Hi I am talking about an 04 blue tank model bike that I have had for 12yrs so it is not new to me. I am reasonably ok with practical stuff rebuilt engines etc . So my problem started when I came to take thebike out after a longish 1yr year of no activity. Starts up fine ticks over fine will rev up if throttle is opened slowly but if throttle is opened fast then the bike coughs and splutters as though it is starved of fuel or over fuelling. carb stripped down and rebuilt several times, new standard jets, and needle, new diaphragm set up, new float valve, fuel height ok, so basically new carb bits all round. Still the problem exists. I have tried the needle in all 5 positions with both 137 and 147 jets and still the problem is present. Starts up and ticks over fine and revs up when twisted slowly. If throttle is twisted rapidly then the engine seems to be either starved of fuel or over rich and bogging down. Plug colour is dark so seems to be running rich. any ideas folks Ive had the carb on/ff so many times and run out of ideas. Ive even checked the connecting rubber to the engine for cracks air leaks( this would cause weak running but Im desperate helllpp. cheers rog p.
I assume there are no mods to allow freeflow of air to airbox! Otherwise this can result in tuning issues for you at the various stages of throttle opening - idle, 1/4, 1/2, 3/4 and full.
Mine will start idle and rev up slowly with no issue, stock bike, new pump and gaskets, if I take off it starts to rev then just burrrrrr like someone has hit the key, if I throttle back straight away it recovers to idle....everything is clean and free.....
Hi I had exactly the same problem as you. I've done everything you did and what's been suggested, however I also cleaned the air filter and changed the spark plug. Running sweet now.
Hi to all thanks for the advice given I could not solve the problem so sent the whole carb to a chap in Athens ( I am in Crete) His name is Byron and he is a carb guru. he fully stripped an d cleaned mine , made a small brass bush for the fuel pump rod to slide in without wobbling about and also altered the fuel pump lever mech to make it more efficient. He set all up as per standard . Put it on the bike and bingo bango puuurfect. So thanks for all the help and good riding to all.
Hi have you checked the fine fuel filter behind the needle float valve assembly? it is not shown on many diagrams of the carb, It usually allows low throttle ok but as soon as you want to use more fuel it restricts the flow.
