So I recently had my carbs tuned, and other work done to my new bike, an '89 CBR600. I was hoping just a sync would work out the flat spot between 4200 and 5000 RPM. It did not. So now I am at a stage where I could either take the carbs apart giving it a good clean, or getting a dynojet stage 1 jet kit. I was hoping for some opinions here. I am running with a K&N intake and SuperTrap exhaust. Any ideas would be great. Thanks.

 

Yup, Jet that stuff up!

 

Turn of events today on the way home from work.

Sitting at a stop light with the clutch pulled in just chilling, all of a sudden the idle dipped down well below 1k RPMs. I started watching it and a few seconds later it did it again. I gave it a little throttle and it almost died on me! I'm wondering if this is the infamous fuel pump problem or if it is another symptom of the carbs?

 

could be either. if your fuel pump is shagged, it may account for a flow problem affecting a flat spot too.
wait, 89? isnt that diaphragm fed? check the vacuum line for cracks in it.

also cleaning your carbs properly should help somewhat, take them somewhere that has an ultrasonic cleaner

 

Thanks tiger. I'll check the lines before I take it in. And I don't know about the diaphragm... so maybe? I'm sure I can find an answer at my local independent. But any info I get here is less time wasted in the shop!

I thought it might be the fuel pump because I've heard multiple times from multiple people that they are an issue for the 'canes.

 

With the bike running, turn your fuel petcock off, after a few seconds, you should hear the fuel pump clicking like a mother f'er, if it does not, you have an issue in the pump circuit.

 

How about if when I first turn the key on, it starts to tick for a few seconds?

 

Well thats a good indication that it is working properly, but if you do what I mentioned above youre guarenteed to know it works. There is definetly a shortage of fuel somewhere, my opinion, first clean the carbs really well, second pull your sparkplugs and look at the colour of the electrode see if youre not getting enough fuel, or if youre getting too much. Third, ensure the wires on your coils are tight, and ensure the connectors in the harness under your tank are clean and it wont hurt to put a dab of di-electric grease on them. LOL Now im getting into overkill to find an idle problem.

In a nutshell, start where the fuel originates. SO Ensure fuel petcock filter is clean (Drain the tank first before you take it out), Verify fuel pump works, ensure inline fuel filter is clean, clean carbs ensuring fuel needle filters are clean, after that move onto spark issues, verify your battery is charging at 13-14V while bike is running, verify all connections, check sparkplugs, ect ect

 

Plugs, battery/charging system, and connections are all good at this point. Fuel filter is new and clean. I'll check out the carbs and the pump this weekend along with the petcock filter. Thanks for all the great the advise! Very, very much appreciated! Now if you could only send me someone to buy the old fairings, you'd be a god! Hahaha.