Post by stijnie on Sept 6, 2019 15:35:50 GMT -5
Hi All,
I busy with a chinese scooter 2 stroke TGB bullet BM1.
Since the beginning i have some problems to keep the engine running in idle speed.
After some checkups & changings, i can't get that motor in a normal idle speed.
I have also an other bullet and runs fine. cold , warm , no issues.
Problem:
Cold start:
Engine starts directly without any hesitation. turns 10 seconds and dies.
I need to pull throttle to keep the engine going.
when finally warm engine runs at 2000 rpm ( quite high) if I turn the screw of idle speed the engine drops directly from 2000 to 1200rpm. There is nothing between. Also when motor is really warm idle speed is 2000rpm and after playing with the throttle, motor drops again to 1200 -1500rpm and should come up again after few seconds to 2000rpm. and could drop again to 1200-1500rpm
Automatic choke has +/- 8VAC in idle speed.
battery voltage +/- 13 - 13,5VDC while running
Warm start:
When engine is off for 5 minutes and starts again , i need to throtle again en keep throttle up otherwise the engine dies again on idle speed after few seconds and throttle on 100% and come to idle , motor will keep turning at fluctuation 2000rpm -1500-2000 - 1500 rpm.
i was thinking false air intake.
I changed:
oilseals at crankshaft
cleaned carburator 2 X normal with compressor and 1x ultrasone.
swapped carburators but seems nothing changes.
checked reed valve and seems ok , replaced it with liquid sealkit.
sprayed with break cleaner on the carburator but not really found something. rpm drops a bit but can't find anything.
swapped air filters also tried running without air filters.
All remains the same.
I changed needle position, nothing changes.
changed seal on top of the caburator where the spring is situated.
adjusted the airscrew on carburator on a hot motor while running on idle speed of 1500rpm and came the the highest idle speed and lowered the idle speed. but then when cold starting the scooter is idle way too low.
No leaks somewhere.
HELP , i'm out of thoughts 
