P150x Wet spark plug - occasionally stops sparking in city
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Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Tue Aug 21, 2018 3:14 am quote
Hello, my p150x is all stock with the si20/20 carb. Currently spark is always wet. From low rev to mid, slight purring/misfire but overall not an issue. The big issue is that the Vespa can stop on the road, and when I pull the plug, itís totally wet and sooted, and wonít spark, I would clean on the street and it would spark again. The spark plug is brand new, it did this 3 days ago, so I bought another brand new one hoping it would help but same problem. Spark plug is NGK B7HRS.
I was thinking that the spark plug is too cold and would get a B6? And see how that goes? What about getting the carb to spray less fuel on the plug? How to do this? Thanks
Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Tue Aug 21, 2018 4:19 am quote
Ok so I couldnít wait, first pic shows the NGK BR7HS plug, Black sooted and wet at the gas station, I bought a NGK B6HS (hotter and without the resistor) and after doing a ride home I pulled the plug out and shows in pic 2, looks perfect to me! Weíll see. Dry and brownish. So plugs do make a big difference it looks like. Drove great as well. Ok canít upload 2 pics at the same time, first shown is the previous one

D0B91994-23B2-484A-AF62-1D6570D5B685.jpeg

Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Tue Aug 21, 2018 4:20 am quote
Here is the B6HS plug

A7000646-4940-4D62-A17F-617650B4E328.jpeg

Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1668
Location: London UK
Tue Aug 21, 2018 10:28 am quote
Did the plug dry out because there is now no oil in the gearbox?
Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Tue Aug 21, 2018 10:35 am quote
Jack221 wrote:
Did the plug dry out because there is now no oil in the gearbox?
No no, that problem has been solved! I split the engine casing and changed the gear oil O-Ring.

When I did that job I also did the crucifix and installed a new spark plug that the store suggested which was not really good.
Molto Verboso
PX221 Malossi, O tuned PX200 and some motorbikes
Joined: 14 Jun 2017
Posts: 1668
Location: London UK
Tue Aug 21, 2018 11:02 am quote
Check the oil again. Make sure it is still there. Vespas have a habit of making it dissapear.
Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Tue Aug 21, 2018 11:07 am quote
Jack221 wrote:
Check the oil again. Make sure it is still there. Vespas have a habit of making it dissapear.
ok, good tip, will check that out.
Molto Verboso
Kymco AK550
Joined: 09 Feb 2008
Posts: 1139
Location: UK
Tue Aug 21, 2018 11:46 pm quote
From the pictures it is still wrong even with the hotter plug. Running rich could be carburettor flooding or air filter clogged up. If it is worse when idling then flooding is the most likely cause. Also check the cold start system, I don't know whether that is mechanical or automatic on this model.
Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Wed Aug 22, 2018 4:28 am quote
roadster wrote:
From the pictures it is still wrong even with the hotter plug. Running rich could be carburettor flooding or air filter clogged up. If it is worse when idling then flooding is the most likely cause. Also check the cold start system, I don't know whether that is mechanical or automatic on this model.
Thanks, the picture wasnít that great to see the electrode it was dry and nice and grey/brown. The wetness you see was from the thread from before. Scooter runs really well now, not sure for how long. The choke is manual and works well on cold start
Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Wed Feb 12, 2020 12:26 pm quote
I was googling for this problem, and I came across my own post about the same problem!

This has not been solved. Spark plug up to the thread wet. Wondering what this can be. I mention the thread is also wet because this can lead to other things, like piston rings? Once I clean the spark plug, all is well for a couple of days, then maybe a week later, problem again.
Ossessionato
73 Rally, 74 Rally, 76 ET3, 80 P200, 06 PX150, 65 Li225 Silver Special, 86,95,96 Elite 80s, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 3406
Location: Oceanside/ SF
Wed Feb 12, 2020 12:37 pm quote
Do you have a standard 20/20 carburetor with the correct jetting, or has it ever been messed with? Do you know what size jets are installed?

The same question goes for your exhaust. I read the motor is still a stock 150.

Last edited by MJRally on Wed Feb 12, 2020 12:43 pm; edited 1 time in total
Member
P150X
Joined: 21 Jul 2018
Posts: 11
Location: Greece
Wed Feb 12, 2020 12:41 pm quote
all is standard/stock
MJRally wrote:
Do you have a standard 20/20 carburetor with the correct jetting, or has it ever been messed with?

The same question goes for your motor and exhaust- still stock 150 or has it been modified?
Ossessionato
73 Rally, 74 Rally, 76 ET3, 80 P200, 06 PX150, 65 Li225 Silver Special, 86,95,96 Elite 80s, 2015 HD Road Glide Special, 2011 Ural Tourist
Joined: 18 Jan 2012
Posts: 3406
Location: Oceanside/ SF
Wed Feb 12, 2020 12:44 pm quote
I revised my post too late, you had already replied. Do you know what the jetting is set at in the carburetor? Are you comfortable opening up your carb and telling us what numbers are stamped into the jets?
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