Carb Removal and Rebuild ( ST1100 )
PART TWO:Now that the carbs are out, I always drain the float bowls into a clean container to see what, or if, anything comes out. I used the tailgate of the truck as a work bench to drain OUTSIDE in a well ventilated area. As you can see in my pic’s, the bowls are full of debris. Trouble....
The outsides of the carb bodies are filthy and need a good cleaning. Now is the time to do it. I used a whole can of carb cleaner and a blow gun / air compressor to clean them up. See the difference? Always start off with clean outsides so none of the junk gets into your cleaned carbs. Cleaning them will also help with the linkages, etc.
Now that the carbs are drained and cleaned, I can take them inside to the shop and start dis-assembly. First thing I’m going to do is mark EVERYTHING with it’s prospective cylinder #. Some thing’s I’m going to replace. Most of it will be returned to it’s original carb body, keeping all of the original factory mating surfaces the same. You’ll see I've also marked everything up top on the plenum and the intake snorkels. The top side is also coming off. Some guys don’t, but you’ll see why later-on that it’s best to remove it.
I started with taking off all of the float bowls. YUK! I’ve done countless carb rebuilds, but have never seen anything like this. Funny thing is, that the bike ran great, right up to the point to where it wouldn't.
After the bowls are off, I removed all of the floats and checked to see if there was any leakage. Shaking them to see if there was any gas on the insides. All checked OK. I cleaned them and set them aside. I also took a real good look at the float needles. Many times the rubber tip gets worn and grooved. LOOK THEM OVER GOOD. If grooved, throw them away and get new needles and seats! Surprisingly, mine were OK and cleaned up well. I take a shop cloth and spray carb cleaner on the towel, then gently twist the tip of the needle in the cloth. Cleans them up well.
Next, I remove ALL of the jets. Float seats, idle mixture, slow speed / pilots, main jet and emulsion tube’s. Check the screens on the Float needle seats. Clean as needed. I have both a homemade idle mixture screw tool and a Honda factory tool. Homemade one gets used on the bench. I counted the screw turns from lightly seated. All were between 2 and 2 ½ turns from the factory. It doesn't matter to me what they are, because I will be doing a jet change and the idle drop procedure when done.
Now that all of the bottom side is disassembled, I’ll move to the top and take all of the upper components out. I start removing the diaphragm’s / slide’s and inspect the slides for wear. Also looking at the rubber diaphragm’s to see if they are in good shape, not torn, or dry and brittle. Mine checked out OK, but had some weird white stains on them. Probably from sitting for a long time. Most of it cleaned up. Also have a look at the needles to see if they are worn / scuffed from possibly rubbing.
As you can see here, it is important to check and replace the secondary air breather filter regularly, just in front of the air cleaner assy. The breather filter on this bike disintegrated and filled the upper diaphragm chamber’s with foam filter material. Which also means particles went down into the carb vent, air-cut valve assy., choke vent and slow speed vent.
I now have a nice pile of carburetor parts. All numbered and placed separately with each corresponding cylinder number.
As mentioned earlier, some guys don’t take the upper plenum / tube assy. off when cleaning their carbs. It is relatively easy to remove it, but a pain to re-install. My opinion is that it must come off, or damage to the air-cut valve diaphragms, sooner or later, WILL happen. I've worked on quite a few bikes that were having fuel economy, idle speed, drivability and “running rich” conditions. All do to the “Shade Tree mechanic” destroying the air –cut valve diaphragms with carburetor cleaner, by NOT removing them. To get the air-cut valves out, the upper plenum must be removed.
Also take note that the plenum mounting screws are #3 Phillips. Using a #2 may work, but more than likely they will strip out. The screws are tight from the factory.
You’ll notice here that there are centering dowels on the bottom of the plenum. The screws go down through the center of them. Sometimes they fall out and get lost. Use caution when lifting up the plenum.
There are 8 dowels. I circled the locations in the carb bodies the best I could.
Now that the plenum is off, I can remove the air-cut valves. Sort of a challenging task, but can be done without breaking the carbs totally apart (major pain). I’ve taken the ST carbs totally apart once and vowed to never do it again! Linkages, springs, tubes, alignments, o-rings, etc.
There are two valves facing on the outer bodies of the carb’s. I take them off first. Then move onto the inner ones.
The inner valves upper screw can be removed with a #1 Phillips at an angle. Lots of inward pressure is needed so the screw doesn't strip, but breaks loose easily. For the lower screw, I use a 90 degree Phillips. Trust me, it can be done. I have to hold the throttle linkage out of the way for access. I used an old license plate wrench to hold the linkages open.
Check the diaphragms for dry rot, cracks, condition, etc... There are o-rings that will stick to the inner body of the carb. Don’t loose them...
I now have totally stripped carbs and ready for cleaning.
