Topic: Choke not working ? *UPDATE* Filthy carb

[MOONDOGNYC]

So last week, I tune the carbs and the bike ran great. 
Got the body work back from the painter and fill the tank with gas.
Pull the choke....and  it doesn't' work. It was warm enough to start the bike without the choke, so I just revved it to about 2000 or so. It ran rough and no matter how warm it got, the choke was unresponsive.
  The bike won't idle well and runs like hell...  I am totally bummed out.
How can the choke stop working  ?  The cable is attached and moves the assembly when actuated. 
  Help ?

[iron_worker]

How do you know the choke isn't working? Have you pulled the airbox off and watched the slides move?

IW

[MOONDOGNYC]

No. I have not. I just watch the cable pull the linkage and it moves like it used to.

[motosan]

Was the bike idling fine before the tuning?

[MOONDOGNYC]

Before, no.  After I was done, perfect.  Waited a week to put the shiny bits on and now, I pull hte choke lever and get no response. It also runs like cr@p.

[motosan]

just covering the basics....checked all connections for carbs, sparks, and etc?  I once forgot to put the carbs all the way into the rubber boots....  Also I managed to forgot that I closed the idle screw all the way, thinking i had them turned out the right amount.

[MOONDOGNYC]

After synching the carbs, it was rolled into the garage.
I just checked and the butterflies and the control rod are functioning. Shoudln't the idle go up when the choke is pulled?  Maybe I am missing something.

[motosan]

Shoudln't the idle go up when the choke is pulled?  Maybe I am missing something.

Not always.  I'm not an expert in how fuel/air ratio and choke affect rpm, so someone else can explain my experience of choke having the complete opposite effect on rpm.   Actually pulling choke (closing the butterfly) brought down the rpm while pushing it (opening) made it surge on mine.  There was a tiny vacuum leak on one boot, and my carbs had slow jets 2 size too big for stock everything.  And changing the boot and slow jets made it perfect.  (i know it probably won't apply to your situation....)

you might have overlooked something very basic. 

[78whiteorbs]

hellacious induction leak. what year and model bike is this>? obstructed gas flow? think what has changed since it last ran. You said you got the tank painted, possible blockage somewere in the fuel/air flow in the tank>?  pull the air box off and see if the choke is choking. Is something  screwy with mounting of the cables  Just throwing out ideas.

[MOONDOGNYC]

OK... I had sometime to look at the bike yesterday.  Enough was enough and I pulled the carbs. 
Not happy to see what I've found. While I originally had clean carbs, they were now filled with a gray sediment in the float bowls. The overflow on the #2?carb(with accelerator pump) was clogged ! The throttle plates opened perfectly but the issue was a dirty set of carbs.
   I have them apart now and will begin the clean up phase.
 I think that when I got the tank back from the painter, there was media left in the tank from the prep work they did. It's my only guess. I will be installing an inline filter after cleaning the carbs and cleaning out the tank. Here are some pics...
 Look at the sediment on my finger in the last pic. As well as the sediment in the manifold boots on the bike.   *sorry for the iphone pics.*

[harisuluv]

Cleaning the carbs is good, yes.

However, I would check your gas tank vent, often times after painting it will clog the vent and gas will not flow properly to the carbs via gravity.

[MOONDOGNYC]

Thanks Haris...let me ask...
Isn't the vent in the gas cap ?  The only other vent I see is the one the goes through the tank via the hole under the gas tank locking door. It looks like a drain for overflow only.

[Bootlegger56]

Don't forget to replace or clean out the fuel lines when you rebuild the carbs unless you like pulling the bowls to clean the jets and needle seats.  I cleaned my bowls three times before I figured out that I had crap coming out of the old fuel lines.  The bike had been sitting for years.

[toytuff]

Thanks Haris...let me ask...
Isn't the vent in the gas cap ?  The only other vent I see is the one the goes through the tank via the hole under the gas tank locking door. It looks like a drain for overflow only.

Yes, in the cap. Other is for overflow.

tt

[lucky]

I wish you would tell us what year the bike is and if it is a CB750  or what.
A motorcycle does not have a body. It has a gas tank, fenders, side covers, and maybe a fairing. No body. IT is not a car.

You say you tuned the carbs. Then you say the choke is unresponsive in warm weather.
The choke is for cold weather, or just for starting when the engine is cold.
How can you say you tuned the carbs but yet you have no idea if the choke is connected?

The manual choke is not just an ON or OFF deal. Sometimes the engine only needs partial choke to start.


Did you clean the idle jets?
Did you actually take them out and look through them? Could you see daylight through them?


You had the tank pa

Looks like 1977-78 carbs with accelerator pump system.

You cannot blame this on the painter.

[MOONDOGNYC]

I wish you would tell us what year the bike is and if it is a CB750  or what.
A motorcycle does not have a body. It has a gas tank, fenders, side covers, and maybe a fairing. No body. IT is not a car.

You say you tuned the carbs. Then you say the choke is unresponsive in warm weather.
The choke is for cold weather, or just for starting when the engine is cold.
How can you say you tuned the carbs but yet you have no idea if the choke is connected?

The manual choke is not just an ON or OFF deal. Sometimes the engine only needs partial choke to start.


Did you clean the idle jets?
Did you actually take them out and look through them? Could you see daylight through them?


You had the tank pa

Looks like 1977-78 carbs with accelerator pump system.

You cannot blame this on the painter.

Sorry for the confusion Lucky...  My signature shows a 77 CB750F2.
 I truly appreciate all of the help the forum has provided as much as I do the inspiration to do the bike over.
   I do however disagree with your comment about the choke.  I am 50 years old and can assure you that in all of my riding years, NO manual choke has ever been for "cold weather" starting only. Maybe it is my motor, but it is pretty cold blooded. It likes the choke on an initial start where it has been left off for over 8 hours.  I also DID state that the choke WAS connected, just not working.
  Also, I have always referred to the tanks,fenders, etc.. as body work. Some use the misnomer "tins" from years gone by and some even go through the litany of "tank, fenders and side covers".  It's all good.

  Not really sure why you feel I am "blaming" the painter ? I blame myself for not cleaning out the tank once I got it back.
 Try to understand that when I say I tuned the carbs I used a mercury gauge and hooked them up to the carb ports. Removed the caps on the carbs and tuned them. Then I turned the air mixture screws on the bottom of the carbs until they were dialed in perfect. I rode it around with small lawn mower tank that I salvaged years ago from a throwaway and made sure it was cleaned out and had fresh gas. After it ran like a top, I put it away. Took it out the next day and rode it around my area again. Perfect again. I then rolled it into its spot and waited for the "body work" to come back from the painter. I DID NOT however, check to see if the tank was clean. I just hooked up the petcock, NO inline filter and tried to start it. The choke did nothing and it ran like crap.
  Fast forward to me taking off the crabs...lots of crap in the float bowls and the #2 carb overflow was blocked.  In my mind, it had to be the painted tank that delivered dirty fuel into the system.  Yes, my fault.
 I will be flushing out the tank tomorrow to make sure it is clean and then cleaning the carbs up...
  I will keep you posted. 

[motosan]

whatever is going on, and whatever the true cause of the issue might be, your ability to work so fast and come to find the issue is pretty amazing Moondog. 

That said....however, I MUST blame you for not posting the picture of the tank with the new paint!  Help your SOHC junkie friends here

[MOONDOGNYC]

Consider it done...

[motosan]

nice!  And I just realized that you DID post some pictures already haha.  So after all there is nothing to blame you for, but i will blame you for not directing me to the other post to save my face anyway

[MOONDOGNYC]

I graciously accept it...it usually takes a whole lot for me to tell someone to piss off....lol   

[Bodi]

RPM should go up with choke, but the mixture change doesn't cause it. There is a throttle advancer built in to the choke mechanism (at least I think I've always found one, but I haven't worked on that particular carb set in a long time). The adjustment procedure will be in the service manual. It's normal for it to be way out of adjustment after taking the carb stack apart for cleaning, the relationship between the slide adjusters and the idle setting can change on carb sets with 4 adjustable slide arms (the syncing adjusters): the choke throttle advance setting depends on the idle setting being about the same as before.

[lucky]

The bike is beautiful! Good job!

If you synced the carbs by turning the mixture screws that is a mistake.

When you sync carbs the mixture screws should already be set and they should all basically be exactly the same.

The sync procedure is setting the idle by getting the slides to all be open and getting the same amount of pull (vacuum). About 8-10 mb

You should not change the mixture screws after you have synced the carbs.

[MOONDOGNYC]

Got the carbs on. Cleaned everything. Very gummy inside the air cleaner and air cleaner tubes. 
  Need to tune the carbs and get it running smoother.
Still need to clean out the tank. Just trying to wrap my head around the best way to do it with the spanking new paint on it.

[motosan]

Just trying to wrap my head around the best way to do it with the spanking new paint on it.

see if Trojan Magnum fits around it?