Lean surge?

firefly

firefly

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Now I have the 2004 FZ1 for almost a month, I get this surge starting at 1500RPM, no matter what I do it jumps up from 1500 to 4000RPM, the problem is worse when cold but still remains to a lesser extent when operating temperature is reached, even when the bike is in neutral I can't get a steady 3000RPM its either 1500 or 4000RPM.
the bike is bone stock, had 4800 miles on it when I bought it. I didn't check the TPS yet, could an out of spec TPS cause that?
I am trying to get a feel for the bike before doing any mods, I will not drill holes and enlarge holes in the carbs so that is out of the question, unless a simple reversible needle change will correct this problem.

another problem is when I start the bike from overnight cold with choke it keeps jumping from 1200 RPM to 4000 RPM for two seconds & moving the choke lever doesn't seem to have much control its either 1200RPM or 4000RPM?
Any suggestions or help is greatly appreciated.
Thanks
 
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stupid question...is it just the tach jumping or the engine is surging? the tach will move to certain increments for trouble codes, and 4000rpm being a bad speed sensor/connection for example
 
ptrudel said:
stupid question...is it just the tach jumping or the engine is surging? the tach will move to certain increments for trouble codes, and 4000rpm being a bad speed sensor/connection for example
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when the engine surges the tachometer also jumps up, I see no codes.
 
If the engine is surging it's something more than a fault code...have the carbs been cleaned/sync'd since coming out of storage? Has it always done this surging since you've gotten the bike a month ago or is it a new problem?
 
ptrudel said:
If the engine is surging it's something more than a fault code...have the carbs been cleaned/sync'd since coming out of storage? Has it always done this surging since you've gotten the bike a month ago or is it a new problem?
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its been doing that since I bought it a month ago, I am not sure if it was stored or not used, I plan on carb synchronizing and TPS adjustment, in the mean time I am using carb cleaner additive something similar to seafoam.
I am trying to avoid removing the carbs and cleaning them, such a headache on that bike.
thanks & keep it coming.
 
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Trying not to be a Dxxxk, but maybe you should sync and do the TPS before trying to trouble shoot the problem.

Also, ther is no substitute for sea foam...IMHO.
 
85vmax said:
Trying not to be a Dxxxk, but maybe you should sync and do the TPS before trying to trouble shoot the problem.

Also, ther is no substitute for sea foam...IMHO.
Click to expand...

Out of sync carbs don't cause surging, I never had a bike with TPS so I'll try this first but whenever I decide to do it I realize the gas tank is full:))
 
I had a lean surge at part throtle when I bought mine. I installed a thin washer under each of the needles in the slides and haven't had a problem since. richens the mixture a little at part throttle just off idle.
 
Update: I took the advice & used seafoam 4oz/ tank full twice, it did help a little then I did he TPS adjustment per Pat's instructions, it was set at 10K RPM I set it now at 5K RPM the surge is much less now but the carbs sure need synchronization, I don't think they where ever synchronized on this bike before, the off idle throttle response is better but not as crisp as it should be.
I think the surge is from clogged off idle circuit rather than too lean A/F setting of mixture screws.
 
Doing some work on the lights I measured the voltage across the battery with bike off it was 12.2 volts, started the bike with headlights on low, voltage at idle = 11.6 volts, this means the battery is being drained :(, at 3500 RPM voltage was 13.2 still not great to fully charge the battery, with headlights unplugged voltage = 13.6 at 3500 RPM & remained unchanged when I turned on the LED day light running lights ( they consume 24 watts total.) they are even brighter than the headlight in day time. power consumption was reduced from 110 watts for both headlights to 24 watts for the LED running lights with headlights off.
I noticed the surge I had diminished greatly & the hesitation at very small throttle opening is gone.
 
Hey this could simply be because of the ignition timing advance. Timing advance usually begins around 1500-2000 rpm. I wouldn't worry about it, lean surging happens at almost any rpm, most easily felt when your at a constant throttle opening. It will not cause a noticeable difference in rpm lean surging is something that you will only feel. Hopefully that answers your questions.
 
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