I have a '97 F3, with about 32,xxx miles. The problem I am having is that when i flick the throttle a little bit (By a little bit i mean from 1200 to about 2200 RPMs),then back out, i am getting an odd vibrating noise. This is not the same noise as when the CCT fails. Its not the plastics, tank or windscreen. It only makes the noise quickly and does not persist after it occurs, but when i back out my idle speed drops and sputters suddenly, and feels like its about to stall. The idle speed does go back to normal (about 1200 RPM) after a minute or so, but if i flick the throttle again i get the same response. If i flick it a few times, the engine will stall. It happens even after the engine is warm, and does not matter if i am in neutral or in gear with the clutch pulled in. The sounds location seems to be under the tank. It just started doing this about 40 miles ago, and I am pretty worried about it :\.
Also, I have a MCCT installed, and when my bike started making this sound i re-adjusted it and the sound/problem still persisted. I have also pulled the petcock, and it was in working condition. Oil level is fine, ive changed about 1500 miles ago. Tested fuel pump and it was working fine as well.

My bike seems to be operating normally when at speed, and at low speeds (25-40 MPH) with no hesitation or any other issues. Starts fine when i use the choke and does not stall out after being started before I flick the throttle. Hopefully I have provided enough info. Anyone have any ideas?

Thanks!
-Phill

 

The problem has gotten worse, but it is a bit different then when it began. When i flick the throttle (in neutral or in gear with clutch engaged) from 1200 up to 5000 RPMs, I am getting significant staggering/cutting out in the 1200-2500 range. After it passes this, the engine seems to catch and rev through the RPM range normally. When i throttle up slowly i do not seem to encounter this stager. Also when idling at a light or revving the engine its coming a lot closer to stalling out. The lights all begin to dim like its about to die. It does recover after about 30 seconds of rough idling but as soon as i flick the throttle a little bit or stop at another light the same thing happens Ive also noticed that the exhaust is smelling a bit different then it usually does, but it smells more like oil then unburnt gas. That vibrating sound that i mentioned before is also still there.

Im thinking its possibly the valve clearence. Would explain the vibrating noise I mentioned previously.



Any ideas?

 

sounds like u have carb trouble. they could be outta sink or they need to be cleaned

 

sounds like you need a good carb clean and synchronize.
When your low speed (idle circuit) gets clogged there isn't enough fuel for the bike to idle well or rev up. But when you get to high RPM's it gets into the MAIN JET and revs up fine.
Your valves could also be too tight from not being adjusted.
is it harder to start cold?

 

It is a bit harder to start when cold then it used to be, but im encountering this when its warmed up as well. Im currently working through an electrical problem that could be tied into this. Is it possible my MCCT was to tight when installed?

 

MCCT as in a cam chain tensioner?
I suppose that could contribute to the problem if it were to tight.
What is your Idle set to?
on some honda's I've had if the idle was too low, when I revved them up it would sounds like a train chugging for a milisecond until it was past like 2,000 rpm. You should double check the Chain tensioner and set it to spec,

But it seems like your carbs are just dirty, especially when you say it will start with the choke. Get some seafoam and try to run it in your tank if you really don't want to tear into the carbs. good luck man

 

Yea I was referring to my manual cam chain tensioner. I have my idle set to a little over 1200RPM, and it normally fluctuates about +200RPM. I believe my recent rough/low idling ive been experiencing is due to an electrical issue that im working through (Its on another thread). I just was concerned about the lag when I flick the throttle, but im pretty conviced now that the carbs are dirty. I finally found another instance where this has happend and that was the problem. I pulled the tank when it first started happening and ran a third of a can of sea-foam directly through the vaccume system, didnt fix the problem but at has been 7 months since they have had a proper cleaning so it wont hurt to pull and clean them. Ill figure out that problem once I get my electrical issue ironed out. If that doesnt do the trick ill just have the valves/timing looked at, but im pretty convinced its not valve-related now.
Thanks for all the input!

 

An easy way to see if there is varnish in the carbs is to pull out the needle. If there is this brownish stuff built up on the needle, then you have a varnish issue. This would indicate that it is also in the passages of the carbs which probably would be easier to remove from the bike and clean. Taking the carbs off the bike and cleaning isn't hard at all. Putting them together is a little tricky, but not impossible. The hardest part is probably the syncing which really isn't all that bad.

 

There are prolly 100 guys out there (me included) that'd love to know your secret for getting the throttle cables back on

 

didnt read the other posts so sorry if this is repeat:

its a fuel problem. check fuel lines, clean carbs, fuel valves, idle mixture, etc.
should be easy fix