Engine stalls after long ride

[johnson]

Went for a 300 mile run the other day.  About 60 miles into it I turned a sharp corner and the ps250 lost power and coasted to a halt.  Thought maybe vapor lock and loosened the gas cap.  That seemed to help although it did stall a few more times on the trip.  On the last leg it did better if I kept my speed around 60-65 mph.  Faster and I'd stall. 

Background:
I did try a tank of lower octane gas at the beginning of the trip.  Later filled up with 93 proof. 
It's a 2007 PS250.  I got it a few weeks ago with 526 miles on it. 
It has been cold so I tuned the carb a little rich.  (probably need to take it back down now)
I changed the oil and gear oil as soon as I got it. 
Has been running fine around town.  Speeds of no more than 50mph. 

Anyone had this happen or know of what might be causing the stalling?

[naughty lee]

It's possible that your mixture and tickover levels are not quite right.
Get the bike warm(take it on a five minute run)
The engine must be hot.
Get it home, clean and gap your plug. Refit the plug.
Fire it back up, set your tickover( idle speed ) to max
Turn the air screw half a turn left and wait a few seconds, listen to the engine.

Your aim is to give the correct amount of air.
When you have found the correct setting, the engine will rev higher.
Start with 1/2 turns, then fine tune with 1/4 turns
You want the engine to be revving as high as possible.

Once you have found the correct air setting, then turn the air screw 1/8 th of a turn towards rich (that's clockwise)
Then turn the idle (tickover) screw anti(counter) clockwise so that the engine speed comes back down to an acceptable tick over level.

Your mixture is now set. Your idle( tickover) speed is also done.
For some reason I turn my tickover down too low after doing this, then when it comes to cold starting it can stall.
Don't be too frugal with the idle speed!
You should not need to go near the air screw again now.

You might find also that you gain a little top end speed. Best of luck

[johnson]

Thanks for the info.  I'm new to working on scooters.  Does the 4T PS250 have an air screw?  I know where the idle screw is.  I think it controls the mixture.  Don't know the air screw location.

[naughty lee]

I've not seen your scoot, but if it has a carburettor then it will have an idle and an air screw. Normally ( but not always ) the idle screw is larger and higher up than the air screw. Do your research though before tweaking

[Vivo]

I think C.A.R.B. approved scoots have no air screw to pass emission standards.. they are factory set to be very lean...

[Punk052]

the mixture screw is on the driver side of the carb, My p250 has a hole in the side grill that lines up with the screw. I made a tool to adjust it out of some thin metal rod and just hammered the end into a flat head screw driver. Once you find it, keep notes on all the changes you make so you can go back if you need to. I would also suggest that after you get the mixture set up as you want it, put a small dab of silicon over the screw (I messed with mine and it vibrated out on the highway, had to buy a new one and the scoot was down for a week) you might also cheack your diaphragm on the top of the carb for holes or tears around the edges.

[hypophthalmus]

Can I skip setting the idle speed to max and leave it within spec, and still find the setting that gives the highest RPM?

[hypophthalmus]

Also, the manual says

Pilot screw opening 21⁄2 ± 1⁄2 for People 250; 11⁄4± 3⁄4 for People S 250. I assume that's number of turns away from fully closed?

Can you just go by that?

[naughty lee]

You could do.