Ahhhh, the smell of half burnt fuel in the evening air...

[natemoen]

First off you need to take care of the leaking carbs. Don't know if you have the octy anymore but if you do you should not get any gas into the carb with the bike off and the petcock on Prime or On, only on Reserve shoul you get gas. Without the octy you would always get gas on any of the positions except off. If anything else happened you need to fix your octy.

Now you need to look at your carbs. The float valves (little pin that goes onto a brass seat above the floats) should stop the fuel from coming out of the carbs and into the airbox (and/or into the crankcase and then trashing bearings) so something is holding the lost valves open. Often times they get hung up on the bowl gasket and a gentle hit from a screwdriver handle on the bowls fixes it. If that doesn't then the float valve is leaking and needs to be replaced.

For the syncing, be very descriptive for us about your tool, pics would be great.

Then be very descriptive about your process of syncing.

[motoman]

*brain explodes*

Good to know others have survived this nightmare.

Ok- Yes, Carb 4 fills immediately with fuel and dumps out all over everything, which is awesome. (that's thick sarcasm) not just on PRIME but ON/RES as well. Feel free to speak to me like an infant- what does that mean??

I pulled the bottom of the airbox off to get a better look at whats going on- it is definitly #4 that is spewing gas out of the airbox. When you say Float valve do you mean the valve seat assembly?

The excessive reving continues, I tightened up the manifolds, I'm not sure what else could be allowing excess air in that causes the over-reving. The reving is happening without being hooked up to the vacuum synchronizer... so it's something 'bike' related.

I'll pull the carbs off and bench synch as everyone has suggested, but any suggestions on what else I need to do while they are aoof the bike? A reminder- all have been cleaned thoroughly, but outside of that I'll try anything.

Thanks!!

Gonna have to pull the carb bank and resolve the #4carb overflowing fuel. That's also PART of the overrevving issue. (Pull ALL the bowls and leaving gasket in place, x-acto knife or similar following inside of carb bidy, trim excess kasket off so your positive it isn't interferring with float). They may LOOK okay, till the bowl is pulled on tight causinng gasket to squish a bit pushing gasket edges inward.

[fredintoon]

Ok- Yes, Carb 4 fills immediately with fuel and dumps out all over everything, which is awesome. (that's thick sarcasm) not just on PRIME but ON/RES as well. Feel free to speak to me like an infant- what does that mean??

It means the engine is running or the gas tap vacuum is hooped. Otherwise the vacuum operated gas taps (Standard) or Octopus (Special) would shut off the gas on ON/RES.

I pulled the bottom of the airbox off to get a better look at whats going on- it is definitly #4 that is spewing gas out of the airbox. When you say Float valve do you mean the valve seat assembly?

#4 float ain't working. Possible causes:- float has lost buoyancy; float needle valve is hooped or jammed with crud; float bowl gasket blocking float movement; float level all wrong. Q. Did #4 carb flood before you had it apart?

The excessive reving continues, I tightened up the manifolds, I'm not sure what else could be allowing excess air in that causes the over-revving. The revving is happening without being hooked up to the vacuum synchronizer... so it's something 'bike' related.

Lotsa air going in those vacuum spigots unless you re-capped them.

I'll pull the carbs off and bench synch as everyone has suggested, but any suggestions on what else I need to do while they are off the bike? A reminder- all have been cleaned thoroughly, but outside of that I'll try anything.

Bite the bullet. Clean them yet again
Thanks!!

[jetmechmarty]

I'll pull the carbs off and bench synch as everyone has suggested, but any suggestions on what else I need to do while they are aoof the bike? A reminder- all have been cleaned thoroughly, but outside of that I'll try anything.

Something is wrong with the #4 float valve. The float could be hanging up or there's trash under the needle. You need to fix that for sure. Do you have new bowl gaskets? #4 could be rubbing on the float.

Do you still have the vacuum shutoff valve (octopus/octy/spider valve)? It's mounted on top of your carburetors on the left side. It has a vacuum line and four fuel lines going to it. If your's is there, it's leaking. With the engine off, fuel should flow only in the PRIME position. You need to rebuild that valve. You can bypass it, but before you do, consider this. You're riding the bike and have an accident. You go down and the bike is on top of you. The tilt switch has shut of the ignition and the vacuum shutoff has stopped the fuel flow. But wait! You got rid of that valve. Fuel is pouring out of the carburetors and onto the pavement and soaking your clothes. Will there be a fire? I just thought I throw that out there before someone tells you to just throw it away. At least now, you know why it's there.

[BA80]

Just throwing it out there but I had an issue with that on one of my bikes and it drove me nuts for a while. All the valves were good, float levels good, no binding..................after taking the carbs off several times I just happened to notice that the one float sloshed when I shook it.

A pinhole in the float and it was filling with gas.

[DGXSER]

its all interconnected, leaking float is causing one cylinder to feed fuel with no throttle, causing engine to rev, pulling the others along.

Ok, so now we need to see what year the carbs on your bike are from. Look HERE. This is important because the newer style have plastic floats which should all but eliminate issues with bad floats. You do have an issue with no 4 float valve, the metal piece hanging off the float into that brass seat. The gasket is a source of the float hanging up, or the valve and seat could be worn out, need replacing. If I am not sure how old they are, I always replace the float valve and seat when I clean the carbs. In addition to all the other listed ways it can leak, sometimes the floats just get hung up by hanging at an angle. Often I find if you tap on the float bowl while it is filling a stuck float will free itself and work fine from then on.

As to petcock operation, on the special models, we have a vacuum operated valve mounted above carb no 2. It only opens when vacuum is applied by the engine running. If it is working properly, with the petcock in ON or RESERVE, fuel only flows to the carbs with the engine running. However, it is not at all uncommon that they do not work, need to be rebuilt. With the petcock in PRIME, fuel flows all the time, bike running or not. So, do you get fuel leaking out no 4 with the engine running, or only when the engine is not running, or only when the engine IS running?

either way, the float valve needs to get fixed, then you can move on to other issues.

[BA80]

A leaking float WON'T cause an engine to rev. It may kill a cyilinder by flooding it but without air fuel won't burn.

[Zeston]

The bike is a 79 Special, metal floats. On dissamble I damaged one very slighlty however; it was not the the #4 float. (The damaged one is repaired and seems to be performing fine) I am using the original float bowl gaskets and they also doing their job ok.

I pulled the carbs off again last night:
-I re-adjusted the float levels to be sure but all were still very close to 25.7mm per spec.
-#4 did have a hanging float valve. It seems free after I cleaned it again- but obviously the is an issue that needs replacing (ordering one this morning)
-I bench synched the carbs before I put them back on, but at this time synchronizing on the bike is an afterthought.
-The octy is definitly "hooped"
I recently bought a petcock kit from BikeBandit thinking that was the issue, it came with a new diaphragm gasket for the vacuum, is there anything else I need to rebuild it? I will buy a new one if anyone knows where to go for one- I will NOT buy a used one..

You folks are awesome, I greatly appreciate everyone's time and effort in responding. Seems like I've got 2 issues combining to generate the results I'm getting.

[GLoweVA]

A leaking float WON'T cause an engine to rev. It may kill a cyilinder by flooding it but without air fuel won't burn.

I think I might have to agree with you Greg, But let's not put the cart before the horse.
Let's fix the overflowing #4 first, then If the bike is still reving, then let's look for vacuum leaks and such.

[BA80]

The diaphragm is all you need to rebuild the octy. Just be sure all the sealing surfaces are clean and flat, not warped from someone over tightening the screws trying to stop a leak.

I ran the octys on my specials for a long time too but just this summer I took them off. I got tired of fixing them all the time. One less thing to worry about.

What kind of damage did you do to that #4 float? If you think it's that float swap it to another carb and see if the leak follows.

[Zeston]

What kind of damage did you do to that #4 float? If you think it's that float swap it to another carb and see if the leak follows.

It wasn't #4 float that was damaged, #4 float is good.

[BA80]

I think I might have to agree with you Greg, But let's not put the cart before the horse.
Let's fix the overflowing #4 first, then If the bike is still reving, then let's look for vacuum leaks and such.

I agree George however, I'll have to throw out an objection to a vacuum leak causing a revving issue on a carbureted engine also. It may cause a problem on a fuel injected engine but on a carbureted engine it'll just make it run bad. Air doesn't burn real well by itself. If you want to see what I'm talking about pull one of the vacuum caps off of a boot while the engine is running and see what happens..

The revving issue is going to be the sync or hanging throttle linkage.

[GLoweVA]

Greg, True it could be just as simple as the sync.
Now that Ed's got the overflowing carb thing figured out, then he can try syncing again.

Ed,
I'm taking a little trip up to Richmond Sat morning to get my wife's birth certificate, I MAY be able to talk her into a little detour and we can swing by and I'll help you try to sync your bike.
Shoot me a PM if you think you want me to swing by Sat.

[BA80]

It wasn't #4 float that was damaged, #4 float is good.

I read your post wrong, I skimmed it and missed that the float that was damaged wasn't #4.

If a float valve is hanging it's usually due to the float dropping too far and allowing the needle to get cocked in the seat. There is a tab on the back of the float where you can adjust the float drop.

One other thing to look at is the little composite gaskets that go between the seat and the carb body where it screws in. If they get over tightened they can split and cause an issue. BTDT.

[DGXSER]

Get the new float valve in, and install that before you even put the carbs back on the bike. See how things go from there.