bike stalls with too much throttle

[lykan]

hi
ive jst finished restoring a 89 etz 125 everything runs fine untill i fully open the throttle.
i can rev it to top of revs but soon as i twist the throttle grip more than a inch it dies if i release it will drop back to idle.
i cant figure it out
help please im dying to ride this bike!
cheers andy

[DAVID THOMPSON]

if the bike has points did you change then..
if they are old the spring may be weak
i had a bmw that would start and run fine till it went over 4000 rpm
the points looked fine and clean
changed them and bike ran ok
bike had been stored 18 years
also the capacitor may need to be replaced if its old
dave

[lykan]

hi david i have changed the points and condenser to no avail also checked the timing and that is spot on
i really have run out of ideas

[DAVID THOMPSON]

check the rubber boot where cable goes in the top of the carb
if its leaking air could be the problem at speed
makes carb go lean

[djsbriscoe]

What position is the needle set to? Try lowering or raising it on the clip to see if this improves things.

David.

[lykan]

tried the needle on all settings makes no difference the rubber boot on throrrle cable is fine
too ive changed spark plug ht lead and coil too

[beckyman]

Just had the same problem on my Puch MS50D. Solved - hooray - by removing and thoroughly cleaning the fuel tap. Enough fuel had been passing for low throttle openings but not enough to allow for the greater amount of fuel needed for wider throttle settings. Also check out Fuel cap for proper venting. Air must be freely allowed entry to the tank to replace the exiting fuel otherwise restricted fuel flow will inevitably result. Good luck.