Hi there i'm Mark,
i have owned a 1989 fzr 400 exup 3en2 for around a year now, however since taking delivery of it i have stripped the fairing and other none essential items to give it a cleanup, which is ok, however now it will not run(it did when i got it). It runs to a point then starts to get rough and trying to use the throttle "it just dies". I have now replaced the spark plugs, air filter, oil filter, fresh oil, fuel filter, fuel lines, i've had the garbs off and found that the diaphragms were not seated correctly and cleaned out the carbs with carb cleaner and an air line then the mixture screw were wound out then back in then 3 turns out. To no avail still will not run as it shouild. ( it runs really rich and when you can get the revs up it pops and bangs and fires out tonns of black smoke. CAN ANYONE HELP PLEASE!!!!!!!??????????

Mark

I live in the York area if there is anyone close to have a look. Cheers

2.5 turns on the mixture screws. Can you start it using carb cleaner, lift the slides spray it in, no choke, then see if it catches quicker

Does the exup open / close when the ignition is turned on ? Check the cables haven't frayed and the two tongue on the pulley are returning to the small hole at the front. The adjustment won't stop the bike running.

After this is the valves tolerances needing to be set up but usually that causes bad starting.

Have you had any jets out for cleaning ?

The main and starter jet are easy to transpose...... it may be that they are swapped over and the engine is unable to reach the point where the main jet comes into operation .
When this has occurred it is usually the case where it starts easily but wont rev above about 5/6 k but you might not be getting to that stage.


Check what size jets you have in and post back.
The only other thing that should make it as rich as that is the chokes aren't returning or the floats are too high /or the FLOAT needles are not sealing and you are flooding it that way.

I am too far away to have a gander.

Did this happen BEFORE you dismantled the carbs or did it just not start and then you took the carbs to pieces and found it runs too rich after cleaning ?

Hi guy s thanks for a quick response. I have reset the the mixture screws to 2.5 turns now and it starts fine, just needed to get the fuel through. The bike ran totally fine when I got it home. I had only stripped the carbs down as a last resort after doing other things first like the spark plugs, fuel lines, oil filter and air filter.I have just replaced the carb rubber mounts to the engine which has improved the tick over I think.
After stripping the carbs and rebuilding, they perform exactly the same as they previously did before I started doing anything. I am really struggling to understand why it was fine then the next it will not run. As I say it ticks over fine but when the throttle opens it dies or sputters like mad.

Thanks for all continued help with this issue
Mark

is the airbox sealed to the carbs properly ? run the engine and spray some carb cleaner under the airbox ... any change in revs shows a leak.
Start it with the choke in or out ? ... if it starts from cold with no choke then the mixture is over rich.
When the bikes running ... cover the part of the airbox snorkel - the snorkel inlet should face backwards.

ok .right the bike will not run cold or hot without the chock fully out. if i cover the snorckle it stops the engine when i manage to start the engine again it revs when normally it stuggles. same as when i have the air box off, with engine running i cover each carb air port in chick succsession (cant spell) then the trottle works lovely for about 10 second then goes back to stuggling. Further to this it Will not start with out choke if hot. Any advice is good advice all the time.

bumrush wrote:. I am really struggling to understand why it was fine then the next it will not run.


Mark

The reason is because modern fuel contain so much ethanol that it condenses very rapidly in the carbs and blocks the fuel jets.
If the bike is stood in damp conditions the extremely small air jets and passages also suffer blockages from corrosion/scale.

Cheap supermarket fuel accentuates this.

These bikes should be started and run up to temperature at least monthly.....preferably fortnightly.
Fuel and air through the carbs is the way to prevent blockages.... and clean filters.
I wont buy anything but Shell V Power now.( much less ethanol.)

Thanks willandrip i will be sorting this out very soon, i understand now why suppermarket s are so cheap. Anything else please would be appreciated. just need to get it sorted so i can ride the ruddy thing...

cheers again