Help me with Surging issues please

[thedaydreamer]

Hi all
2000 Vs14000, came to me a bit dirty and with no mufflers

I did full maitnence on this bike, both carbs fully disasembled meticulusly cleaned, all OEM components except for new bowl gaskets and float needles and I added one extra shim underneath the OEM one, carbs synced both high and low speed

I added cobra slash cut slipons, jets are all OEM and mixture screws are 2.5 out in front and 1.75 rear
Bike is fast for sure, but I am expericecing slight surging at low speeds, top end and throttle response is great with no flat spots or issues
AND is seems like the idle is off, not clean and erratic and the left muffler does not sound like the right, its weaker and piffy at times
Comprression is 165 on both cylinders, new plugs, and oil

I cannot dectect any vaccum leaks and it feels like some sort of idle circuit issue and when I was doing the low speed sync and bringing the sync guages close, it seems like the closer I got the more erratic the idle got, I have no reason to belive the guages are off, but should I tune to the guages or my ear?

Any ideas from here or am I missing something?

TY all

[sky02]

Have you checked the air filters? Sometimes they are torn from being old and dry. And particles clog the jets.
Mixture screws looks quite good it should be around that. Idle should get smoother with good low speed sync and mixture. Maybe your gauges are off. Or the choke cables are stuck.

[thedaydreamer]

HI
Yes fully cleaned air filter boxes, new oiled filters, have no reason to think choke is stuck, it kind of baffling me becasue I went over this bike so intently
MAYBE I should tune idel sync by ear and not the guages?

[Designer]

When you say,..."Tune The Idle"....are you speaking of the Carb Balance, or Mixture setting?

Why I ask is that the only way to get Maximum Best Adjustment regarding Carb Balance is with a Vacuum Gauge. As to Idle mixture I go by Ignition sound and testing the Exhaust Gases at the end of the Pipes to see if I have a good burn.

[thedaydreamer]

TY
BTW - Are you the designer that makes the springs for this bike?

I guess I am referring to the sound of the idle by ear, wheather it be by mix screws or vac guages
I just went out there today, removed the 2nd shim from the carb needle and hooked the sync guage back up
syc looks great and im not sure of the turns of of the screws, I went by sound this time

it idles nice, but dips a bit upon rev, which tells me rich, but I am getting what I think is lean popping upon decel

Its still fast, but something feels off a bit , there is surging at low speeds , am open to ideas

[sky02]

Can you record how she idles? Maybe the idle speed is off. Have you set it using the tachometer? In first post you are saying that the left muffler is weaker thats rear carb and cylinder. Do you have a good seal beetwen the airbox and the rubber connector to the carb. If you dont heat it or live in a hot climate it is hard to put in tightly on.
Fuel level in carb bowls is correct?

By low speed surging you say that you dont get a steady cruise at certain speed and gear or don’t accelerate satisfactory at that speed and gear?

[hillsy v2]

Its still fast, but something feels off a bit , there is surging at low speeds , am open to ideas

The front carb lays flat on these bikes and the needle jet can get ovaled out over time - it's #8 in this pic:



If that happens you can get erratic fueling and surging at cruising RPM. Worth checking but if the carbs are out of sync and the idle mixture screws aren't set properly it can do the same.

[thedaydreamer]

Is #8 the needle jet fixed in the carb or can it be replaced?

I was actually thinking today, maybe just get a new set of diaphrams on amazon and get a dynojet stage one kit, with just the needles and drill it out,,that way I can play with it and leave the OEM intact and see if I get any gains,,,I get it that OEM is best, but Ive had good succes with aftermarket stuff and its worth the gamble to play with

[sgtcall]

TY
BTW - Are you the designer that makes the springs for this bike?

Designer is the one that makes the springs.

[sgtcall]

When you say,..."Tune The Idle"....are you speaking of the Carb Balance, or Mixture setting?

Why I ask is that the only way to get Maximum Best Adjustment regarding Carb Balance is with a Vacuum Gauge. As to Idle mixture I go by Ignition sound and testing the Exhaust Gases at the end of the Pipes to see if I have a good burn.

Designer, just wanted to get you back in the thread. There is a spring question for you.

[hillsy v2]

Is #8 the needle jet fixed in the carb or can it be replaced?

Remove the screw #10 and the needle jet will come out. You can visually inspect if there is any ovalling without removing it - take out the slide with the needle and you will see the jet orifice.

If it looks anything like this it needs replacing....

[thedaydreamer]

Good info, I had no idea, should I inspect the rear as well or only the downdraft carb suffers from this?

How did you find out about this being an issue?

Can someone have designer chime in, I have some questions and interest about his springs

[sgtcall]

Good info, I had no idea, should I inspect the rear as well or only the downdraft carb suffers from this?

How did you find out about this being an issue?

Can someone have designer chime in, I have some questions and interest about his springs

I sent him an email.

[hillsy v2]

Good info, I had no idea, should I inspect the rear as well or only the downdraft carb suffers from this?

How did you find out about this being an issue?

It mainly affects carbs that are laying flat (or close to) as gravity pulls the slide needle onto the side of the needle jet and it wears over time. But if you have both carbs out for sure it's worth checking both. And in the grand scheme of things needle jets are not that expensive to replace so it might be a good thing to do as a preventative measure.

How did I find out about it? That pic I posted of the ovaled jet was from the Factory Pro site. I had a 2000 model ZX9r that had lay down carbs and it had the same issue. Unfortunately they were pressed in jets so not an easy fix. Also the 1500 Intruders had both carbs laying down flat....with pressed in jets...there's a company called GMAN Industries that had a thriving business replacing the jets in these carbs (Gary still does that work). I sent my 1500 carbs to Gary about 10 years ago for new needle jets and the difference was night and day.

Good luck with it - carbs can be finicky (especially if they are old) but getting them right is rewarding

[Designer]

BTW - Are you the designer that makes the springs for this bike?

Yes,.. that is me.

it idles nice, but dips a bit upon rev, which tells me rich, but I am getting what I think is lean popping upon decel Its still fast, but something feels off a bit , there is surging at low speeds , am open to ideas

This sounds like it could be a problem that possibly has two different sources.
When you say it... "surges"...is that at steady-state RPM,..(light load) .or when you are accelerating (heavier load) ?

Also, when you mention popping on decel,..is that an immediate response, repeated ...or something that happens somewhat intermittently?

[thedaydreamer]

Hi

The surging is just at steady state say 30 - 40 mph, holding the throttle at say 2500rpm and just going slow through the neighborhood, there is surging that you can feel,,,,,

When you hit the throttle it takes off, nothing of the sort on acceleration, its crisp and fast and does not seem to do it at say 55mph

The popping is more like when you let off it will give you one good "snap" or "pop" , there is no consistant popping or bubbling upon decel

Are you still selling your springs can I still get a hold of a set?
TY

[Designer]

Hi The surging is just at steady state say 30 - 40 mph, holding the throttle at say 2500rpm and just going slow through the neighborhood, there is surging that you can feel,,,,, When you hit the throttle it takes off, nothing of the sort on acceleration, its crisp and fast and does not seem to do it at say 55mph

Since the Main Jet is the dominate one supplying fuel at 55 MPH, that would seem to indicate that it is performing as it should. So before you go through all that major work of tearing back into the Carbs to check the Main Jet,.,...let's check something out first.

......The popping is more like when you let off it will give you one good "snap" or "pop" , there is no consistant popping or bubbling upon decel

This could be the Coasting Valve. They are pretty much easily accessible on the outside of the carb. Can you tell which Cylinder is Popping? You might want to take it apart and see if it is sticking or dirty first. Then put it back in and go for a Ride.

.....Are you still selling your springs can I still get a hold of a set?

Yes,. let's talk about this via E-mail. My Address is available here:
memberlist.php?mode=viewprofile&u=56

[thedaydreamer]

sent you email, let me know if you got it

[thedaydreamer]

Also, I dont know where the coasting valve is I cant find it on any diagrams, any ideas?

[sky02]

On the side side of the carb. No 34 on the diagram that was posted before. Its under round cover with 3 small bolts.

30-40 mph and 2500 rpm so you are on 2 or 3 gear because if you are on 5th thats rather 1500rpm and thats almost idle. Vs1400 make most torque slightly above 3000rpm. The engine wont feel comfortable at that rpm under load.

Mine also gives sometimes one small pop from the left muffler with hard deaccel.
You can check the air passages as there are 2 air jets (one should be cut off by that coasting valve during deaccel) maybe there is something there or the coasting valve is stuck.