This is gonna be kinda long but I want to be as thorough as I can:

My 2001 will no longer rev past 6.5k RPM:
- even when I have it at WOT; it just won't go any higher; 80mph is the fastest I can go on the highway in 6th (top speed is not my biggest concern here, rather it's having the power to get out of harms way or pass other vehicles which I don't have when I can't rev past 6.5k...)
- in all gears except 1st where I can get it to go to 7-7.5 RPM
- The inability of the bike to exceed 6.5k RPM occurs whether I give a gradual acceleration at the throttle or crack it open fast, though cracking it open seems to cause the bike to bog at an even lower RPM than 6.5k (like around 4.5 - 5.5k) than when I'm more gentle with it

     This issue, which sounds like fuel starvation, coincides with the installation of a Bob Broussard ignitions advancer and a K&N drop-in w/restrictor. Before the K&N drop-in, I had a Uni-filter drop-in that had no restrictor. So, as I don't believe either of these two modifications play into my current problem, the problem does coincide w/these changes, so I'm stating them here.
     The bike has not been run much in the past several months but was riding just fine when I did ride her. The problems only started after the installation of the advancer and the new air filter. I do have some 'Sea-foam' running in the tank and there is possibly some residual 'Stabil' that I put in the tank early in Jan when I knew I would not be riding her much at the beginning of the year. Don't believe these should make much difference either.
     
What I've checked thus far:
- made sure the TM petcock's valve was fully open
- checked all the fuel lines for kinks, none found that I could see
- as is suggested in the numerous threads fuel starvation, I set the frame-mounted petcock to PRI but that only bought me *maybe* another 500RPM (that's hundred, not thousand) so the simple "just put it in prime and it'll work", well, didn't work
- checked the spark-plug gaps, they were in spec

Things I haven't done:
- taken apart the FM petcock and checked for tears in the diaphragm
- checked float height
- lots of other stuff that I'm hoping will be suggested here 

I've never had this problem before. Never. I've pulled her up to 100mph w/ absolutely no hesitation. Again, my bike is a 2001. As far as I know I have stock jets though I have not opened up the carbs to verify. The carbs were cleaned b4 I bought the bike last June (or so I was told). I have a stock exhaust. I just got done solving an electrical problem which before was solved I was starting the bike at the starter relay terminals w/a wire. After that was solved I was finally ready to start enjoying the girl but now I've encountered this issue and I've no confidence on the bike on roads where the speed limit is 50mph or more 

I've read about simplifying the fuel delivery system and I guess I can delve into that as a last measure. It just seems like there could be something simpler given that I could exploit the entire RPM range with the stock set-up before.   

Whew, if u got through all that and still care to offer advice, THANK YOU!! 

P.S. This problem sucks big a$$.

I never had such issues with my 2001 before or after my ignition advancer mod. I'd guess you're having coincidental problems.

Before you do any big projects to correct this issue, revert back to your original specs (uni filter, no advancer) and ride it to see if it eliminates the problem. If it does, reinstall one of the two changes you made, then the other, checking to see if problem returns. If it doesnt fix the problem then you know its unrelated to these changes.

My money's on the bike having sat and having stabil and sea-foam in it. You might just have to run a couple tanks of fuel through the system (ride it) and see if anything changes as well...

good luck!
pablo-

too rich top end, too lean ? dunno, without checking the plugs myself.

no, starvation is when the bike just stops running abruptly generally because the float bowls are emptied at higher speeds.

If PRI didn't eliminate the problem, it's not fuel starvation (at least not in the typical sense of a faulty petcock).

Are your valves in spec?

Quote from: pantablo on May 26, 2008, 01:32:08 AM

Before you do any big projects to correct this issue, revert back to your original specs (uni filter, no advancer) and ride it to see if it eliminates the problem. If it does, reinstall one of the two changes you made, then the other, checking to see if problem returns. If it doesnt fix the problem then you know its unrelated to these changes.

My money's on the bike having sat and having stabil and sea-foam in it. You might just have to run a couple tanks of fuel through the system (ride it) and see if anything changes as well...

good luck!
pablo-

Pablo, the only problem with this is that I can't undo the advancer mod. Well, I can but I'd need to send it back to Bob. But I will definitely try putting the Uni back in or just taking the restrictor off the K&N.
I really don't feel it's the stabil or sea-foam cause, well, the bike pretty consistently stops pulling at 6.5k. It won't go past that however much more throttle twist I give it. Wouldn't these two compounds affect the entire power range??

Quote from: ohgood on May 26, 2008, 05:04:09 AM
too rich top end, too lean ? dunno, without checking the plugs myself.

K, I'm going to take the restrictor off the K&N. I kept it on b/c my plugs gave the appearance that the bike was running lean. This is the easiest thing to change so I'll do this first.

Quote from: beRto on May 26, 2008, 08:05:48 AM
If PRI didn't eliminate the problem, it's not fuel starvation (at least not in the typical sense of a faulty petcock).

Are your valves in spec?

The PO said the valves were adjusted about 2-3 months before he sold it to me, which would've been about a year ago. I've only put about 1,500 miles on it since.

Quote from: El motociclista on May 26, 2008, 12:26:57 PM
The PO said the valves were adjusted about 2-3 months before he sold it to me, which would've been about a year ago. I've only put about 1,500 miles on it since.

I would recheck the valve clearances (unless you know the PO was a very capable mechanic). 

Quote from: beRto on May 26, 2008, 01:14:31 PM

Quote from: El motociclista on May 26, 2008, 12:26:57 PM
The PO said the valves were adjusted about 2-3 months before he sold it to me, which would've been about a year ago. I've only put about 1,500 miles on it since.

I would recheck the valve clearances (unless you know the PO was a very capable mechanic). 

No, it was done by a mechanic, not by the PO himself.

I'm inclined to think the throttle cable is out of adjustment or possibly the choke cable isn't letting the slides all the way in.

what about carb jetting?

I think you should listen to ben2go and check your cables. My throttle cables were too tight and it was really giving me problems. The choke cable hanging up could def mess with tbe bike. Of course having old gas in it with stabil and sea foam can't help the situation.

From my understanding Sta-bil doesn't keep the gas in it's usable form.It keeps it from breaking down into sludge and varnish.You know the dark powdery residue in your carbs.

Hey guys. Thanks for all your input and suggestions. It turns out it was simply the addition of the restrictor that was not allowing the bike to climb up into the higher RPM's. At the same time I put in Bob B. ignition advancer I swapped my Uni drop-in for a K&N drop-in and decided to leave the restrictor on b/c by the look of the plugs I looked to be running lean. The Uni that was in there had no restrictor. So, I presume as I was climbing in RPM's and the carbs were sucking in more gas not enough air was getting in and it was running way rich (due to the restrictor).

I am very surprised at what a significant difference a little restrictor makes in the air/fuel ratios and therefore the operation of the bike. I doubted it was the source of my problem simply b/c I didn't think it could effect the amount of air to such a degree. It's amazing. I literally would hit 6-6.5k and it could go no higher. All b/c of a little restrictor. Crazy. I guess, contrary to my prior belief that my carbs have been rejetted by a previous owner and require the increased air flow given by the aftermarket drop-in.

Now I have another question. If my plugs indicate I'm running on the lean side (I checked them myself as well as was told by a mechanic that they appeared a little ashy white), what can I do to change that if by installing the restrictor I hindered the performance of my bike. My intent was to richen up the mixture but it richened it too much at the top end. I don't want it to run lean so... do I try and change one of the jets or maybe the air screws at the bottom of the carbs?? The bike is running like a champ at the moment so I don't want to ruin that. At the same time, I've read here and heard elsewhere that running lean hastens wear and tear on the engine. Just throwing that out there. Maybe I'll just leave as is but ideally I could richen it up just slightly. Other than that, I'm completley satisfied with the performance.

a little lean is ok

go up 1 size on the main if you are worried

with fuel $$$$ a little lean might be good!

glad the solution was an easy one!

Quote from: pantablo on May 27, 2008, 11:42:34 AM
glad the solution was an easy one!

Yeah, me too. Thanks again Pablo for your help. 

 

I had the same problem on a stock 2004 gs500f.  As soon as I put in the K&N 5589 Air Filter with restrictor (as per instructions), the bike would reach a flat spot at about 7-8K RPM.  I couldn't go above 80mph on the freeway.  So I took the restrictor out, and the bike runs great.  All stock jets.

Michael