Mend > Motorcycles

adam bike doctor?

hi adam bd
thanks for your reply. sorry i am late getting back to you reasons beyond my control

db 125 cuts out at 50

i had a look at the needle in the carb it is on the third ring nearest to the point. the diaphram looks ok not worn or loose so i reassembled it all. and went for a ride. it still cut out when i try to force it over 55mph and while the bike is slowing down to about 40 if i dethrottle and throttle back up again the bike starts up and i carry on my way. could this be a way the manufacturer is using to limit the bike to 50mph.
i am thinking of getting another groove cut into the needle to see if it makes a difference.
thanks again

robin
August 2010

DB DB 125 Vehicles, Motorcycles Adam Bike Doctor

ok if you come off the throttle and back on again and the engine picks back up then i would say that it may have an accelerator pump type carb on it and its getting a shot of petrol when you open the throttle back up after closing it whcih richens it up briefly ..which points towards the bike running weak/lean so in theory another groove would be the right way to go but its not the answer the answer is to make the main jet a bit bigger or fit a bigger one i have a set of jet drills that i use they are very small and go right down to 0.02mm ! so for instance lets say your main jet is an 80 then try an 85 main jet.try this though ...look at the throttle cable where it goes onto the carb and see if there is a small arm that get pushed down when the throttle is opened it will be either black plastic or metal if it has this then its got an accelerator pump.also if you have the air filter off the back of the carb and open the throttle then you will see a suirt of fuel everytime you open the throttle up.

adam bike doctor
August 2010