hi. last summer my bike was running fine it would easily go over 120 mph...until my bike got stolen then once i got it back it wouldn't go over 90 mph. what could be the problem? please help. I got a 99 zx-6r with 23k...thanks

 

Drain the carbs & put some fresh gas in. Also Check your air filter.

 

i drained the carbs and it looked like clean gas drained out of them... I wonder if my airfilter might be missing, because the person that stole it also took some parts that i had to replace. Maybe he took the airfilter too. Will the bike even run it the airfilter was not in? I'll have to check that tommorrow but until then what do you think. thanks.

 

Oh it will run, for about as long as it takes to get some big debris in there to chew the engine up...

 

hmm, a thorough inspection is in order.

 

Yep, I agree with Dragone. Make sure that nothing got sucked in the airbox or restricting it. Definitely install an air filter. It is possible that the bike is running too lean without the air filter. Also check your throttle linkage to see if it's openning fully and not restricted. One guy told me he had problems because there was a popsickle stick stuck inside his carburetor intake port, so check everything thoroughly. Take off the carb and look down the intake ports. What condition is your exhaust in. Is it stock? Could be a restriction there too.

 

i got a full muzzy exhaust on it. but when i got it back i had to replace the can because he did some damage to the can. Another thing that i noticed is that.....before i got my bike stolen the bike ran slugish going into first gear and strong in the other gears. Then when i got it back the problem was reversed. now the first gear is strong and the 6th gear is slugish. I dont think the bike is redlining or winding outwhen it starts to hit 90 the rpm is around 7 or 8 when it starts to feel weak. thanks[/align]

 

they might have put 87 octane in the tank and drove it and now it aint running right.drain ALL of the fuel and put some premium in there.

 

i would think something is messed with your air intake, probably filter, considering at those rpm's at a lower speed nothing happens then it can rule out a fuel issue pretty much

 

Was the bike dropped on the RH side? if so, the timing pickup coilmaybe damaged and it's giving a false signal (caused by vibration) to the ECU that you're redlining and cutting off ignition. You need to check out the cables & linkage at the carbs and put the air filter back in, then tell us if it made a difference or not.