Poor starting moped

[Farmingstock]

I have a 4T Piaggio Zip 50cc that will eventually start but takes forever.

Changed the plug (spark is fine)
Checked the valves (.10 and .15)
Changed the choke to manual
Charged battery fully
Changed the fuel
Checked the fuel pump (fine to the carb)
Cleaned the carb

The bike will start eventually and starts fine once it’s started but once left overnight or for long periods it takes forever to start and you get the feeling it isn’t going to start.

Any suggestions?

[A100man]

compression check?
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Now: A100, GT250A, XJ598, FZ750

Then: Fizz, RS200, KL250, XJ550, Laverda Alpina, XJ600, FZS600

[Farmingstock]

[sickpup]

[Farmingstock]

Had another look today and can’t test the compression without taking the engine out, there is bearly enough room to get a socket on the end of the plug!

[that_impulse_guy]

it does sound like you need to investigate "changed the choke to manual" a bit more.

there is nothing that changes the starting procedure between hot and cold, besides the choke. Going over what you said, power is fine, hot starting is fine..restarting is fine.

so check out choke a bit. If you changed it to manual was it because you had good information that the automatic choke wasnt working? etc etc...go over that part of your thinking and redo if you find error in the logic. You perhaps have more info now, than when you did this specific mod that may contradict an earlier finding.

as a far flung "hey but what if it isnt the choke coz Ive checked it 100 times" then assuming all else what you said is true there is nothing else to check.
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Gone: Yamaha DT50lc, Suzuki DR500, Suzuki A100, Kawasaki z250ltd, RD350YPVS, Suzuki DR Big, Kawasaki AR125, Kawasaki KMX200, Suzuki GS1000S, Katana 1100, GS550M, Suzuki RGV250
Now: Suzuki GSX400X, Suzuki RF900R, NS400R

[Ayrton]

Sounds daft but have you checked the air filter? I spent ages trying to figure out why my scooter wouldn't start and a new filter fixed it The old one just became too blocked up even though it didn't look too bad.

[Farmingstock]

Took the air filter off completely and put my hand over the end of the carb where the air filter would connect and the bike starts much better. Any idea of what the problem could be and how I can fix it?

[sickpup]

The auto choke is broken.

[Farmingstock]

[jeffyjeff]

[Farmingstock]

[jeffyjeff]

OK. Then is it possible that you have an intake vacuum controlled fuel valve with gravity fuel feed to the carburetor? If so, the problem could be the vacuum valve, but odds are that you have a leak in the line between the vacuum valve and the carburetor. You can test by disconnecting the vacuum tube from the carburetor, tape over the nipple on the carb, and apply vacuum to the tube as you crank the motor over.

Your fix might be an inexpensive piece of vacuum tubing.
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History shows again and again how nature points out the folly of men - BOC

[Farmingstock]

[that_impulse_guy]

i admire whats going on, but when you consider the original post says the bike starts fine when its hot then you're left wondering if a vacuum fuel tap not getting vacuum can actually be the problem.
____________________
Gone: Yamaha DT50lc, Suzuki DR500, Suzuki A100, Kawasaki z250ltd, RD350YPVS, Suzuki DR Big, Kawasaki AR125, Kawasaki KMX200, Suzuki GS1000S, Katana 1100, GS550M, Suzuki RGV250
Now: Suzuki GSX400X, Suzuki RF900R, NS400R

[bugeye_bob]

[Farmingstock]

I have tried fuel directly to the carb and its still no better!

When I said in the first post it starts fine when warm, I should have been more specific:

When the bike has been left for any period of time over 30 minutes or so, it will turnover for 20 seconds and not start, with no matter what I do with the throttle on/off/ then all of a sudden it will start after turning it over and over, then once started, I can turn it off instantly (not warm) and it will start fine over and over again until left for a while!

However!

If I take the air filter intake off cover the carb with my fingers and turn it over (fingers wet with fuel) it will start better!

It won’t start with kick start at all until it’s been started with electric start, then it’ll kickstart everytime!

I have checked the autochoke, tried a manual choke, sprayed carb clean around the carb to check for air leaks, checked the vacuum and fuel pipe for leaks, checked the valve clearance, replaced the spark plug and air filter!

Once the bike starts it rides absolutely fine.

Hopefully that clears everything up! But the problem still remains

[Easy-X]

Going back to what jeffyjeff said: the "choke" on the carb isn't a choke, it's a fuel enchricher...

If you can start it with a manual choke - i.e. your hand over the intake - then either the pilot circuit or fuel enricher or both are not doing their job properly: it's a carb problem.
____________________
Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Farmingstock]

[Easy-X]

What sort of air filter system does the bike have? Bone stock or something aftermarket?
____________________
Royal Enfield Continental GT 535, Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[Farmingstock]

[jaffa90]

Have you checked the carb fuel level ?
On very old bikes they had a tickler to raise the level for easier starting from cold and on some newish lawnmowers they have a rubber pressure plunger to pressure the float lower to raise the level with no choke system.
I take it that you are not using the throttle on a cold start with auto choke!

[Farmingstock]

[jeffyjeff]

The odd thing is that the symptoms do not appear to be temperature dependent, and fuel flow to the carburetor is apparently unrestricted. Thinking about it, the carb float bowl should have enough fuel to start the engine and run it for about a minute just on the fuel in the bowl. It behaves almost as if the bowl has run dry and the engine needs to crank for a short period to allow the vacuum valve to pass fuel to the carburetor. Of course, without a leak, it is unlikely that is happening.

Maybe the float bowl has some debris in it that displace some of the volume in the bowl...perhaps from running poor quality fuel. Or possibly the float level is set too low. Or maybe there is a piece of crud lodged between the float and the needle valve, causing the needle to seat when the fuel is at an abnormally low level.
Just some suggestions of things to check. BTW, does the engine oil smell of fuel?
____________________
History shows again and again how nature points out the folly of men - BOC

[Farmingstock]

Not had chance to take the carb off again to check the float bowl again, but there is no fuel smell in the oil, it takes 21 seconds of turning over no throttle to start! I videoed it just to know how long! But then after that it’ll start instantly