scooter hard to start By wizardaeon (Read 1,901 times)

[wizardaeon]

assuming that my spark is just right
assuming that my carburetor is adjusted correctly
assuming that my valve lash is set right

what else would cause low compression

50 cc scooter

139qmb engine
longbo 2008

[sprocket]

The first two 'assumings' don't cause low compression.. the third one could...

or you have

Worn rings, cracked piston, scored cylinder wall, bent valve/s, burned valves, cracked head etc, etc

None of these are good...

Why do you think your compression is low? have you tested it?

[Alleyoop]

If you do not have a gauge, talke the spark plug out and put your finger in the hole nice and snuge and crank the engine. If it blows your finger off you have descent compression, if you just feel a little pressure then your compression is low.
Alleyoop

[scooter]

I have a 150-06 that has 1700 miles/kilometers on it and it is impossable to start could it be the valve lash and if so what should the clearance be----2008 model year -150-06

[Alleyoop]

Scooter,
Adjust your valves to TOP INTAKE VALVE TO .004" and BOTTOM VALVE TO .005".

Once it starts and warms up does it start easier?
Does it run good after it is warmed up?
Does it Die or want to Die when you come to a Stop or Does it come down and IDLE just fine?
If the hard starting just happens only when it is COLD I would suspect the Enricher(CHOKE) not working
Alleyoop

[sprocket]

With 1700 miles on it is is certainly overdue for a valve adjustment. I would start there as Alley suggests and if that doesn't fix the problem then consider the choke...

At least you know that it is something other than the valves....

[scooter]

Thank you for the responses;;;; 1,,once it starts and warms up it runs fine and starts fine.I can shut it off and do my errands,up to 1/2 hour and it will still start good.2 It runs fine when it is warm..3 once it is warm it idles fine and when you come to a stop it idles down like it should.. One other thing I noticed my top speed used to be about 57-58 now it is only 54-55..I use sta-bul. the blue marine type for the ethynol gas that we have

[Alleyoop]

The tight valves will cause it to loose some power due to loosing some compression so take care of adjusting the valves first. Take your time adjusting them and do it right and it will run much better.
Alleyoop