OP
UTC

Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
 
Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
UTC quote
Hi all,

My typical steed is a '14 Sprint 150 which hasn't given me any issues over quite a few thousand miles.

But now I'm trying to fix a friend's LX150 (2009).

It's the typical story -- scoot sat for a couple years and now it won't run.

Gas tank had only about 1/8, so I topped it off with fresh fuel, added seafoam and some HEET, and got the bike to start.

Now, it starts right away and idles great, but dies whenever you add any throttle.

So I pulled the carb out and cleaned it, paying special attention to the main jet. Fuel flow appears to be good, no obvious leaks or broken lines. I think the original fuel pump was swapped for a fuel tap. Diapraghm looks good, slide works okay, and I took pains to make sure it was seated right when I reassembled the carb.

Now, if you give the scooter a good thwack of throttle, it'll immediately rev up -- and then bog down and die within moments.

If I open the throttle slowly, the engine will speed up, but beyond a certain point, stop accelerating. I can get the throttle to WOT and the engine still runs, just raggedly and at a speed not much more than idle.

One thing I've noticed is that if the bike sits for a little bit (running or stopped), the first time I throw open the throttle it responds really well (but still dies). But if I do it a few times in succession, the response is a lot less.

I feel like there's some kind of fuel starvation issue happening. Flow from the tank looks good, and I feel like the initial acceleration is a sign that the accel pump is working, but for some reason there's not enough gas at anything beyond idle (or spark? plug cap is tight though).

Not sure what this means. Bad float valve adjustment? Some kind of weirdness with the CDI or coil?

Any ideas?
OP
UTC

Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
 
Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
UTC quote
Should also reply that it appears the evap stuff — at least whatever attaches to the carb — is gone. Just a vacuum hose to the charcoal canister and another that tees to the fuel tap and a solenoid down by the carb.
@ks7877 avatar
UTC

Ossessionato
Joined: UTC
Posts: 2339
Location: So Cal
 
Ossessionato
@ks7877 avatar
Joined: UTC
Posts: 2339
Location: So Cal
UTC quote
Hi monkeyodeath and welcome to Modern Vespa.

I don't have an LX150 so I'm no help. I'm sure more experienced folks will chime in and help get your buddy's LX back on the road soon.
OP
UTC

Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
 
Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
UTC quote
Thanks! Spent plenty of time lurking on the board but not much posting until now.
@greasy125 avatar
UTC

Sergeant at Arms
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 15080
Location: The state of insanity, SoCal
 
Sergeant at Arms
@greasy125 avatar
Weird 80's Vespas & Cool Vintage Lambrettas
Joined: UTC
Posts: 15080
Location: The state of insanity, SoCal
UTC quote
Pull the evap off the carb.

Drain the tank completely and top up with fresh fuel.

Go back thru the carb again.

If you haven’t, throw a fresh air filter at it and maybe a plug.

That should get you there.

If you get jammed up, hit me. I’m in LA and I’ll help you sort it.
OP
UTC

Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
 
Lurker
Sprint 150
Joined: UTC
Posts: 4
Location: Los Angeles
UTC quote
Excellent advice, Greasy!

I drained the tank and refilled it, but still had issues. So I pulled off the carb and really went at it with the can of carb cleaner.

I realized that I'd forgotten to pay attention to the little inlet where the evap hose used to go, and I think that had some crud in it.

Hooked everything up and et voila! Engine finally was able to rev.

I actually had one more problem -- a hunting, surging idle that would die after a bit. I'd mistakenly put a cap on the evap inlet of the carb (fuel injection habits!). Took the cap off and the scoot ran fine with a little idle speed adjustment.

Thanks for the help! Really interesting to contrast this LX150 with my newer Primavera Sprint 150.
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