Choke Tube Plugged in Bowl

[jrt]

I'm going through the carbs, trying to get my 1990 FJ up and running. I cleaned them and set them up according to David Raforth's instructions, and had no luck get the bike to fire up. The bike will start immediately using starting fluid so I've been thinking it's something in the carbs, especially in the choke and idle circuits.  I went back through everything several times making sure all the jets are clean, passages clear, float height in spec, etc and couldn't find anything. I eventually got the bike to run by holding my hand on the one or more of the carbs, totally restricting the air flow so that the engine sucked the gas straight up out of the carbs and the bike stuttered to life. After the bike got warm from me working the throttle and keeping it running at medium speed, I was able to get it to idle. But as soon as the bike would cool down I would need to go through the ritual again. It seemed to me that the choke was totally ineffective.

I inspected all the choke passages and tubes in the carb bodies of all four carbs - all clear. Then I looked at the carb bowl and the cast in tube (sort of like a well) that the body tube fits into. It had no flow in it. I saw a brass fitting down in the bottom of the tube and thought there must be some specific orifice that is drilled into it to meter the fuel, but after more cleaning, blowing with compressed air and poking with small wires (last resort) I've concluded that one of the POs plugged them on purpose. There is absolutely no flow through that plug, and all the bowls have the plugs in them.

So please advise. From reading David Raforth's carb interactions, it seems that the tube in the bowl should be open and free for fuel to flow. How else could fuel enter the choke circuit? I think what I need to do is drill out the plugs but wanted to check here before proceeding.

Here are some pics of the situation:





I appreciate any help and advice.

Jeff Theall

[fj11.5]

the hole in the tube recess is tiny, about 0.5 mm  , as I had one blocked on my carbs , bike had sat untouched for 4 years , with fuel left to dry out in the carbs, had cleaned everything except the choke ports in the bowl, , just one of the brass jet ? s was blocked causing her to POP and backfire , with choke on ,  , soak them with carb cleaner, overnight , , I used a welding tip cleaner to clear the blockage , and compressed air, , but not till. I swapped the float bowl for another one, , 

[jrt]

That's what I thought might be the case and I'm glad I asked. Fuel did sit in these bowls for a long time and all the other jets were extremely clogged up. I will clean-clean-clean until it opens and let you guys know how it turns out. Thanks.

[racerrad8]

As already stated, there is a microscopic hole to regulate the amount of fuel available to the choke circuit. Do not remove the plugs/restrictors as it will never run right after that.

The only true way to get the small orifices within the bowls and the carbs clean is the use of an ultrasonic cleaner.

Randy - RPM

[Pat Conlon]

Randy or David, do you know what the diameter of the hole is? I was wondering if a fine piece of piano wire would clear it.

As Klavdy would say....Don't want to bugger it up....

[FJmonkey]

Randy or David, do you know what the diameter of the hole is? I was wondering if a fine piece of piano wire would clear it.

As Klavdy would say....Don't want to bugger it up....

I prefer to use a nylon bristle, wire can scratch/score (bugger up) the inner wall of said tiny orifice. Gotta go, my petcock is calling me....

[fj11.5]

did you clean the emultion tubes , if she has sat with fuel in carbs, the holes in them would be blocked

[racerrad8]

Randy or David, do you know what the diameter of the hole is? I was wondering if a fine piece of piano wire would clear it.

As Klavdy would say....Don't want to bugger it up....

Nope. I have never removed the restrictor to check the size or clean.

That as well as several of the microscopic orifices within the carbs is the reason I bought an ultrasonic cleaner.

Randy - RPM

[andyb]

Small ultrasonic cleaners are commonly sold for dentures.  Hot water, a couple drops of soap, and you can drop small carb bits in to clean them with those.  Much cheaper than the great big units, just not nearly as useful because they're so tiny.

[SlowOldGuy]

You've got to get fuel through that orifice, or the choke will never work and the bike will act exactly as you describe when it's cold.  I've used a single strand of wire form a stranded 12 gauge electrical wire.  I don't think a scratch on the choke orifice is all that critical.  I'd rather have a scratched up port that flowed fuel than one that didn't.  It's not like you're running on the choke for extended periods of time.

I have had luck soaking the bowl then using Berryman's.  The straw on the Berryman's can is a tight fit to the port on the inside of the bowl.  Some were pretty stubborn, but just keep trying things until you are successful (short of drilling or removing the orifice).  Once it's clear, you'll see a tiny jet of cleaner blowing out of the tube.

DavidR.

[jrt]

Once I understood that there were definitely small orifices in tube and those needed to be clear, I just kept cleaning. I use an ultrasonic cleaner that I got off ebay to clean all my small bike and car parts so I just kept after it. That's the way I have cleaned my carb bodies and all the jets and they come out great. My issue with the bowls was that I had already run them through the cleaner a couple of times and there was no flow. Usually a couple of cycles is plenty to clean up clogged jets. Right now I have 3 of the 4 bowls cleared and I'm working on the last one. It is very stubborn. Gas sat in these carbs for a long time. The main needle jets were a clogged mess when I disassembled the carbs - brown crud all around them. So in retrospect, I'm not surprised that the choke tube wells are the way they are.

Here's my cleaner. I usually use a 20% Simple Green / 80% water solution.



The good thing about an ultrasonic cleaner is that there are no harsh chemicals needed for cleaning and it is safe for rubber parts. Carb cleaners usually have acetone and/or toluene and that stuff is nasty. I use the ultrasonic cleaner for brake parts too.

Once I get the fourth bowl cleaned, I think I'll go back through everything on each carb, reassemble and test. I'll keep you guys posted. Thanks for the advice and encouragement.

Jeff

[jrt]

After four days of soaking the fourth bowl in acetone and then running it through the ultrasonic cleaner, it finally unclogged. After that I went through all the carbs again, cleaning all the jets and bodies in the ultrasonic, then reassembled. Regular life got in the way for a while, but finally yesterday I got the carbs back on the bike. When I pressed the starter button, it only took two or three spins of the engine before it fired right up and settled into a very controllable, choke-on idle. I warmed it up for a few minutes and then set the regular idle too. After all the previous issues I had, it was very gratifying to have the bike run so well. It still needs adjustment and tuning but at least now I have something to work with.

Thanks for the help and direction.

Jeff

[fj11.5]

Wow,  that sure was blocked,how long had she sat for

[jrt]

Don't know exactly - a couple to several years. It came that way from the PO.

[jscgdunn]

You can also use heat to speed the process.  Use a,propane torch and warm up the bottom and side of the float bowl near the emulsion circuit.  Oce it cools off spray carb cleanerer through.  Be sure to turn off torch and do not smoke when using carb cleaner