Bike is only firing with choke up !

lilchunkyboy

Member
May 12, 2021
38
7
8
19
i have a 80cc 2 stroke. I ride it regularly. just after riding it, i went inside for a few hours and came out to start it. It only fires with the choke up, as soon as flick it down its just cranking and not firing, when i give it the throttle with the choke down it changes tone quite a bit but doesnt fire . I was first drawn to a carb problem,i checked for spark with placing it on head,and it sparked. The carb was clean, i blew through each jet,and theres nothing obstructing. I changed the spark plug, wire, and soldered connections, could it be spark ? too much resistance,e.g it fires outside, but not inside. i cant get my head around it, within a few hours it can develop a problem like this, fires quite nice with the choke up. ANY SOLUTIONS ?
 

lilchunkyboy

Member
May 12, 2021
38
7
8
19
i ensured the carb and the manifold were tight, where the exhaust mounts, theres a small gap due to the frame,not sure that it matters. i recently took the head off, ensured that the head bolts are tightened down.
 

Testname111

Active Member
May 20, 2021
127
41
28
To much oil in you're gas, dump some from tank and line, add more gas......I use 50/50 mix synthetic car oil and vegetable oil
 

Testname111

Active Member
May 20, 2021
127
41
28
If all fails with the carb try new electrical system from bikeberry.com super magneto and stage 1 cdi ( the cheap China ones suck and China cdi)