Hi all,

Just purchased my first track bike which is a 1990 FZR 400 SP, hopefully going to be a regular on hear and hopefully learn a thing or two...

Absoloutly over the moon with the bike and cannot wait to go out on the track, but there is just one or two things that are bugging me slightly, i want the bike to be reliable yet perform and run well first problem;

Bike is running total loss and has had a full engine overhaul by NM Tuning with minor porting and has only done 1 track day by previous owner up until now. Bike runs lovely and is very crisp, however it is very very hard to set of without stalling, it is really hit and miss sometimes you can pull off (just about) using very high revs, but most of the time you keep the revs high, let the clutch out and she just dies. The previous owner has taken the complete airbox off so the carbs are running bare, he said that he was told to take it all off for racing as it had had minor porting. I am wondering if this has a part to play or could it be the pilot jets or carbs just need setting up?

Last problem is when the engine is off with the tank pulled back, the butterflys in all four carbs only quater open almost like they are jammed it's deffonatly nothing to do with the throttle, as i eliminated the cable by pulling the lever back on the carbs by hand and still the same... Could it have been set like this as a short term safety feature to allow the engine to break in?

Apart from that she is brilliant

Many thanks for taking the time out to read it is much appreciated...

Woddy

Because this is a track bike your not actually racing huh ?
Put an airbox on it, they need to have still air to work, while your at it you might need an airfilter ... they don't actually do a K+N but if you get a 1WG (600 3HE) you can stwist the top to make it shorter.

Welcome to the forum ... we like pictures

Many thanks for the reply, nope will just track it in the mean time then will race it when the season kicks off all being well...

Ok thanks well i will put the box back on and see how i get on, i supposse it's gotta be a step in the right direction!?

Just need to see why the butterfly's are not opening fully now...

When i have a minute i will take some pictures for you all to see!

Thanks
Woddy

If this is an sp model, then it will have a close ratio gearbox,this means that first gear will be a higher gear than standard ,so it will need more reves are needed to pull off,

hunter wrote:If this is an sp model, then it will have a close ratio gearbox,this means that first gear will be a higher gear than standard ,so it will need more reves are needed to pull off,

I think this, and the lack of airbox and (maybe) slightly wrong gearing will be the problem. Put the airbox back on

If it's running total loss then the lack of stator won't help with the stalling issue, as it reduces the flywheel mass.

mines doing about 72 and running like yours but is rr box. i have the airbox on but no filter in and it works well. i grease the underside of the tank by the entry and the top and inside of the box to try and keep larger bits out, not sure if it works but makes me feel better!
try upping the idle speed to about 3k, sounds a lot but when it's running on track you wont get below it anyway! should help the poor starting. let it warm up properly before you try moving. you do have to nail the throttle to get a good launch, and one other thing to consider is the sprocket gearing. try 14/45 or 14/44 for the sp box.
do the butterflies open when the bike is running? you can use a small bottle of fuel to try it with the tank off.

Thanks to everyone for the info much appreciated, i will deffonatly give it all a look at!!

Taggy wrote: do the butterflies open when the bike is running? you can use a small bottle of fuel to try it with the tank off.

Taggy thanks for the reply, they don't open fully with the bike turned off? I havn't had chance to try it while running yet... But i thought it didn't seem right either way as my spare set of carbs open fully flat. I know that the dash pots will not work without the bike running as they open/close of a type of vacum, so i am not getting confussed with them !

Many thanks

mmm, can you manually move them further than they open or are they 'locked' at the position they reach? i know the pull cable will stop but if you can maybe it's just some adjustment somewhere that needs doing?
is there anything different you can spot when you put the carbs sets together? maybe they have been knocked and something doesnt line up? could it have been done due to the lack of airbox in an attempt to lessen the amount of air? seems wierd!

All four seem to be locked in that position... Nothing noticable, but im sure if i took the carbs off and looked underneath that it would be something silly like you say maybe a screw or arm has bent out of line slightly

Will have a look when i am back from Stafford Show on Sun/Mon and will let you know how i get on...

Many thanks
Woddy