erratic idle cutting out on deacceleration

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johnny650
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Tue Jul 04, 2017 8:28 pm

My Li150 S3 has been starting and running superbly all year until last week it developed a peculiar fault out of the blue.

On my way to the Dentist late as usual and every time I cut the throttle in traffic the engine just spluttered and cut out.
The last mile or two was stop start traffic so i needed to keep about 1500rpm or it just cut out .its very embarrasing to have to kick start the scoot every 10 yards or so for a mile let me tell you.

At every other throttle position the thing pulled like a train without a hicup splutter or anything and it started on the button first kick.

Anyway today I finaly got around to getting to the bottom of it and guess what I found ????? ;)

Picture to come

Chris in Margate
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Tue Jul 04, 2017 10:27 pm

Pilot jet fallen out.
Receipt from the fuel stop dropped in tank and jammed in the carb.

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Timbo
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Wed Jul 05, 2017 7:18 am

Obviously not stator then.... :?

Martin20
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Wed Jul 05, 2017 9:37 am

Please don't keep us in suspense for too long as I have been suffering the same on my LIS 150! I have stripped and cleaned carb more times than I care to remember, with no success. Changed pilot jet from a 45 to a 48, on Monday, played about with mixture screw, and adjusted throttle position, and at the moment, it seems to be OK, but I am not 100%confident!

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HxPaul
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Wed Jul 05, 2017 9:40 am

The fuel cap air vent was blocked.

johnny650
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Wed Jul 05, 2017 10:05 am

Chris in Margate wrote:.
Receipt from the fuel stop dropped in tank and jammed in the carb.
dayum ....how you get that so quik Chris ? :lol: :lol:
Timbo wrote:Obviously not stator then.... :?
Obviously .... ;) :D

johnny650
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Wed Jul 05, 2017 10:20 am

Martin20 wrote:Please don't keep us in suspense for too long as I have been suffering the same on my LIS 150! I have stripped and cleaned carb more times than I care to remember, with no success. Changed pilot jet from a 45 to a 48, on Monday, played about with mixture screw, and adjusted throttle position, and at the moment, it seems to be OK, but I am not 100%confident!
sorry martin I've been having trouble finding a image host thats working to post a picture. :cry:
Photobucket have committed Hari kari and dumped on all their loyal customers .

Ok the answer is its an air leak on the inlet somewhere ....excess air at idle .

Throttle response at all other throttle positions is perfect and unaffected so it has to be due to the idle components ie air, pilot jet and slide .

I removed the hose and filter in preparation for removing and stripping the carb for cleaning and inspection and immediately saw this huge split/tear in the back of the rubber hose.

So with the normal settings there is way too much air available in proportion to the fuel at idle so the mixture went very lean and cut out . At all other throttle positions the mixture was also too lean but ironically that actually makes the engine perform slightly better ......right up to the point it seizes up :lol: Image[/photobuckvid]

johnny650
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Posts: 398
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Wed Jul 05, 2017 10:24 am

Martin20 wrote:Please don't keep us in suspense for too long as I have been suffering the same on my LIS 150! I have stripped and cleaned carb more times than I care to remember, with no success. Changed pilot jet from a 45 to a 48, on Monday, played about with mixture screw, and adjusted throttle position, and at the moment, it seems to be OK, but I am not 100%confident!
sorry martin I've been having trouble finding a image host thats working to post a picture. :cry:
Photobucket have committed Hari kari and dumped on all their loyal customers .

Ok the answer is its an air leak on the inlet somewhere ....excess air at idle .

Throttle response at all other throttle positions is perfect and unaffected so it has to be due to the idle components ie air, pilot jet and slide .

I removed the hose and filter in preparation for removing and stripping the carb for cleaning and inspection and immediately saw this huge split/tear in the back of the rubber hose.

So with the normal settings there is way too much air available in proportion to the fuel at idle so the mixture went very lean and cut out . At all other throttle positions the mixture was also too lean but ironically that actually makes the engine perform slightly better ......right up to the point it seizes up :lol:
Apologies for the double post but not my fault.
Not sure what is happening but aspects of scooterotica posting are not working properly. :roll:
frequent blank screens on submitting posts and double posts etc.

johnny650
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Wed Jul 05, 2017 10:28 am

HxPaul wrote:The fuel cap air vent was blocked.
nice guess paul but the engine functions normally at all other throttle positions ;)

Mr G in NYC
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Wed Jul 05, 2017 1:44 pm

Try using IMGUR as a photo host . much easier than photo f@@k it !! LOL G.

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