How to throttle two carbs with dual air intake?

Hey LD,

Bummer. Sounds like one of a couple of things... You did not specify what BRAND your bike is, but with the slide comment, I presume a Mikuni or similar type of carb.

So the artificial enrichment circuit is actuated during choke operation. This circuit only works with the throttle plates in the IDLE position. ANY throttle and that circuit drops out of the picture and the idle/slow/main jet circuits take control.

You COULD have a huge vacuum leak, and that would cause what you describe. Look carefully, squirt bottle some water around the intake/carb/manifold areas. Any change in idle is suspect. But you may not be able to achieve this, based on choke only operation.

SO, my thought is something is plugged in your carb. This happens with old gas and stagnation. Often the enrichment circuit will flow, but not the idle circuit. The only remedy is surgery. Typically you pull the carb(s) so you can inspect well on a bench. Pull the float bowl and look for foreign material of any kind. I have seen moss like growths in there... Perform an overhaul, with the long submersion, followed by flushing and high pressure air..

There is one other, fairly Bonsai method that works: You fire up the bike, with the air cleaner off.... Get as much engine speed as you can... One hand on the throttle, ready to open, and briefly cover the entire carb intake with the palm of your hand, at the same time, you need lots of throttle. What this does is sometimes dislodges a blockage. Really works well on lawnmowers. This takes a time or two for you to get everything synced, but you need lots of throttle and full intake air restriction. Sometimes works, sometimes not. I always worried about being successful as that means there is some chunk of something floating around somewhere in my carb. I would perform surgery.

I hope this helps.

Doc

if you can not acheive idle speed without the engine dying-you could try to spray flamable type carb cleaner or brake cleaner while someone is helping you maintain a minimum idle speed befor it dies out-this may help you locate an induction leak such as an air intake gasket leaking and fooling the mass air flow sensor values

Is engine condition good???? comperssion should be in the range of 150 psi. have you checked tha air box, filter, inlet track for proper condition and no blockage(dirt dobber nest???). Check for air leaks at the intake manifold by spraying arouind the area with carb cleaner while idling, any change in rpm indicates a leak. Re check your work in the carb. A "cleaned carb " and a properil overhauled and adjusted carb can be 2 different things.

chances are it is most likely the throttle position sensor, next to the air intake, it would not hurt to clean the air intake with carb cleaner, be sure to open the throttle so that the carb spray can penetrate deep into the air intake & clean both sides of the butterfly.

P0506 Idle Air Control System RPM Lower Than Expected, check the idle control sensor,, also, clean out the throttle body opening and flap , follow the air intake tube to the carb or throttle body , spray some carb cleaner in there and clean off all the black ,, wipe with a clean cloth and try again

To change the choke cable, you must take the carb off the engine. Remove the air filter and backing plate. Take the nut off the backside of the choke cable and let the cable come out of the bracket that holds it. Make sure the petcock is turned off and disconnect the fuel hose at the carb. Loosen the throttle and idle cable at the handlebar throttle assembly. Pull the carb out of the intake manifold seal. Work the throttle and idle cables out of their positions in the carb. Bring the carb with the choke cable out and away from the engine. Take the choke cable out of the carb with a 14mm open end wrench. Take the plunger and spring off the old cable and swap it to the new cable and reinstall the choke cable. Put the throttle and idle cables back onto the carb, put a new intake manifold seal on the intake manifold and push the carburetor back into the new seal. Put the choke cable in it's bracket and secure the nut. Be careful and do not over tighten the nut as the plastic cable housing will break. Reconnect the fuel line, the vacuum line, and anything else that was taken off. Replace the air filter backing plate and the air cleaner. Readjust the throttle and idle cables making sure that the throttle operates freely and returns when let go on it's own. Never put any kind of lubricant on the choke cable. There is a knurled wheel that you can use to tighten the cable so that it stays where you put it.

Ride Safe
Steve

To replace the enricher cable on the stock Kiehen CV carb, you must remove the carb from the engine.

Remove the air cleaner cover, air filter, and backing plate. To get the backing plate off, you must remove the two large union bolts that go to the heads on either side of the ari filter backing plate and the three smaller bolts at the mouth of the carb. Loosen the adjustment of the throttle cables at the handlebar throttle grip. Take the nut off the backside of the enricher cable and it fall loose from it's bracket. Disconnect the fuel line from the carb, make sure the petcocik is turned off. Now, twist the carb slightly and pull until it comes out. Make sure you guide the enricher cable out. Once you get the carb out far enough, remvove the throttle and the idle cable from the carb and bring the carb on away from the engine. Now, use a 14 mm wrench to unscrew the enrcher cable from the carb. You'll have to change the elbow, nut, spring, and needle from the old cable to the new cable and reinstall it on the carb.

To replace the carb, guide the enricher cable back between the cylinders. Reconnect the throttle and idle cables on the carb. Replace the intake manifold seal (round rubber boot on the intake manifold) and lubricate it with a bit of silicone spray or something. Push the carb as far as you can into the seal. Reconnect the fuel line and adjust the throttle cables. Make sure you don't get them too tight and that the throttle works like it should. Replace the air filter backing plate, air filter, and air filter cover. Put the enricher cable up into it's bracket and tighten the nut on the backside. Be very careful tightening the nut as the plastic housing breaks easily. Tighten the nut just tight enough to securely hold the cable. Check the operation of the carb and make sure it operates smoothly and correctly. Now, you should be ready to ride.

Good Luck
steve

In order to replace the choke cable, you must take the carburetor off. Start by taking the air filter assembly off the engine, including the backing plate. Then, disconnect the fuel line, drop the choke cable from it's bracket on the left side of the bike, and loosen and disconnect the throttle cables. There is a vacuum line that plugs onto either the back of the carburetor or the intake manifold. Once all this is loose, pull the carb out of the intake seal and guide the choke cable out of with the carb.

Now, that you have the carb out, using a 14mm wrench, unscrew the choke cable where it goes into the carb. You'll have to take the plunger and spring off the old cable and put it on the new cable. The screw it back into the carb.

Reconnect the throttle cables and vacuum lines and install the carb back into the intake using a new intake manifold seal. If you don't replace this seal, you may wind up with a vacuum leak and have running problems. Reinstall the fuel line and air cleaner assembly. Adjust the throttle cables and make sure the carb works correctly. Never lubricate the choke cable. If you do, it will not stay out when you pull it out. There is knurled tension wheel behind the knob when you pull the knob out. Tighten or loosen the tension on the cable with this. Do not over-tighten the big nut on the backside or the cable housing will break,, cheap plastic stuff.

Good Luck
Steve

To replace the "choke" on the carb of your 2000 Softail, you much take the carb off the engine. Take the air filter cover, air filter, and air filter backing plate off the engine. Loosen and disconnect the throttle cables and fuel hose. Loosen the nut on the backside of the "choke" knob and take it out of it's slot in the bracket. Twist and pull the carb out of the intake manifold bringing the "choke cable" with it. Once out, use a 14 mm open end wrench to unscrew the cable and plunger assembly. You'll have to swap the spring and plunger from your old cable to the new cable and reinstall in reverse order. Always install a new carb seal where the carb pushes back into the intake. Make sure the throttle works smoothly and snaps shut when you relaease the throttle grip. Never lubricate the "choke" cable. Be careful when tightening the nut on the backside of the cable knob end. The assembly is made of plastic and breaks easily. To adjust the tension on the cable. turn the knurled ring just behind the choke knob.

Good luck
Steve

First, remove the complete air filter assembly, Then, remove the fuel tanks. Remove the carburetor. With all this off, you can remove the intake manifold and replace the gaskets.

To remove the tanks, first remove the seat and the dash cover. With this off, you can get to the bolts that hold the tanks on. There are two bolts at the front and one at the rear of each tank. The tanks are connected by a fuel line at the bottom and a vent line at the top. You'll have to drain the fuel from the tanks but you won't be able to get it all out. When you take the "fuel crossover line" loose at the bottom of the tanks, gasoline will go everywhere.

To get the carb off, loosen the two cables and disconnect them from the carb. Disconnect the vacuum line for the VOES and the petcock from the back of the carb. Loosen the nut that holds the enricher cable to the bracket on the left side of the bike. The enricher cable stays with the carb. Pull the carb out of the intake manifold.

Now, remove the two bolts from each head that holds the intake on and it will come off.

To reinstall the intake simply reverse the procedure. However there are a few things to watch for. The intake flanges that bolt to the heads are marked "F" front and "R" rear. Do not mix them up. The beveled side goes towards the head and the gasket goes on the intake to match the bevel.

When you put the intake back on, leave it loose because it must be lined up. With the intake loosely bolted to the heads, stick the carb back into the intake manifold and bolt the air filter backing plate back up using the three screws for the carb and the two large bolts that screw into the heads. This aligns the intake manifold with the rest of the induction system. Failure to properly align all the induction components could result in a vacuum leak even with the new gaskets. If you have to push the carb in any direction to get it to bolt up with the air filter, something is wrong. Once you get everything aligned, tighten the four bolts that hold the intake to the heads.

Before starting the engine, make certain that the throttle cables are operating the carb correctly. You don't want to start the engine with the throttle wide open. Lift the slide and verify that the throttle plate is closed in the carb. When you open the throttle wide open and let go of the throttle grip, the carb should "snap" shut. If it doesn't, you've got something wrong. Make sure the throttle works properly. Failure to do so can cause serious injury or death.

Good Luck
Steve