I told AF79 I would assemble an instruction for rebuilding the ES/SX/350X carbs so as I put this information together, I will do it here. This will benefit everyone who wants to do the work their selves. Right now I'm out of ES/SX carbs to use as illustrations so I will be using a 350X carb for this purpose. I have fours carbs inbound and hopefully at least one of them will show up before I finish with this instruction. In any case, when one does show up, I will post illustrations.
Please do not post to this thread until I say so. I want it to flow without posts in-between. When I do get it finished then by all means post away but for now just standby.
First of all, lets look at the differences between the 85 and 86 rebuild kits. I have use a few different kits over the years and they are all basically the same but lately I've been buying Shindy kits from RJATV on Ebay. About $18.00.
1985 Kit Inventory
Bowl Gasket
Top Plate Gasket
Float Valve
Pilot Screw
Pilot Screw Spring
Pilot Screw Flat Washer
Pilot Screw Oring
Needle
Needle Jet
Needle Jet Clip
Main Jet #130
Slow Jet #38
Primary Jet #45
Bowl Rim Oring
Drain Screw Oring
1986/87 Kit Inventory
Bowl Gasket
Top Plate Gasket
Float Valve
Pilot Screw
Pilot Screw Spring
Pilot Screw Flat Washer
Pilot Screw Oring
Needle
Needle Jet
Needle Jet Clip
Main Jet #130
Slow Jet #38
Startup Jet #70
Primary Jet #45
Drain Screw Oring
Idle Knob Spring
Idle Knob Bolt
Idle Knob Washer
As you can see, the two kits differ by six parts. The absence of the bowl rim oring does not effect the carb operation. If you look at the bottom of the linkage cavity you will see a drain hole. That hole continues through the bowl. The oring provides a seal between the linkage cavity and the outlet on the bottom of the bowl. Its job is to provide a leak path to drain the linkage cavity if it gets filled with water.
The other differences are pretty obvious. Honda redesigned the jet stack in 86, they integrated a screw in type startup jet with a larger hole fixing the cold start issue the 85 carb has. The 85 startup jet was pressed in. There used to be a kit to fix this problem but if the jet is removed, drilled to .80mm and reinstalled then the cold start issues go away.
So this is where I start now that the kit differences have been outlined. An 86 kit will work in an 85 carb but you will be short the primary jet and bowl rim oring but you will get the idle knob hardware.
On the rim of the body just under the fuel inlet nipple, there is a number identifying the carb. Here is the breakdown of the numbers and their application.
QA01A - 85ES
QA02A - 85SX
QA04A - 85 TRX250 (this carb will not allow the ES or SX to run right)
QA05A - 85 350X
QA07A - 86/87ES
QA08A - 86/87SX
QA09A - 86/87 TRX250
QA10A - 86 350X (nobody makes a kit for the 86 carb and the slow jet is larger for 86 #45. If you put an 85 slow jet #42 in an 86 carb, the motor will run very very lean at idle to the point where the head pipe will glow. Be aware of this)
I will continue this tutorial tomorrow. Please no posting yet. thanks.
To elaborate on the 85 ES/SX cold start problem I mentioned. This mod only applies to the 85 ES/SX carbs and is really only a problem for you in really cold environments. In a nutshell, because the startup jet metering hole is so small, it doesn't provide enough fuel to fire a cold soaked motor but I'm talking 30deg F or colder. None the less, it couldn't hurt to do this mod no matter where you live. I have attached the original Honda Service bulletin along with pics of how I pry the jet out. You want the modified screwdriver to be about horizontal. Gently push down and the jet should come out. I use a .80mm micro-drill and a Dremmel to drill it out. I have encountered many ES/SX carbs where the startup jet was plugged with debris. You will need a #4 sheet metal screw, a modified flat blade screwdriver and anything with about a 1/4 - 3/8 diameter to lay on the jet stack to act as a pivot. Screw the sheet metal screw in about 1 - 1 1/2 turns. Don't worry about damaging the jet with the screw. The metering hole is farther down than the screw will reach. Pry the jet out, drill it, and reinstall. While the jet is out, be sure to shoot carb cleaner through the hole. If doing a carb rebuild, leave the jet out until final assembly. A set of metric micro-drills can be found at most local tool stores or on the internet for just a couple of bucks.
I have a set similar to these. You will need a Dremmel with a chuck to use these.
Lets continue with the initial disassembly. For this I'm using a TRX250 carb but the ES/SX/X carbs are the same.
The very first item I always remove is the pilot screw. The reason is if the pilot screw is seized, it will more than likely snap the head off and that may dictate whether the carb is tossed. If the head does snap off you have a couple of options.
1. Drill the screw and try to extract the pilot screw with an easy out
2. Cut a slot in the pilot screw and try to use a flat blade screwdriver to turn the pilot screw out
3. Use a large drill and drill out as much of the pilot screw as you can. If you use this method you run the risk of damaging the thread in the carb body
With any of the three methods, applying some heat is always good but keep in mind the carb body is cast aluminum so you don't want to make the metal glow, just heat it. I could do an entire thread on the pilot screw extraction methods so for the purpose of this thread, I will assume the pilot screw came out ok.
Tools needed
#1 Flat Blade Screwdriver
Pick with a fine tip bent with a hook or something similar (This is to get the flat washer and oring out of the hole)
Remove the pilot screw, spring, flat washer, and oring. Be sure these parts come out. I have seen carbs with no flat washer and oring so take a flashlight and shine it in the hole ensuring all the parts came out.
None of these parts will be reused but set them aside until the rebuild is complete.
Remove the vent hoses and bowl drain hose. Turn the carb on its side and remove the cover if not off already and idle adjustment knob. Set all the parts to the side.
If you have the need to chase the pilot screw hole threads or the choke valve hole threads, Wonderboy has determined the tap needed is a plug tap 6mm x 0.5 and they are available online.
The next part to disassemble is the top of the carb.
Tools needed
#1 Phillips Screwdriver
#2 Phillips Screwdriver
Remove the three screws retaining the top cap. Remove the cap and old oring and set aside. Next remove the #2 Phillips screw and lock washer retaining the actuation arm to the shaft. Now it's time to remove the two #1 Phillips 3x6mm pan screws holding the linkage to the slide. These screws like to corrode to the slide. You basically have one shot at getting them out without boogering the heads. To do this, I set the carb on a firm surface. I take the #1 Phillips screwdriver and set it on the head of the screw. Now push down firmly as you apply torque to loosen the screw. Steady even pressure and the screw should break loose. If you booger the head then the only recourse is to drill the head. Not a good option so be careful. Also keep in mind the slide has a Teflon coating to allow the slide to move freely without any lube. Protect the slide. Once you get the two pan screws out, remove the slide and linkage and set all the parts aside.
Remove the drain screw
Remove the oring on the drain screw
Remove the four #3 Phillips screws retaining the bowl
Separate the bowl from the carb body
Remove the old bowl gasket
Remove the old oring on the rim of the bowl
Ok now we're to the meat of this rebuild but I would rather have an ES/SX carb to illustrate from. I have an ES carb coming in from Colorado but it won't be here for a few days so I am going to pause right here until it comes in. I'd rather not pull my carb and disassemble it but if any one of you has an ES or SX carb that is complete and are willing to take several pics I can use for illustrations then I have no choice but to pause here. If you do and are willing, shoot me an email to jamesbaldwin99@gmail.com and I'll let you know what pics I need for completing the disassembly. I have a couple of pics of an 86 carb to illustrate the jet stack with but not the right pics for the 85.
Thanks to Wonderboy A.K.A Frank and his camera I can finish the disassembly. In my last procedure I removed the bowl, now let's get the float and jets out. As you can see in the first pic, the bottom of the carb with the jet holder (Baffle), float, and the jet stack. The second pic shows the jet holder removed and the third shows the float, float pin, and float valve removed.
Now lets remove the jets. I didn't ask Frank to remove the jet from his carb but I will illustrate each jet and their position. Removing them is pretty self explanatory.
Remove the main jet
Remove the slow jet
remove the primary jet
If your doing the cold start mod, remove the startup jet per the instructions in post #3.
Remember I said in 86 Honda redesigned the startup jet. If you look at the side of the jet stack you will see a hole up toward the top of the jet stack just above the startup jet. In 86, Honda put a screw in jet. If you're working on an 86 carb, remove the rubber block off plug and screw in startup jet. The same goes for the 350X carb. If your 86 carb does not have a rubber block off plug, don't worry, the hole its blocking is not through drilled. To tell you the truth, I'm not sure why Honda put a rubber plug in that hole.
Think I'm done with disassembly? Not so fast. There are still three parts to remove.
Needle Jet Holder
Needle Jet
Main Nozzle
Unscrew and remove the needle jet holder with a 7mm wrench and set aside
Using a small punch or small drift, come down through the slide hole and push out the needle jet. It will fall out of the needle jet holder hole.
With the primary jet removed, reach in with your finger and push the main nozzle down. It should fall out of the primary jet hole. I don't have an extra main nozzle to illustrate but when I get my carb, I will insert a pic of it.
So that pretty much completes disassembly. I don't remove the butterfly, butterfly shaft, or spring. They are a total drag to reinstall more specifically getting the spring set and wound correctly so I leave them in.
I am going to wait until my carb gets here before I get in to the next set of procedures as I will be actually doing a rebuild on it so this is a good time to field any questions you may have concerning the disassembly.
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