slow/ fast jets???

[Ferris Leets]

     I did not want to hijack the thread on the general board and this seems like the right place to ask.
     Every time someone comes up with a plugged slow jet problem the advice is to run the solvent (insert brand) through at low RPMs usually suggested as under 2000.  My understanding of how these carbs work, leads me to believe that the high speed jets function at over ~1/3 throttle.  But, now here is where I am curious and would like information.  Again my limited understanding leads me to believe that the low speed jets are still passing as much gas (!) as they did  before you reached 1/3 throttle.
    The question is- why the need to run the engine slow to get the cleaner through the slow jets?

[Hoser]

Thhe lower the rpm, the more of the mixture goes through the slow jets, when the stumble goes away that means the high speed jets have taken over.  Some say if the choke is applied at the low speed it helps.  I  prescribe to that theory.  Hoser

[Ricky-D]

I think you are correct since all three systems are overlapping and continue to work as they are called upon by the throttle setting.

The low speed system relies upon ports that are located in the bottom part of throat area, I think three prior to the butterfly and an additional port after the butterfly. This is the controllable one by means of the adjustment screw.

The needle is a variable jet that finally, at wot, is only controlled by the main jet orifice.

All are always in the fuel stream.

***

[98valk]

search is your friend  just posted this last wk.

http://www.valkyrieforum.com/bbs/index.php/topic,30804.0.html

[Ferris Leets]

search is your friend  just posted this last wk.

http://www.valkyrieforum.com/bbs/index.php/topic,30804.0.html

Went there. Still does not answer my question.  Isn't the fuel still flowing through the slow jets?  So why keep the rpms low?

[X Ring]

So the fuel/cleaner mixture is only going through the slow jets.

Marty

[98valk]

search is your friend  just posted this last wk.

http://www.valkyrieforum.com/bbs/index.php/topic,30804.0.html

Went there. Still does not answer my question.  Isn't the fuel still flowing through the slow jets?  So why keep the rpms low?

1/8 throttle should be your hwy cruise speed, going more starts to use the needle circuit more. changing PJ size will move this range up or down.
The PJ contributes all through the throttle as do all of the circuits. they all overlap. FactoryPro has other articles on the subject, plus a google search will bring up more.

[Ferris Leets]

Why would less fuel flow through the same jet?  Is this one of those things that is assumed to be correct but has no basis in data?

[Warlock]

Why would less fuel flow through the same jet?  Is this one of those things that is assumed to be correct but has no basis in data?

While running lower rpm's the demand is greater thru the slow jets. Let me use a water valve for explaning. Lets say you have 1 valve open with 10 lbs of pressure. Once you start to open another valve the flow will get less because the flow is needed at the other valve. Now you are sharing the same pressures but two different places. With less pressure att the first valve. I how this makes since.
David

[JimC]

Also,

when you are running at high rpm, you are going to go through the gas in your tank much quicker, with most of it going through the high speed jets.

Running the lower rpm range will put more of the tank of gas through the low speed jets, therefore you are putting your additive to better use, on the jets that need it.

When people say to run at low rpm,  they don't mean that you can not go fast, they are just trying to describe the best way to get the conditioner, cleaner, to the jets that need it most.

Jim

[98valk]

here is a great long write-up

http://www.drpiston.com/Cvcarbs.html

[codetonic]

One conclusion I could come to is that once warm, an idling engine will get most if not all it's fuel through the Pilot circuit. As well, the fuel in the Pilot circuit would be traveling slower (spending more time in the passages and jets). Therefore, when using Seafoam or your favorite cleaner, idling would be the ideal cleaning speed. How long can a Valkyrie idle without overheating?

[X Ring]

Not something I would recommend.  Ride it at slow speeds.  Cooling just doesn't involve the cooling system.  It also requires air moving over the heads and exhaust system and through the radiator.

Marty

[Ferris Leets]

here is a great long write-up

http://www.drpiston.com/Cvcarbs.html

Very good article.  That is the clearest and most in depth desciption of carbs that I have ever read.  Answered another question I had about how the enrichener system ACTUALLY works.
    I see the logic of the less fuel being used by the needle so more goes through the slow jet, but at cruising speeds the the throttle is nearly closed so the needle is not very high anyway.
David,
     Your fluid logic is correct if the pressure/volume is constant.  However in this situation the air voulume is increasing as the throttle opens, the vacuum drops until the slide is sucked up and then the vacuum pressure increase to the original pressure.  So the pressure on the gas at the slow jet is the same as it was so it should feed the same amount of fuel.
    My conclusions---The best method has been described.  Add the sovent, fill gas, run it at least long enough to  get the solvent to the jets, let it set (overnight), then ride at a normal speed, let it sit, ride till near empty, refill and be happy.
   I am not going to flog this deceased equine any more.  Now I will move to a new time wasting thread on the high speed jets. 

[Warlock]

here is a great long write-up

http://www.drpiston.com/Cvcarbs.html

Very good article.  That is the clearest and most in depth desciption of carbs that I have ever read.  Answered another question I had about how the enrichener system ACTUALLY works.
    I see the logic of the less fuel being used by the needle so more goes through the slow jet, but at cruising speeds the the throttle is nearly closed so the needle is not very high anyway.
David,
     Your fluid logic is correct if the pressure/volume is constant.  However in this situation the air voulume is increasing as the throttle opens, the vacuum drops until the slide is sucked up and then the vacuum pressure increase to the original pressure.  So the pressure on the gas at the slow jet is the same as it was so it should feed the same amount of fuel.
    My conclusions---The best method has been described.  Add the sovent, fill gas, run it at least long enough to  get the solvent to the jets, let it set (overnight), then ride at a normal speed, let it sit, ride till near empty, refill and be happy.
   I am not going to flog this deceased equine any more.  Now I will move to a new time wasting thread on the high speed jets. 

I was using my discripition on a set speed not running thru different speeds. Anyway glad things are alright.
David

[Ferris Leets]

All of this typing and I haven't even got a carburetor problem.  I just get curious about things.