2013 Movie 150 Dies when coming to a stop and will not restart

[Reycuda]

Hi Everyone!
I just got a Movie 150 that had been sitting for over a year.  I plugged in a new battery and the little scooter started right up and idled like a champ, but after some driving around (maybe 10 miles) the scooter now dies when coming to a stop and will sometimes restart, but it does not want to idle when I come to a stop.  When it does restart it will idle, but it dies when I give it some gas. I find it odd that it does want to idle when it finally starts, but dies when I give it gas to take off. It also sometimes just cranks and cranks, but no start. It has about 3600 miles and for the most part seems to have been taken care of.  Oil is clean, air filter looks new and the plug also looks great.
I have now drained the fuel and topped off with fresh fuel.  I took the carburetor apart to check the jets and float level, all checked good.  Jets were very clean, but I went ahead and dipped the carb for 4 hours in a bath of Berryman Chem-dip twice.  Fuel filter is not plugged and the float bowl has fuel when I have drained it a few times thinking I had bad gas.  I also checked the fuel pump by applying vacuum and it is working.
I am thinking that maybe the TPS needs to be adjusted or synced. My questions are,

1. Where is the mix screw and
2. How do I sync the throttle position sensor?

I appreciate anyone's advise on this nice little bike and what I should do as maintenance at this point.  It's 8 years old and has 3600 miles.

Thank you,
Rey

[Ruffus]

@Rey, pls see link
https://www.kymcoforum.com/index.php?topic=31833.msg223178#msg223178

then depends what kind of carb you have on your scoot.
Pilot screw is usually on the LH side horizontal or LH side from top down.

My suspicion would be, after cleaning the carb again and airblow all tubes, a leak in your vacuum hoses or a leaky intake flange. There is an O-ring which hardens sometimes.

Airfilter renewal or at least inspection. Sparkplug nenewal or checking.Sparkplug cap new?

But IMO, when the scoot already ran properly, it's mostly a fuel case. Take the fuel line off and check during cranking.

Maybe this link helps too
https://www.kymcoforum.com/index.php?topic=31762.msg222535#msg222535
Give us a feedback if possible.

[Iahawk]

not positive if this will work for your scoot but here's the tps reset instructions for my S200..

*tps reset - with key off, open throttle all the way.  turn on the key, wait 8-10 seconds.  slowly close the throttle and turn the key off

Ruffus gave you lots of good suggestions..but my 'go to' when I hear that it idles but dies when you give it gas is a clogged pilot jet. I have had to pull my pilot jet and clean it multiple times..I finally bought a few new replacements so I always have a clean backup. I don't put a lot of miles on my scoot.

[Reycuda]

I cannot figure out how to reduce the size of the picture so I can post, BUT I'll try the TPS reset provided Iahawk and see if I can get it to fire.
Numbers on the side of the carb are :

120723
102534

Kymco
Taiwan
8

Other side I see "LFB5"
Mixing screw is on the left side from top to bottom like Ruffus mentioned in his response.

Could this scooter also have a spark issue? Even though I checked for spark, could it be intermittent?

[Ruffus]

@Rey,
-pilot screw, consists of 4 parts
needlescrew itself/ spring coil/ little washer/ o-ring
IF this needlenose tip is demaged, no idle
IF no O-ring, no idle

All parts there, screw gentle full in, then 2 1/2 turns out for basic adjustment.
-pilot screw out to highest idle
-adjusting screw down to 1800 rpm
Testing leaks, spray brake cleaner around the carb and vacuum lines.

Yes, there could be a spark issue, take gloves and wiggle your sparkplug and cable.

I'm still.towards clogged carb, because I had the same on my GD 150 carb and could (despite hot ultra sound cleaning of the body/ everything dissambled) NOT fix it again, so I took an €41,-aftermarked KEIHIN carb and prob's solved.

[Reycuda]

In terms of the mixture screw, I do not have the correct D shaped driver for this in my kit of 10 special drivers for carburetors. The D shaped one I have is either to big or too small, but I will see what I can create.  If anyone has the information on the correct driver "D" for this carb?

Thank you Ruffus for the information.  Let me update you and see what you think. I really don't think the mixture screw is an issue at the moment.

I had a rough time this morning getting the scooter to start after the carb install.  Here is what I did.
I installed the carb and did a TPS sync with the information provided by Iahawk.  Turn the throttle all the way to WOT and then turn on ignition, wait 8-10 seconds and slowly close the throttle. then turn off ignition.
The scooter was a cranked and no start.  I took off air filter and sprayed some carb clean into the air tube behind carb. More cranking and no start.  I figured I better check for spark, so I took out the plug.  BTW - Air filter looks brand new and plug looks real good as well(new).
I found the plug was wet(fuel), so I cleaned it up and cranked the motor with the plug out to dry the cylinder.
We have spark, so I reinstalled the plug and tried again.
Crank, crank, crank oh no battery is not getting low.  Throw the charger on the battery, Battery is brand new and holds 12.6v, but I have been cranking a lot.
Finally the motor starts for a split seconds and dies.  A few more cranks and same, starts for a split sec and dies.  I tried to give it gas and nothing.  More cranking and finally the bike starts and I give it gas and she comes to life.  BTW – this happened about 10-15 times before she finally started.  Moving the throttle back and forward trying to keep bike alive as she misfires.  Finally she smooths out and sounds good.  Idles perfect and sounds strong when I give it gas.  I turn up the idle on the center stand and let the rear tire spin while holding 4-5k rpm. I leave the bike running for 15 mins.  I turn the idle back down to 1800-2k and everything is perfect for a minute or so at the most. 
Then the engine start to misfire again and then dies.  She starts right back up but now when at idle, the engine starts to misfire and die.  Starts back up, idles fine for a few seconds and then the engine starts to misfire again and die. Oh no, what’s going on here?  Now engine begins to act up even more and cranks but doesn’t start until I let go of the starter button.  Again she idles, but begins to misfire after a few seconds and dies unless I hold the throttle open to over 3k.  She is acting the exact same way before I removed the carburetor for a cleaning and drained the gas.  Please keep in mind that I didn’t find the carb to be dirty or plugged in anyway when I took it apart.
I purchased this bike recently with a dead battery and not running even though she started right back up after just a new battery.
During the time the scooter was running on the stand and the idle was good, I sprayed carb cleaner all around to see if I had a vacuum leak and I did not find any leak.
I have moved the spark plug cable around and nothing changes.
I moved the TPS wires and tugged on the sensor and I did notice some changes, but not significant.

What does the TPS information do in this case?
This bike is not fuel injected, is there an ECU?  I understand what a TPS does, as I work on all my cars.
What can be causing the misfire? lean misfire?

Why am I getting a misfire at idle, but not at high rpm?  I do not think it’s the idle jet honestly because it will idle on its own sometimes.

Maybe it has something to do with temperature as it seems that the idle issue gets worse as it warms up.
I am beginning to think that maybe this is why they stop riding it.
I have rebuilt numerous automotive carburetors over the years, Holley’s, Edelbrocks etc. I have taken and rebuilt a dozen scooter and motorcycle carburetors over the years.  I have never had any issues, even old tractors and an old model A Ford I had with an updraft carb.

So my problem now is a misfire at idle and hard to start. She seems to have lots of power if I hold the gas open and put a load on with the rear brake on the stand. Is this a lean misfire?  The bike seems like it could run all day at 6k rpm.

Sorry for the long write up and thank you for all your help in advance.
Which after market carb did you buy?  I am in the USA, by the way.

[CROSSBOLT]

Vacuum operated fuel cutoff valve not opening.

[Ruffus]

@Rey, pls see link for carb info...
https://www.kymcoforum.com/index.php?topic=31762.msg222535#msg222535

- one more suspect is your bystarter, it has an
 O-ring...demaged/NO idle
- bystarters quit service sometimes too, check on a battery, whether this piston comes out about 10mm, takes a few minutes and your bystart warms up
-don't dissasamble!

Did by chance anybody mess with valves? 0.12mm IN/EX cold

For the pilot screw a normal 6mm flat screwdriver should do.
Sparkplug black.or just wet or whitish?
Misfire usually means lean or ignition coil.

One more, but far shot:
-could it be somebody was into its stator?
'Cause there is a pickup sensor, which times your ignition point. Like I say, just guessing

Even you don't see a lump of gunk in your carb, can still be clogged.
Bought a "KEI*HIN" aftermarket at amazon.it
Cheap stuff, but works. Had the same trouble like you have now. Put SMALLER jets in it and worked.

But @CROSSBOLT might have a point too with the cutoff valve!?
.

[Reycuda]

Hi CROSSBOLT - I do not think this has a vacuum shut off valve as the gas tank is on the floor board and there is a vacuum operated fuel pump to bring the fuel up to my carb.  I have only seen the fuel cutoff's when the fuel tank is gravity feed (gas tank under rear seat). And the scooter will run all day at 6,000, but not idle when hot.

I will check the bystarter, I was already thinking to mess with this because it only acts up when the bike warms up.  I can hold the throttle to 5000 rpm's all day and its fine, but once I start to have it down to an idle it stalls only when hot.  I rechecked the idle jet and its clean still. 

Ruffus I think you are on to something here.  By the way it runs better after I completely removed the air box tube at the back of the carburetor., letting more air in. (maybe to offset all the extra fuel from the bystarter not working).

Any suggestions where to get the correct bystarter?

BTW - My mix screw is not a flat blade type but a small D shaped.  I removed the small metal security cover, but I just do not have this exact size in my bag. I have used my d shaped drivers before on other scooters.


Thank you!

[Ruffus]

@Rey, first time I hear from pilot screws being capped on KYMCO carbs. According to # is this the original Kymco carb.
Had this many years ago on WEBER register carbs, but didn't see this for many years on scoots.
(just o be sure pls see pic)

Bystarter: before ordering any from AMAXON or other supply.
Check on which groove the bystarter is fixed with this semicircle clip/ keep a pic.
-take it out, put its cables on a 12V battery and after few minutes this piston should be out completely. The black plastic body gets pretty warm/ =normal.
-IF ok
-take a new/fitting (25x1,5mm in my case) O-ring, lubricate and fit.
-try not to harm this little nozzle, its spring coil attached and sensitive to bending
-unplug this TPS cables for testing

Another try:
-make an external fuel supply from a bottle and fuel line
-block unplugged vacuum lines with bolts or similar to make sure your vacuum system is out of business
-start with this gravity "bottle tank"
IF the carb is now adjustable, its in your vacuum lines or vacuum fuel pump

@jermwars, it's a carb not a golf- ball 😊

[Iahawk]

@Ruffus, hmmm, you have me thinking about how my bystarter is attached to my carb...I believe when I removed it this past Spring that the 'C' clip that holds it down lost one of the 2 mounting tabs so it is held down with only 1 screw...and I havent' looked at the condition of the O ring.

Could an improperly sealed down bystarter cause the rough running I've been experiencing all riding season?

Something I definitely need to investigate as I did break the mounting tab off before the riding season began..and I have had the rough running condition ever since...coincidence?

[Ruffus]

@hawk yes,
 IF  your bystarter is mounted a little bit tiltet, there is a fat chance of sucking air,  ruins air/fuel ratio and hence hard to idle. This O-ring slips up sometimes = air intrusion.
Bystarter not sealed properly/impossible to gain a normal idle. Way TOO rich fuel composition.

[CROSSBOLT]

You got me on the vacuum operated fuel valve! You are right! Low mounted tank + fuel pump = valve not required.

One of your descriptions "will fire when letting off the start button" may indicate low battery voltage during start sequence. Do you have a multimeter?

[Ruffus]

There is a link back in 2014 where @Yager200 had a similar problem, maybe some hint for us..
https://www.kymcoforum.com/index.php?topic=12666.msg126492#msg126492

[Reycuda]

Hello Gentlemen and thank you for all the responses. 
I think I may have found out something and this might help you out as well Iahawk, as I think the bystarter is the source of my issue.  Here is what I did.

Yesterday afternoon I started the bike and let it run and idle which it does fine when cold.
When it warmed up and started to misfire and die at idle, I reved it to 5-6K rpm and verified that the bike runs fine at high rpm.  I did several times and the bike begin to run worse and worse especially at low rpm (under 3k).  I purposely wanted it to be acting up so I can check the bystarter circuit.  Everything checked out with the bystarter circuit, even the needle had extended out about  4-5mm.  Still not trusting the bystarter operation, I removed the bystarter completely off the carb and used my thumb to cover the open of where the bystarter mounted. What do we have here..........I restarted the scooter and .................. it started to idle at 1800. WHAT......?
With my thumb covering the bystarter opening (bystarter sitting on the ground) the bike runs perfect.  Idle at 1800, revs to 9k all on the stand, I can turn off the scooter and restarted like it was running on fuel injection.
So for now, I have ordered a new bystarter that I will install, maybe mine is leak and not sealing completely (not sure).  The unit will be here tomorrow for about $25.00 USD from Amazon.  I will report back when I install the new one.  The o-ring on my old bystarter is intact, but it does look like it has shrunk over the years.  When I sprayed carb cleaner over this area I did not get a change in rpm.  Maybe the needle is not sealing completely?

CROSSBOLT - I have over 12v when cracking, so I think that is good.

Ruffus - my Carb has the mix screw positioned differently than the pic you provided.  Mine can be adjust from the top, while your picture shows one adjust from the side.  My mixture screw is a D shaped and was capped.  I'll try to see if I can somehow get a picture up.

Thank you all.  I think we are all learning something new everyday.