Can someone explain the 4500 rpm surging and how to fix it?

I was out riding yesterday after I changed my front sprocket (down one tooth) and adjusted the chain and noticed a surging at about 4500 rpm. My bike is in excellent condition and only has about 5500 miles on it. Only a weekend rider. I only put non-ethanol fuel in it and it runs fine. It idles well, smoothly and pulls really strong. The problem is it surges at that 4500 +/- rpm range when I am just cruising through town or on a flat stretch trying to maintain 35 mph or so. It also happens when I start to crest a hill while trying to maintain a constant speed. At first I thought the chain was too loose but I rechecked it and it is per the manual (about 1 inch up and down while on the center stand). 1 inch is about right in the middle of the specification.

I am wondering what exactly is causing the surging problem and how it can be fixed. I would like to avoid having to put a $300 computer control box thing on it if I can. I read some threads talking about a "PCV". To me, that is a "Positive Crankcase Ventilation" but I don't think that is what it is here on this forum.

I need a little education on what is going wrong and any suggestions on what to do. It is a little annoying.
 
PCV = Power Commander V
Sounds abnormal. If you haven't already try putting your original sprocket in to verify it still happens. I think its coincidence timing wise.
 
Did the surge happen before you changed parts or just after?

You may just need a tune, which would be either an ecu flash, or an installation of a PCV to get dyno tuned. Typically this is the case o fix the powerband which gets hurt by EPA emissions regulations.
 
I was out riding yesterday after I changed my front sprocket (down one tooth) and adjusted the chain and noticed a surging at about 4500 rpm. My bike is in excellent condition and only has about 5500 miles on it. Only a weekend rider. I only put non-ethanol fuel in it and it runs fine. It idles well, smoothly and pulls really strong. The problem is it surges at that 4500 +/- rpm range when I am just cruising through town or on a flat stretch trying to maintain 35 mph or so. It also happens when I start to crest a hill while trying to maintain a constant speed. At first I thought the chain was too loose but I rechecked it and it is per the manual (about 1 inch up and down while on the center stand). 1 inch is about right in the middle of the specification.

I am wondering what exactly is causing the surging problem and how it can be fixed. I would like to avoid having to put a $300 computer control box thing on it if I can. I read some threads talking about a "PCV". To me, that is a "Positive Crankcase Ventilation" but I don't think that is what it is here on this forum.

I need a little education on what is going wrong and any suggestions on what to do. It is a little annoying.
Power Commander Five Dynojet product
 
I have recently filled is with 100 octane non-ethanol just to see if there was a problem with the fuel. Well, it still does the surging described above.

What do you all think? Would the PCV fix this issue? Is that the only option?
 
I am looking into the TPS and mine shows 16 at the low end and 93 at the top end. I think for the electronic stuff, coils and those things, I may need to take it to the shop as electronics are not my thing.

You mentioned fuel. Does this bike have a fuel filter in it? Where is it located and can it be changed?
 
I am looking into the TPS and mine shows 16 at the low end and 93 at the top end. I think for the electronic stuff, coils and those things, I may need to take it to the shop as electronics are not my thing.

You mentioned fuel. Does this bike have a fuel filter in it? Where is it located and can it be changed?
TPS sounds normal. Mine is 16 on the low and 97 at the top end. Yes, there is a fuel filter. Yes, the fuel filter can be changed. This thread gives a great description with pictures - https://www.998cc.org/threads/gen-2-how-to-clean-fuel-filter.22359/
 
This fired some neurons from a similar problem I had.
I second the coil check - I had two fail on my 2007 @ 36k mi, and replaced all four. I had spent an excessive amount of time trying to diagnose the issue (I'm not that bright), and finally just replaced them. Problem solved, for at least the ensuing 36k.
 
When you have a bad coil or coils, it makes your bike act very strangely. To the point where you will usually check many other areas before coming to the conclusion that it is your coil. The rev range would depend on which coil is bad. Mine stuttered under 2000rpm. I have heard of others with a bad coil say they did not notice anything wrong until 5000rpm. I have heard some also say nothing crazy happened until 7000rpm. You could also check for error codes. There could be one stored in the dash.
 
Was the ECU tuned for the -1 up front?
Vcyclenut in Seattle can flash the ECU. Get 4 new, Yamaha coils (about $85 each), new plugs, get rid of the AIS. You can stay with regular gas, or he can add more timing that requires premium 92 and above octane.
Tell vcyclenut exact mods. for the flash. Never change anything without reflash, which is free at vcyclenut. Best $200 you'll ever spend.
Use care if you're not a mechanic. Seen perfectly good bikes ruined junk by folks who don't know wtf they're doing . Usually starts with "it was running fine, then I did xyz I read online..."
Yamaha retarded timing in 1rst, 2nd, and third gear below 5000 rpm on these bike so folks wouldn't wheelie and kill themselves on the FZ1, which they considered an old mans bike...proper flazh fixes the factory detuning among other things, exup, etc. No need for a PCV.
 
I got a "Healtech" speedo fix for the -1 on the front to calibrate the speedo. I remember that the sputtering happened before the -1 sprocket change also.
 
The speedometer correction did absolutly nothing for your fuel map!
Oh, I know it didn’t do anything to the fuel map. I just stated it to make note that the bike was sputtering before and after the -1. Who knows, you may be spot on and Maybe a coil is going bad. I just hate throwing out 4 coils just to see.
 
You have pulled the plugs, they look good? Bike runs great with no stumbles except the 4500 area up to red line?

Surges all gears 4500? no difference being in a higher gear running slow.
 
Haven’t pulled the plugs yet but it does stumble in all gears. The rpm is always the same. I didn’t pull the spark plugs because the bike only has maybe 6000 miles on it and I think you are supposed to change the spark plugs at around 20,000 miles if I’m right? So that’s why I didn’t pull spark plugs. Above 4500 RPM all the way to redline it runs clean and pulls very strong, no stumbling at all.
 
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