When you cleaned the carb, how were the jets? Specifically, the main jet? The symptoms you have would lead me to think main jet is clogged. BTW, running lean is never a good thing. Might want to just get a stage 1 jet kit while you're at it. Good luck.

 

You might check the three yellow wires under your seat to see if the connector is burnt.

 

Did you check the rubber slide diaphrams carefully for pin holes?

 

yup that was my first thought

 

Are you running the std air cleaner setup?

Have you checked the tank vent line for kinks or blockages?

Are you running stock needles/jets?

Did you check the float level while the carbs were out?

 

Sorry, I should have included this info in the post. I'm running everything stock: exhaust, air filter, needles, jets etc.

I didn't specifically look at the float levels when the carbs were out, though I did make sure that the springs in the needles were still working. If the float levels were off, would I only see this issue at high RPMs?

I looked quickly for kinks in the tank vent and didn't notice anything, but I could absolutely have missed some things. I was thinking of running the bike with the gas cap off to see if the problem is with the vent. I'll follow up as soon as I try it

 

Any ideas at all would be really appreciated.

Symptoms:

[*]Can’t seem to get the same hesitation at high rpms on lower gears,


[/LIST]

This one symptom here says a lot about what the problem could be.

What's different about high RPMs in lower gears and high RPMs in higher gears is the speed of the air flow around/over the bike.

The speed of that air has a direct pressure effect on the open end of the carbs float bowl's vent line. Where that vent line terminates has to be out of the air flow going across the bike. If air flows over the open end of that vent tube the float bowls will pressurize and the bike will starve for fuel. The faster the air flow over the open end the more it pressurizes and the worse the problem.

It is the speed of the air traveling through the throat of the carbs that creates the negative pressure in the chambers above and below the throat of the carbs. The negative pressure is what allows the vacuum pistons to lift and the fuel to be siphoned from the bowls.

Your location is not indicated. Is there any chance that you have a California bike with the emission control valves on it. If yes, then a failure with that system could cause the same symptoms/problems.

Like already mentioned several times, the condition of the rubber diaphrams on the vacuum pistons needs to be checked also.

John

 

I'm currently in PA, but bought the bike and rode it in AZ over the last 5 years or so. As far as I know, the model isn't a CA model, so there shouldn't be any emission control.

Yesterday I had an open bit of highway to try things out and found that it also bogs in 4th at ~65 mph. I haven't pushed it as much in lower gears, but it definitely feels sluggish at high RPM even if it doesn't completely bog down. It really seems like it's either a fuel delivery problem or a vacuum leak.
As I mentioned above, I'm going to pull the carbs again and go through everything with a fine tooth comb and replace anything that looks iffy at all. It is a 97 and I'm sure a lot of the rubber is 20 years old, so it seems like small cracks somewhere might be causing this issue.

 

So, it's definitely not a vent issue. I ran the bike without a gas cap on and still had the same issues.

It also looks like it does this on all gears when the RPMs are high, but only under load (not idling). I guess I didn't notice because it's only been slowly getting worse over time and I must have changed my riding to avoid high RPM on lower gears.

 

have you had the fuel tap off to see if the in tank filter sleeve is clear, does it have another filter added? either could be blocked

Float level low will lean it and can cause issues (Taller than stock measurement when the carb is upside down) is something that is often overlooked

did you remove the main jets and inspect after cleaning to ensure it looked like a clear crisp round hole


and yes check for pin holes in the diaphragm

 

Hi everyone, thanks for all of your help!
Still trying to figure it out, but here's the status. I pulled the carb off again and rechecked the diaphragms. One of them had a small tear in it and the other seemed like it was close to tearing, so I replaced both of the slides, needles and springs. Unfortunately, that didn't fix my problem (though it would have been a problem eventually, so it's good that I caught it now). When I had the carbs off, I rechecked everything with a fine tooth comb. Changed all of the o-rings I could, changed the pilot screw, the float needle and seat, checked float bowl height, used carb cleaner and a set of fine wires to clean all of the jets, etc etc. I'm pretty confident at this point that that carb couldn't be in better shape if I tried!
Long story short, it's not the carb, and I'm thinking it's not fuel either.
I tested the coils (and noticed that one of my spark plug caps has some electric tape on it...). I get 2.5 ohm on both primaries (Clymers says 2.1-2.7) and 31.6 and 32.4 on the secondaries (Clymers says 24-32k). It seems like that's basically within spec, unless 0.4 k ohm is too much? Also, could there be issues that the resistance test wouldn't pick up? Especially if the coils are just having issues under load?

 

Does your bike have a vacuum controlled petcock? Sounds like the problem I was having on my Aero 750 and it turned out to be a tear in the vacuum diaphragm in the petcock.

 

yup could definitely be that, Just replaced my Daughters petcock because of a torn diaphragm (just with a Chinese one while I rebuilt hers, now ready to refit)

 

I don't claim any mechanical skills, but on the vlx there is a vent tube(plugged) that runs down the left side of the radiator that needs draining periodically. Don't know if your's has one or if that could be an issue.

 

I've been having the same problem with my bike. '95 VT1100C2
What I've done to address the problem is just wad up cash and throw it at the bike.
No, but I've replaced a lot, more then the list on here.
Bought for $500 from a buddy who thinks it's cursed.
Here's what's been done as far as fuel/air/fire goes.
Cleaned carbs and replaced all rubber with new (holes in 1 sleeve so went ahead and replaced both)
New ignition cap (front cylinder, tested weak, rear cylinder cap tested fine)
New fuel lines (old ones were crumbling)
New voltage regulator (soldered connections)
New Stator (soldered connections)
New petcock
Replaced vacuum lines
Replaced exhaust and gaskets (2 1/4 mac slashbacks)
Swapped to castrol oil and k&N oil filter (new to bikes, but, I've broke down a few car motors and the shiniest heads always had castrol in them).
New battery (old one was 8 mos old and had a dead cell already)
Cleaned inner air box filter (the metal mesh that was a little deeper in the airbox)
K&N Filter (Last thing I replaced, biggest improvement)
Adjusted carb needles in between each improvement/change.
In between each fix/change I kept riding it. Sometimes it would putter and spit, sometimes it'd outrun mustang or camaro. Out riding for a couple hours last night and didnt' experience any issues. 0-90, High gear/low speed or
Repairs are written in order of how it went down. I'm also sitting on a dynojet kit, but, the bike's running right for now, so, I'm not adjusting much right now. If it stays stable for a few weeks, I'll pop it in.

 

Nope. Didn't fix it. 20 miles into the ride today and it started acting stupid.
got angry and hammered it down. It kept up with the popping and stuttering for about 15 seconds, then it woke up and rode fine for 100 miles. Then it did it again. Popping and stuttering. I tried the hammer down method again with no luck. Got it back to the house. Now, I'm gonna rip it open.

 

Have you checked the state of the plugs for colour while it is in the spluttering mode...might help lock down the cause, as lean and rich can cause splutter

 

I've ran both lean and rich trying to isolate the problem with the same unfortunate results. Unfortunately I don't think it's a problem with fuel or air. Went out again last night and leaned it out some more with the same results. The only difference now is the pop of the exhaust during decel.
i did notice something yesterday, while hammering through the stutter, I noticed my lights heavily flickering. Like there was too much of an amp draw and too little power to supply the plugs.
Not certain what to do about that yet. I'm going to start by checking all the contacts and make sure there is not an odd short somewhere.

 

I mean you've done a lot to this, it must be electrical. Somewhere there is a lousy connection.

 

Rear cylinder plug. Front cylinder had a lot of blow by crusted on it, but, I expected that running the mix as fat as I did. I've cleaned it off and reinstalled. Hopefully I'll be able to ride today and get a pic this evening. Right now, I'm about to yank the tank off and check my plug wires and the signal wires feeding the ignition caps.

 

Not riding tonight. Took it out earlier to grab some eggs and it spit on me. Now. Where's my ohmmeter?

 

Well, while I had the carbs out to be able to access the plug wires, I decided to rejet it for funsies.
Turns out, it already had 175 jets in it. Factory pro I believe (jets had factory 175 on them and that's as close a guess as google could get me).
So, naturally, I replaced them with the dynojet kit.
Unfortunately, it's probably not going to have much effect on the stuttering issue.
So, back to the fire. I'm cutting an inch off of each set of plug wires to get back to good wire. Will update as soon as I'm rolling again.

 

Last congruent post for me. Sorry for the thread jack.
BUT, might have it fixed. Looks like a bad connection on the ignition coil. Other then playing with the already jetted carbs, that's all I did. Cleaned the signal wires, pinched the connectors on them a little bit and cut an inch off of each plug wire.
Took it out for a hour spin around the block tonight with no issues.
So, my advice to the original poster is to check his wires.