Weak spark By pretendentas22 (Read 4,023 times)

[pretendentas22]

Hello All,
I do have problem with weak spark on my GY6 125cc. I tested alternator which gives 37 AC volts, which is below recommended. Then I tested resistance. Charging coil gives 300 ohms, trigger 150. Both are in standard value. My question would be: is it possible to have correct resistance and the charge below standard value at the same time?
Plus, week ago I was able to start it just it didn't work on idle, but no problems on high rev. I was able to ride miles as long as I don't let it stall on the idle. Now it even doesn't start, just burps and nothing

[Alleyoop]

The symptoms you describe points to your valves they are tight and once they get really hot you loose compression and it will not hold low rpms and die.
Alleyoop

[pretendentas22]

OK, I will check valves clearance. What about stator, do I need to replace it?

[Alleyoop]

I see no problem with your stator, your scoot starts runs good is charging good lights and everything works etc.. I believe it is just your valves that are tight.
Alleyoop

[pretendentas22]

Thanks,
Is it possible the valves constantly stretches and stays stretched? Thing is I adjusted them three times within 200 miles and now it will be forth.

[Alleyoop]

NO, but then the question is did you adjust them correctly and at TDC and at what gap setting did you set them to.
If you already adjusted them 3 times it tells me your not adjusting them correctly.
Alleyoop

[pretendentas22]

Problem is my cam sprocket doesn't align at TDC. When cam sprocket is aligned piston is just about to reach TDC. I do my clearance when sprocket is aligned. The gap I set is 0.08 Did I miss something?

[jct842]

.08 is a bit much.

[rob63]

Sept 13, 2012 18:24:02 GMT -6 pretendentas22 said:

The gap I set is 0.08 Did I miss something?

Set them to 4 thou or 0.10 in metric.

[pretendentas22]

Hi again,
I just readjusted clearance, made 0.1 mm. No change, still doesn't want to start. Any ideas?

[rob63]

So in summary, original post was 'scoot not running', the scoot used to run but didn`t like to idle but ran ok at high revs ?
You`ve reset the valve clearances, can you confirm that you`ve removed the plug from the head and rested it against some metal, and cranked the engine to make sure you have a spark ?
If you have a spark then maybe it`s time to look at the carb. Are all the hoses in the correct place and in good condition ie: not split ? If you take the fuel feed pipe off the carb and crank the engine do you get fuel feeding from the pipe ?
If there is fuel feed then is the carb set correctly ? Locate the mixture screw and wind it in counting the number of turns until it stops, this is normally about 2 and a half or thereabouts. If all this is correct then you may need to take the carb off, remove the float bowl, remove the primary and main jets and make sure they are clear.

[pretendentas22]

Yes, it ran ok on high rev and didn't like idle. Carb is checked and cleaned, mixture is set 2.5 turn. Fuel gets into engine as I can smell it and spark plug is wet. Problem is I get spark but it doesn't look solid and thick. I measured stator volts, 37 AC, then I tested resistance. Charging coil gives 300 ohms, trigger 150 ohms. I am out of ideas.

[sprocket]

Check your engine ground, spark plug, plug boot, hi tension wire , ignition coil, CDI..somewhere there may be the problem

[tvnacman]

Sept 15, 2012 14:52:21 GMT -6 sprocket said:

Check your engine ground, spark plug, plug boot, hi tension wire , ignition coil, CDI..somewhere there may be the problem

Chris , your slipping . What ever happened to sprockets rollover procdure ?

For get about TDC get the cam lobe off the valve and set the gap then do the other valve same way . Roll the engine over a few times and recheck .

Valves need to be adusted when you first get your scooter , then every thousand they need to be checked , adjusted if needed .

John

[pretendentas22]

Hi, what do you mean get the lobe off? Do I need to take the cam sprocket away? My scooter has around 29000 and just recheck the clearance and it is 0.1.