50cc four stroke scooter

I’m a 100% moped guy but my friend bought a scooter and it ran pretty good ( hard to start when sits along time) didn’t idle well but did run and move. Was told the valves needed to be adjusted so I did that for him but now it cranks but won’t start !!!!! Would adjusting the valves cause this ??? Also new battery, carb and it still is getting spark. Help !!!!!!

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Re: 50cc four stroke scooter

Did you adjust the valves correctly? Did you touch the timing at all? If it ran before you touched the valves but doesn't now I'd say you need to check the valves again

Re: 50cc four stroke scooter

Did you have the timing marks right and have you done a compression test? What brand is it?

Re: 50cc four stroke scooter

This Repair forum is not the OFF-TOPIC forum where this belongs. If as you say,yer a moped guy, you should post in the appropriate forum.

Re: 50cc four stroke scooter

Fly scooter. It’s been running ok just hard to start and didn’t like to idle. Was hearing valve lash noise

Re: 50cc four stroke scooter

Sorry just was in a rush since my buddy needed it back right away. I have over 8 mopeds ( old school)

Re: 50cc four stroke scooter

Moped Lar (OFMC) /

Did you adjust the valves with them being stone cold? You cannot adjust warm valves.

Re: 50cc four stroke scooter

Yes been sitting for two days. I’m going to take all the plastic back of and the side cover to make sure it’s top center.

Re: 50cc four stroke scooter

The diaphragm PETCOCK is not opening or leaking air and could be the vacuum line not getting enough suction to oped fuel petcock this happens on 99% of these scooters until you get hat straitened out you will kill batteries and starter motors...

Re: 50cc four stroke scooter

Yeah it has a new one alone with a new carburetor. I figured it out. I was a whole turn off when I did the adjustments. Rookie with scooters plus I’m a moped guy. If it doesn’t have pedals it’s not for me. Thanks for the help from everyone

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Re: 50cc four stroke scooter

Went out check it and yes I was one revaluation off. Still have good spark but still won’t start ? I have a new fuel pump on the tank but instead of pulsating fuel it’s just pouring out. Rapped it a few times still doing it. Disconnect the fuel line took the plug out and sprayed starting fluid right into the top end and out the plug in and still doesn’t fire. I’m lost. I work on mopeds all the times and never have issues

Re: 50cc four stroke scooter

Well thought I figured it out but still not starting. Seems to be good spark but did notice the fuel isn’t pulsating it’s just pouring in. Disconnect it took out the plug and sprayed starting fluid right into the head and it still doesn’t fire. Wtf like I said I hate dam scooters.

Re: 50cc four stroke scooter

Does the petcock have a Prime position ? That would allow steady flow .

Re: 50cc four stroke scooter

No petcock on this scooter. 2007 flyscooter 50cc four stroke. It ran ok ( just hard to start ) before adjusting the dam valves no my buddy is freakin out. Fuel pumps of the engine but did notice the fuel was constantly flowing now which it shouldn’t but disconnect it and sprayed starting fluid and still nothing. What the hell could of went wrong

Re: 50cc four stroke scooter

This style

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Re: 50cc four stroke scooter

So , the fuel valve is stuck open . Blow into the vacuum line that comes from the valve .

It might just be stuck or the oring or the diaphragm may be bad .

What's the compression reading ?

Re: 50cc four stroke scooter

Going to grab my buddies now to check. Just crazy because I drove it in and it’s been being used for the last month. Someone said maybe the valves are not seating now that I adjusted it ??

Re: 50cc four stroke scooter

True , IF you adjusted them too tight .

Re: 50cc four stroke scooter

Well the first time I did them I wasn’t at top dead center I was off one turn but did it right this time and did them .004. Compression should be around 120 I believe ? I’ll message you after I get that done. Just all crazy all this by adjusting two dam valves

Re: 50cc four stroke scooter

Not getting any compression at all !!!! Piston is moving. Wtf is going on.

Re: 50cc four stroke scooter

It has no compression at all now since I adjust the valves. Ran before and now nothing. I’ll check the valves again. Was told to shoot air down the spark plug hole and see where the air is coming from. I hate scooters

Re: 50cc four stroke scooter

Are you placing the flywheel at the fire mark with the cam lobes pointing away from the valves ?

Re: 50cc four stroke scooter

Adjust the valves at .008 instead of .004. sometimes the cam will somehow get a high spot on a lobe and it will act as a decompression valve.

Re: 50cc four stroke scooter

Fly wheel is at T and the two small holes and the bigger center is lined up like they say they should be. Also put 50 psi in the plug hole and don’t hear any leak. Rechecked the valves and both at .004 and the .005 doesn’t fit in.

Re: 50cc four stroke scooter

Then back to .004 or leave it

Re: 50cc four stroke scooter

Done this 3 times and still no compression???? Drove it in ??? Put air into spark plug hole and didn’t hear any leaks, have spark, ect. All I did was removed valve cover an adjusted them to .004 a .005 will not fit, 3 holes in the gear are lined up ect..... just puzzled that it ran pretty good ( hard to start ) scooter has 1200 miles when I drove it in and waited a day and did the work an now 0 psi has spark and even tried starting fluid in the spark plug hole

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Re: 50cc four stroke scooter

I’m just baffled !!!!! How could adjusting the valves do this ????

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Re: 50cc four stroke scooter

Try pulling the tranny oil fill plug and inserting air in the plug hole . If you hear hissing or such from the oil fill hole it's time for new rings , at least , no matter the mileage , as you have no idea what that motor went through prior .

On the same note , did you have the exhaust header and the intake disconnected when you blew air in the plug hole before ? If you didn't , you'd likely not hear anything .

And , of course , these tests should be done with the piston at TDC compression stroke .(edited)

Re: 50cc four stroke scooter

Was at top dead center and no didn’t take the intake off or the exhaust. Just weird that I drove the thing to my house and now all this. Was just hard to start and didn’t like to idle so I bought a new carburetor. Did hear some tapping too and I was told to do the valves which were very tight.

Re: 50cc four stroke scooter

> Brian Terrell Wrote:

> -------------------------------------------------------

> Was at top dead center and no didn’t take the intake off or the exhaust.

> Just weird that I drove the thing to my house and now all this. Was

> just hard to start and didn’t like to idle so I bought a new carburetor.

> Did hear some tapping too and I was told to do the valves which were

> very tight.

All that^ sounds like low compression and the tapping might just have been the last straw . Take a real compression test or better , do a leak test like I described above .

I'm thinking it's time for some top end work . More than just an adjustment that may have been way too late . There could easily be a brunt valve .

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