Modern Vespa

I had an interesting experience on my 2005 PX150 a couple of evenings ago.
I was in the middle lane of 3 lanes in moderate traffic when I lost all throttle response.
The engine continued to idle but would not respond to the throttle.
Luckily, since the engine was idling I still had turn signals and could make my way over to the side of the road without getting run over.
After pushing the scooter down the sidewalk for about 2 blocks I found a suitably illuminated area to start to work on it. (Now I know to keep a flashlight in my toolkit )
During my walk I was assuming that the throttle cable had broken but I had a spare with me so no problem.
Once I got the box opened up and the air filter out of the way I realized that the throttle slide rod had come out of the linkage to the throttle cable.
I put it back on and went on my way.
Two days later (after dark again) I went to Home Depot and bought a suitable flashlight, and on the way home I lost my throttle again.
While putting it back together again this time I worked the throttle back and forth several times and I could see the rod rising up out of the linkage.
Sometimes it would fall back down, sometimes it would stay up.
So I took my needle-nose pliers and made an oh so slight bend in the rod to help it stay hooked in.
This, of couse, raised my idle a little but I figured I would just adjust it tomorrow in the daylight.
The next day I found out that adjusting the idle screw would not get my idle back down to where I wanted it so I thought maybe I put too much bend in the rod.
After consulting the Service Manual I think I have discovered that the rod should be entering the linkage from the bottom.
Mine was poking down from the top.
I had my carb rebuilt almost 3 years ago and it had been working fine, up to this point.
Should I just straighten out the bend I put in the rod and stick it back into the linkage from the bottom?
Or do you think I might be having other issues?

Yes, it should be coming up from the bottom. If you put too much of a bend in the rod, you should straighten that out. A slight bend at the end shouldn't matter.

Thanks for responding.
Yeah, I just put a little bend it on the short end of the "L".
I'll put it back right and invert it.
I still kinda' wonder why it lasted 3 years before it decided to act up.
Maybe it was sun spots, or something.
Thanks again!

Sorry. I misunderstood the part you were talking about. The hook that links the carb slide to the oil pump is inserted to the pump arm from the top. But you still need to make sure that the length of the rod is not bent. Also, sounds like your cable might be too tight. Use the adjuster on the front of the carb box to rectify that.

OK, now I'm confused.
I found a better picture in the Stella repair manual and it actually is a better representation of my Vespa carb than the drawing from the Vespa Service Manual.
It too shows the short end of the "L" pointing up. (The Stella one does have an additional bend in it that mine does not. Mine is almost completly straight until the "L" bend.)
But you're saying that mine was correct with the "L" pointing down?

I have noticed that my hand grip is not springing back the way it should.
The throttle rod has plenty of snap to it when it's not attached to the linkage and the cable doesn't have much resistance to it when the throttle rod is not attached.
I figured it was the return spring in the headset and I was going to tackle that this weekend.
I hope it's not broken and just needs adjustment... or is there even any adjustment up there at the headset?
I did replace all the cables about 8 months ago so it shouldn't be a lubrication issue but I'll pull it out and re-lube it while I have the headset open.

The photo may show it pointing up, but that's not how it attaches. You turn it so it points down and through the pump arm from the top.

Also, if your rod doesn't look like the one in that photo -- if it actually is just an "L" -- it's not the right part.

I'll take a closer look at it in the daylight.
Thanks again!

Dear Sirs,

I have the same problem as the original poster.how can I bend the hook so it enters the slide rod in a way that it doesn't idle too high?

Thanks

Kind regards

Jorge

Sort of confused here. What problem are you having like the original poster?

Are you losing throttle response?
Is your hook popping out?
Or is your bike just idling high?

The hook popped out at the beginning then I got a pair of pliers and bent the hook so it wouldn't pop out any more , however now it revs too high at idle and lowering the idle with the idle screw does nothing. How can I lower the idle?

Thanks

Kind Regards

Jorge Vidaurre

Anyone got any ideas?

It sounds like you may have bent the rod a little too much.
I would either try un-bending it just a bit or using the adjuster on the throttle cable to loosen up the cable and give it some slack.

Thanks for the reply aiosi. I tried unbending the hook however the idle still finds itself a bit high. Appreciate it, where could I find the throttle cable adjuster?

Kind Regards

Jorge

If you unhook the cable, does the idle drop to normal? Let's fix the right problem.

Follow the cable and if there is an adjuster, it will be at one end or the other. I think mine was on the outside of the airbox that hold the carb. If not, my cable had a little piece of brass tube soft-soldered to the cable. Stick a soldering iron it and it should loosen and slide to a more neutral place on the cable. Make sure it doesn't slide off as it could be a bastard to get back on.

Jerry

Throttle cable adjuster. Screw in to loosen. Make sure to loosen the nut first or you might break it.