Modern Vespa

Hey all - just registered but I've been browsing here for quite some time.

Latest issue has me stumped, I'm afraid. A couple weeks ago my Fly 150 lost power mid-ride and would not start back up. After poking and prodding around for several days, I finally noticed that the bottom hose attached to the fuel tap had a huge crack. Replaced it with ~3" of new hose just in that short section between the fuel tap and whatever connector it goes to right there.

Now the scooter starts up just fine, and runs, except only reaches about 25 mph before it stops accelerating. I can get it up to 30 or so with the throttle all the way open but it takes a long straight road because the needle just crawls upward. It feels like it's being governed somehow, or the engine just isn't getting what it needs any more, because when I open up the throttle I just don't get the same zippy response.

I've gone back through and tightened all the screws, tried to undo all of the things I did in trying to solve the initial problem but honestly I've got no idea what could be causing this strange behavior. If any of you guys have experienced this or have an idea what could be wrong, I'd appreciate the advice!

-Brad

Your fly is carbureted, correct? sounds like for some reason it's not entering the midrange. Could be a clogged jet from sitting, or it could be that you still have a vacuum leak.

Thedodus, can I ask you a question. I have a 09 fly 150 too. I was wondering for your transmission level what line is it on when reading from your dipstick. Also I currently have 1000 miles on mine, when do you recommend to adjust the valves. Thanks

Did you do anything to the carb or did you accidentally knock it with your hand? Never looked under the hood of a Fly and i don't know if the auto choke is anywhere near the hose but when my auto choke wasn't seated correctly i couldn't get my scooter above 30. Don't know if that's the problem but check that. Good luck

Honkerman: thanks for the suggestions. I'll try messing with the carb.

Mike: my dipstick has oil all the way up covering all Xs. As for valves, I have heard that around 3-4k is when it becomes necessary. I have not adjusted mine, wanted to try a lot of things first. There's a lot of info in these forums about valve adjustment on Flys.

Judy: I may have bumped the carb a bit. I definitely fiddled with the auto choke a bunch - and it does feel like something along those lines - but I disconnected the auto choke (I think) and it didn't change anything... So I'm stumped. Maybe I should remove the whole auto choke somehow.

Thanks guys. I'll keep messing around and report back

Hi mate,
FYI if you disconnect the choke wires you automaticaly make the choke default to ON without ever going off.
The valves should be adjusted on its first service circa 600mls.
Cheers Andy

hi, I meant the dip stick that is in the back that allows you to measure your gear oil amount. mine has lines on the back of it. I posted a image of how mine look like. Thanks again

Andy: no kidding!! So is there a way to disable the auto choke that makes it be off? Because it does seem like theres a choke issue.

Mike sorry for the confusion. Where is that stick coming out of, can you take a picture of the location?

if the one section of the line was bad, i'd recommend replacing the entire thing. including the vacuum line. eliminate the one way valve on the vacuum line and double check the the T-fitting and line to the SAS hasn't been compromised as well.

if you had the carb apart in any way, i'd suspect that the diaphragm wasn't seated properly. check the evap port of the carb while you're there and you should be good to go.

-g

it is located in the picture. Right under the shock

God what a idiot, i meant diaphragm. Thanks Greasy. It has to be perfect.

Amazing, lots to go on, thanks guys. Hopefully can fiddle tomorrow.

Mike - checked mine and oil goes up to the second line. Does that help?

Replaced the entire vacuum line up to the t-joint (ditched the one-way valve) and that was totally the trick!

Acceleration/top speed/throttle is all back to normal.

Thanks everyone for all your help!