Weak spark By pretendentas22 (Read 4,046 times)

[rob63]

Sept 16, 2012 11:10:03 GMT -6 pretendentas22 said:

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.

All he means is make sure the cam is in the right position when checking the valve gap (which I suspect you`ve done anyway).
The rather crude pic below gives an idea, always get the cam so that a part of the red area is near the rocker arm, that way no pressure is on the rocker arm.

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[pretendentas22]

Hi, thanks for explain. Yes you are right I did the clearance when the cam sprocket is aligned. I don't thing the problems are in clearance.

[pretendentas22]

Hi again,
Short update. I was checking valves' clearance when heard strange noise. When piston reaches TDC I can hear the sound which reminds air blows. Is it normal or I do have compression leakage?

[Alleyoop]

Alright, lets back up here, JUST check your compression if you do NOT have a compression gauge do the following:
Take the Spark Plug out stick your finger in the hole and nice and snuge HOLD THE THROTTLE WIDE OPEN AND CRANK the motor over. If it Blows your finger out of the hole you have descent compression. If you just feel some pressure on your finger then you have a COMPRESSION problem. Now to test if its the RINGS or LEAKY VALVES pour a teaspoon of OIL down the plug hole and AGAIN STICK YOUR FINGER in and HOLD THE THROTTLE WIDE OPEN and crank it and see if it makes a difference in the compression.
Get back on the test.
Alleyoop

[felliott]

If you hear it in the area of the camshaft when you turn the engine over a small hiss is normal

[pretendentas22]

Yes, it was in camshaft area.
I tried to test compression by finger and it was blown out. Any more ideas?
Basically I have spark, compression, fuel, air, valves clearance is done and it still doesn't start.

[Alleyoop]

Good that your compression is descent and it should run.

If you squirt a little bit of gas JUST a little down the intake does it ATTEMPT to fire or does it fire and die?
Alleyoop

[pretendentas22]

put petrol not even single attempt to fire.
I am not sure is it important, but all my attempts I took off the head to check for crack. Pulled the valves and checked all head. No cracks. After I put the head back and cranked the engine it started. It worked while I rev, but just left on idle and it stalled. After again the same old story - not a single attempt to fire. It looks like this bike is just doomed.
Is it possible to check timing?

[Alleyoop]

GO look at your first post and you will see just about where the timeing mark should be on the flywheel when you align the Cam Sprocket correctly.
Alleyoop
www.scooterdoc.proboards.com/index.cgi?board=150cc&action=display&thread=6724&page=1

[pretendentas22]

I remember this one, but what I am thinking maybe my trigger started to delay the impulse. Thing is scoot worked before. Of course with misfires in certain intervals:)