sluggish when warmed up.

[sylvaner01]

Hey guys, so glad to be on this forum finally.

I have a 1991 FZR250 3LN and the <a class="inlineAdmedialink" href="#">bike</a> runs pretty well (for a while)

I rebuilt the carbs on her last week and then again this week because it was running a bit sluggish.

My bike runs fantastic when I give her 5 mins to warm up, I run it around the suburbs for about 20 mins occasionally reeving to about 12k+ but never over 13k...

as soon as it gets a little warm (after 20-30 mins or running) it sounds really flat through the exhaust and completely lacks power, power is cut by about 80%, I can rev over 10k to get my power back but as soon as the throttle is let go the engine backfires heaps and sounds terrible

I pull over and it stalls straight away. I wait about 30 seconds and it starts up straight away and runs like new again.

Can anybody give me a hand in figuring out the issue? I am happy to get my hands dirty if thats the case =D

Thanks in advanced. Jack

[sylvaner01]

okay, so today I changed the oil, played around with the exup settings and also disassembled the exup. I am missing the spring in the exup system shown here: http://www.cartestsoftware.com/fz1/imag ... ance04.jpg
I hardly think this is any cause to my issue though.

I looked in the fuel tank and found that there was surface rust, could this be blocking the fuel from entering the carbies when the engine is warm?

I am thinking about replacing all the spark plugs, I read somewhere that this could magically fix the problem i am receiving.

I am having the issue of hot starts, when the motor has been running for 30 mins, I kill it.. wait an hour, then try to start it again. I have to have it on half throttle to get any idle at all and cannot rev the engine at all.

when I let go of the throttle the bike just dies and the same continues.

I have received a suggestion to disable the exup altogether which I plan to do tomorrow, I thought atleast cleaning the system would make it work better, however the problems still exist.

Thanks for any suggestions guys.

[sylvaner01]

so today I checked the voltage, 12v when off and around 13.8-14v when on so all that seems to be fine.

I took out the fuel filter and found out it was installed backwards.. oh shit I just realized I didn't clean it before I reversed it.. oh well
The fuel pump is making a clicking sort of noise when switched on, I wonder if it is having trouble picking fuel up..
Not a hell of a lot of fuel is in the fuel filter, it is only half full.. would this be something to watch out for? not enough fuel pressure perhaps?

I took the air filter out and cleaned the hell out of it, hopefully the bike will be somewhat different.

then to take my anger out on the whole situation I went down to some local block of land and did a massive muddy burnout =D