Stalls in idle, especially if choke is off

JoshWED · Post by **JoshWED** » Fri Aug 20, 2010 4:45 am

OK...here we go with the first real issue. The first couple days of Stella were no problem. Took her around town for a good few hours.

Today on the ride home from work she kept on stalling. At lights especially, but even sometimes when I pulled the clutch in and was slowing down to stop from 2nd or 3rd.

I adjusted the idle screw by 1 turn..which made the engine idle super fast...but this got her home. Even with some stalls.

Once home, I tried various settings of the idle screw, but could never get her to just stay idling. The best luck I've had is by keeping the choke on; when the choke is all the way out, she'll run w/o stalling while in neutral. Close the choke, and the engine will idle a little bit faster before stalling out.

As the engine cuts out, if I give her just a tiny bit of gas, it sounds like the engine floods and cuts out. If I give a 1/2 throttle or so, the engine will rev before stalling.

Should I try the fuel mixture screw? Or does it sound more like a fouled jet. The previous owner just cleaned out the carb (the scoot had been sitting for a bit, so they cleaned the carb and replaced battery it seems). I'm guessing i'll end up trying both.

one other issue: sometimes the kickstart seems to stick (like too much pressure needed to turn over the engine...then a jiggle and it works fine)

JoshWED · Post by **JoshWED** » Fri Aug 20, 2010 12:15 pm

Update:

I checked the idle jet...clean. So is the filter. However, the spark plug looks black...so I'm thinking it's running rich. Problem is that the fuel mixture screw looks plastic...and stripped. But looks like you could use a 12 of 15mm on there...anyone ever had to do that?

Runs ok on about 1/3 choke.

JoshWED · Post by **JoshWED** » Fri Aug 20, 2010 1:27 pm

Update 3 (can you tell i'm a n00b?)

still concerned about the fuel mix, but got the stella running and idling nicely. adjusted the idle a lot till I found something that seemed like it worked. this morning, i rode it with the choke at 1/3 for a while...until it began to want to die while idling. then pushed the choke in and it was fine for the rest of the ride.

was surprised that I had the choke open for so long...maybe 5-8 minutes. it's in the 90s here at the heat of the day, 80's in the morning. so didn't think the engine would be so cold.

illnoise · Post by **illnoise** » Fri Aug 20, 2010 2:57 pm

On a hot day, it is a bit surprising you'd need the choke that long. The idle screw is plastic? (I don't know stellas, only vespas). The idle screw (NOT the throttle screw) should generally be about 1.5 turns (3 half-turns) out, so if you're *way* off that, you're probably overcompensating for something else.

Sounds like you know as much about carbs as I do… if the jets aren't clogged, it could still be a passageway, if you still have problems remove/disassemble the carb (loosen the bolts back and forth a little at a time, or you can warp the base!) and soak it in carb cleaner then blow out the passages with compressed air. Seems like new carbs get gunked up all the time, maybe dust/gunk from manufacturing or sitting around until they're sold.

Shane Wilson · Post by **Shane Wilson** » Fri Aug 20, 2010 3:55 pm

It really sounds like you've got some dirty jets. There are two stacks to look at when cleaning the jets. The idle jet and the main stack next to it. Looking at the color of a plug tells you mostly nothing unless you do a proper plug chop. The idle screw is the one sticking out of the top of the carb box. It adjusts the idle speed of the engine. The MIXTURE screw is on the back of the carb and is behind a white plastic screw plug (unless that plug was removed and discarded long ago like mine). The mixture screw controls the mixture of air and fuel. I highly recommend that you not tamper with the mixture screw unless you're doing proper plug chops.

To check the color of you plug properly go for a ride to get the engine warmed up. Then get up to third gear. While having the engine at the top of its revs for a bit, pull in the clutch and kill the engine and pull over to the side of the road. Remove your plug and have a look at the color. You're looking for something in the mocha range but a light tan is a-okay.

You bought the bike used am I correct? Chances are it sat for a while and there may be some funk in the tank that has made it to your jets. I doubt very seriously that after running fine for a couple of days that suddenly your mixture is out of whack so I'd chase down the dirty jets/carb ideas before tinkering with carb adjustment.

loodieboy · Post by **loodieboy** » Fri Aug 20, 2010 6:45 pm

I agree with Shane, start with conservative treatment. Clean the jets and get some new gas in the tank. A splash of sea foam wouldn't hurt. While you're at it, drop in a new properly gapped spark plug Unless the previous owner monkeyed around with the air/fuel mix, I'd leave it be. As to the kick start, I don't have a clue.

lmyers · Post by **lmyers** » Fri Aug 20, 2010 7:59 pm

This will sound very simple, but my 04 was doing the same random stuff until I replaced the spark plug cap. It was a bit loose, I guess.

loodieboy · Post by **loodieboy** » Fri Aug 20, 2010 8:18 pm

Oh, good call lmyers. Doesn't the cap simply screw onto the terminal lead? If so, it may just need to be snugged up.

JoshWED · Post by **JoshWED** » Fri Aug 20, 2010 8:45 pm

picking up a new plug tomorrow...will report back. Thanks for the help all!

JoshWED · Post by **JoshWED** » Fri Aug 27, 2010 1:30 am

As an update...scoot has been running well for the past few days. I decided that much of my problem was from engine flooding. So now I'm sure to shut off the petcock after each ride, no matter how short (probably need a needle, but don't feel like doing that yet!) I even let it run a bit after the fuel is off.

Have been kicking to start it lately, as the battery seems a bit weak--guess it could also be the starter who knows! But kicking it is more bad-ass anyways.

Finally, changed out the spark plug boot for an NGK boot. The stock boot's brass clip inside the boot was loose and a pain in the ass.

illnoise · Post by **illnoise** » Fri Aug 27, 2010 2:11 am

replacing the needle is cheap and fairly easy. but I'd turn off the gas when parked anyway.

Bb.

Shane Wilson · Post by **Shane Wilson** » Fri Aug 27, 2010 4:05 pm

Did you ever plug chop after your carb tinkering?

I still advise that, regardless of how well she appears to be running.

jmer1234 · Post by **jmer1234** » Fri Aug 27, 2010 4:06 pm

I am still waiting for the 4t, but have gone in and man handled plenty of 2ts at my local dealer during this tribulation. One thing I noticed is the fuel petcock is very stiff to turn on the scooters I have had access to, and does not strike me as very sturdy. Has anyone had problems with this piece breaking, especially if it is being turned after every ride?