TGB A-kros starting issue

[Vroom]

Hi All , thanks for letting me join your forum.

I recently picked up a non running Australian delivered TGB Akros 50cc as a bit of a project , there are no model designations i can see anywhere else but it definitly has a 49cc motor.

problem is it wont start - I am reasonably mechanically minded and i have done a site search but not found any answers.

engine has compression and is sucking fuel into the cylinder ok so i dont think its a mechanical problem. Engine will kick over on both the kick starter and the electric starter. I have tried squirting starter fluid into the carby to replicate fuel.

engine has spark , a fat blue spark.

so it seems like all will be good but still no joy ,not even trying to start.

i have been suspecting the CDI unit , my question is there any chance somehow that the CDI unit is faulty in such a way to deliver the spark at the wrong time?

[Vroom]

I should add its a 2004 model , australian delivered , and it does have some kind of factory fitted alarm system but i still get spark with the alarm system unplugged so i dont think thats my problem

[harry]

as a dealer we were instructed to remove alarms, that was in '06 i think
 so that might be one issue  or it could be that your not holding in the rear brake lever
when trying to start?
try holding in one lever at a time both front and rear... there is a electrical lock out
that shorts the CDI.. the switch may need replacing

BTW: do you have the alarm fob?

 oilyhans

[Vroom]

Hi Hans ,
thanks for replying , the engine does have spark and will turn over ( at a good cranking speed ) both on the push button and on the kick starter. It still has spark with the alarm unplugged , and i have the fob , tried replacing its battery but still no good.

there is one wire which shorts out the CDI and stops the spark but ive left that unplugged so there is spark all the time.

its a wierd one , ive never had an engine which had fuel , compression and spark but still wont run???

Hence my theory, and only a theory , that somehow the CDI is delivering the spark too late , past TDC so therefore engine wont run.

with an analog multimeter im going to try and look for the AC pulse from the pickup coil , to see if it arrives at TDC . If it does then i'll try replacing the CDI with a generic one .

[harry]

even if the spark was late it would back fire or some other indication that
the fuel was ignited.

has anybody removed the piston?
 if so its possible they put it in back wards  180 degrees
then the intake/exhaust ports don't line up

then there is compression if its too low ; nada, nothing, won't run
,
oilyhans

[Vroom]

ok , i did a proper compression test today , and it was down to 50psi so definitly a compression issue. Felt ok at first. so I removed the piston and found chipping and scoring not visible from above.
Im not going to repair the bike as it has some broken plastics and other issues so i will dismantle it and advertise parts for sale cheap to other members on this site.

thank you again for your help
John

[harry]

i'd suggest you put a 70cc kit on it and sell it.
 it will sell faster and replacement is easy will take about 3.5 hrs

 oilyhans