful. I came very close to running over a cat.
When I get a GPS hookup, I'll test it with the stock vs performance air filter, see what happens, and post it here.
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This gets me to about where I want to be with this bike. I wasn't looking for a lot of speed, just 31/32mph with the least amount of work and money. So far, the most difficult thing I've had to do is drill a new hole in the side of the frame panel for the exhaust bracket, but that wasn't very difficult at all. Including shipping, parts have run me about $75, which is very well worth getting my ped up to a speed that makes it a lot more fun to ride. If you're tryig to save money, skip the airbox.
:M
In case I need to go back to stock, I didn't want to mess with any of my original equipment, so I bought a new jet and a "performance" air filter.
My original jet size was 43. I wasn't sure what I had in there, so I bought the smallest size that was easily available, which is a 48. I should have bought another, so that I could find a resonable size, keep it, and then use the other to see how far I could push it by drilling one up a few sizes.
I replaced the stock airbox with a Poloni. The people at 1977 Mopeds said that it would fit, but it's too big (strike 4 for them). I had to put about 3 layers of electrical tape along the inside of output on the box in order to get it onto the carb. The seal seems ok now, and I wanted to ride, so I didn't want to push it, but I'm pretty sure it will pop right off if I pulled on it a little. I might have to send it back and see if the Malossi fits better.
-------
RESULTS
Jet:
First, I put the size 48 jet in and kept the stock airbox on. I had to lower the idle about a half turn. The bike then ran at 31/32mph, and felt a lot more powerful. The low end is improved, and I get better power off the line -- I don't feel like I have to pedal or push off as much.
Airbox:
As detailed above, I'm not sure if the thing is making a very good seal, but afer I put it on I had to lower the idle by at least a half turn. So either the seal is bad, or the airflow is improved. The stock airbox had three peices of what looked like fine window screen in there, and the Poloni has what I would describe as a loose, open, scrubby-side-of-the-sponge material (I'm sure there's a better word for it somewhere) so I'm confident the airflow would be improved either way.
I didn't take the same route as when I upjetted, I went through downtown and around some hills, so I can't be sure about the speed. It seems like I am now back down to 30/31mph. This doesn't make any sense, though, and the bike feels faster and more powerful. I came very close to running over a cat.
When I get a GPS hookup, I'll test it with the stock vs performance air filter, see what happens, and post it here.
-------
This gets me to about where I want to be with this bike. I wasn't looking for a lot of speed, just 31/32mph with the least amount of work and money. So far, the most difficult thing I've had to do is drill a new hole in the side of the frame panel for the exhaust bracket, but that wasn't very difficult at all. Including shipping, parts have run me about $75, which is very well worth getting my ped up to a speed that makes it a lot more fun to ride. If you're tryig to save money, skip the airbox.
:M
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