ANDY'S CARB CLEANING GUIDE - REV 1.DOC APRIL 04, 2012 L:\000 - Files\Motorcycle\1984 V45 Magna\Carbs\Andy's Carb Cleaning Guide - Rev 1.doc Page 1 of 7
Don t worry about the lost first page it is a BS computer glitch so I inserted a blank one to be lost the article starts here: Carburetor Cleaning Guide (Revision 1 May 2013) Carb cleaning just the phrase alone is enough to make a V4 owner blanch and break into a cold sweat but it doesn t have to be. Any DIYer who understands why a wrench isn t for use as a hammer and what the difference is between a screwdriver and a pry bar can successfully clean their own carbs with care and attention to detail. Some inexpensive tools and supplies are need but beyond that there is a fairly simple recipe to be followed and a few basic precautions to be observed. Carbs function as part of the entire combustion system and interact closely with the other parts of the system. To get the best performance from your bike, carb cleaning needs to be part of an overall tune-up process. To minimize the amount of time it will take to get your bike into good running order it is necessary to do each step in order to establish the correct conditions for the next step. Doing the steps out of order will not produce the same results because of the interaction between the parts of the system. I encourage you to take pictures of each step to serve as a reference when it is time to re-assemble the components. This is especially useful for cable routing and linkage connection reference. I have inserted an icon where I think a picture may be helpful. This guideline is based on my 1985 V45 Magna but is general enough to be widely applicable. I have inserted an icon where I think models typically vary. Whenever you take your carbs apart check that the front and rear carbs have the right parts in the right places. In the past I have recommended doing one carb at a time so as not to mix the parts no longer since it occurred to me that there is no guarantee that some skeezix shop or previous owner did not mix them up already. You need to actively determine if they are in the right carbs, not just assume that putting them back where they were is right. Things you need to know before cleaning your Carbs (differences between the carbs) Before cleaning or rebuilding your carbs you should be aware that there are similar looking parts in different carbs that have easy to overlook but critical differences. Whenever you take your carbs apart check that the front and rear carbs have the right parts in the right places. In the past I have recommended doing one carb at a time so as not to mix the parts no longer since it occurred to me that there is no guarantee that some skeezix shop or previous owner did not mix them up already. The smaller jets, thicker needles, and larger springs go up front, the larger jets, thinner needles, and smaller springs go in the rear. This acts to run the rear carbs with a slightly richer mixture to use fuel cooling to compensate for a reduced airflow cooling of the rear bank of cylinders. Page 2 of 7
The emulsion tubes with the holes furthest from the threads go into the rear, the emulsion tubes with the holes closest to the threads go in the front. This is due to the different mounting angle of the carbs. The needles are designated by 3 letters - the 3 letters represent taper, length and diameter. The higher the letters, the bigger the needle s size. The jets are designated by 2 or 3 numbers - 42 = 0.42mm diameter, 128 = 1.28mm etc. Carbs are clean when they are clean where you cannot see, not when they are clean where you can see - then they are just pretty. The Carb Cleaning Recipe The tune-up steps: 1. Before removing carbs; a. lift gas tank (make sure not more than 2/3 full), b. remove air filter, filter box, metal screen under box, c. drain and remove the radiator, d. remove heat shield mounted on the air box on the radiator side, e. turn the fuel petcock off, f. remove the gas line from carb #1 and catch gas in a container. 2. Removing carbs; a. note orientation of the isolator (rubber boots) clamps and loosen all 8 of them, b. pull the carbs and airbox upwards until loose (difficult by hand - try ONE tie down threaded under the airbox and over the top of the frame or anchored to the handlebars accompanied by hand pressure back and forth on each side) until the carbs come loose as a single unit, c. remove the isolators and clamps, d. wiggle, tilt, and the slide carbs to the left side of the bike, e. note the cable routing and disconnect the choke and two throttle cables, f. undo the single clamp bolt (8mm) holding each of the two coolant crossover tubes, g. work each tube straight out of the heads. With the clamp removed they are only held by the o-rings on each end. If you pry them be gentle they are thin walled, and pry each end equally so they don t twist and jam. If they jam, gently push the out end back in level with the other and then continue. Don t be rough if you distort the ends you will have trouble getting a leakfree re-installation, h. remove the carbs out the right side of the bike. Some twisting and tipping may be needed but force isn t necessary unless you are doing something wrong, i. with carbs off the bike, drain any remaining gas from them. 3. Before disassembling the carb-airbox unit; a. Note which carb is which carb number. The carb for cylinder #1 is carb #1. On my bike Cylinder #1 is rear left, #2 is front left, #3 is Page 3 of 7
rear right, #4 is front right. b. Prepare a container for each carb and the pieces removed from that carb a plastic tray is excellent but a separate area on the workbench is sufficient. Do not mix the parts between the carbs as there are subtle but critical differences (see previous section). Label each container with the carb number. c. Prepare an additional common container for linkages and other external parts, d. Note which carb number fits where in the airbox. If you want, use a marker to label the inside of the airbox. 4. Disassembling the carb-airbox unit; a. Start by removing the 2 screws (Phillips #1) per carb from the inside of the airbox. If you use an impact driver be careful not to damage the thin wall casted body of the airbox, b. Separate the carbs as a group from the air box and lay them on the bench, c. Remove each of the rubber trumpets and place it in the appropriate carb s container, d. Carefully note how all the linkages and connecting tubes run. Pictures are a definite plus here. Consider using paint marker dots to identify which end or face is oriented where if this is your first time taking them apart. e. Disconnect all the linkages and connecting tubes, placing the springs, washers, nuts, etc. into the common container. f. At this point, I like to use a 1/8 drill bit to mark the carb number on each carb body by drilling a slight dimple pattern in the carb body as shown at right. Be sure that you do not drill into any passageway or you will ruin the carb body. The location shown is a safe one. 5. Disassembling each carb; a. Slider - Remove the 3 Phillips screws from the domed chrome top hold the top in place against a light spring pressure while removing the screws. Before moving the top, look carefully around the edge and note where the little raised channel is located. b. Lift the top off, remove the coil spring and place both in the container, c. The black rubber diaphragm is delicate and EXPENSIVE treat it with care while removing it along with the slide and main jet. Put the carb down and hold onto the slide, Page 4 of 7
d. Remove the needle from the slider by pressing down on the plastic piece inside the bottom of the slider and turning it 90 degrees. It should now lift out, releasing the needle. Make a special note of any washers under the head of the needle and remove them with the needle, e. Place the slide with diaphragm in a protected place a dedicated margarine container within the carb container would not be going overboard. f. Float bowl - Turn the carb over and remove the 4 screws holding the bowl. The bowl will likely be stuck in place, very gently pry it apart taking care not to damage the mating surfaces or the float bowl gasket. Inspect the gasket, if it damaged or flattened so that it does not protrude above the mating face of the float bowl, it needs to be replaced, g. Note the orientation of the float and use needle-nose pliers to pull the float pivot pin completely out, removing it and the float, h. Remove the float valve, screen, and washer from the carb body under where the brass tang of the float sat, i. Remove the main jet (slot head), main jet holder (hex body), and the slow jet from the carb body. One piece is pressed in and is not removable, j. Choke Remove the nut and washer from the top of the activating shaft for the choke. Pull the black plastic tube up and off the shaft, loosening the lower portion of the shaft. Unscrew the plastic nut around the choke plunger rod and work the shaft forks out of the groove on the end of the plunger. Remove the activating shaft, plastic nut, and plunger. Hopefully yours will not have the woodscrew added by a creative PO to replace the brass nub on the end of the enrichner valve likely broken off during an incorrect disassembly attempt. k. Butterfly valve Note the location of any markings on the round butterfly valve it has a top-bottom and insideoutside orientation that must be maintained when it is reassembled or it will not fit or operate correctly. The valve is secured to the throttle shaft by two small Phillips head screws. It is essential to have a #3 Phillips screwdriver that fits the screw heads tightly or they will be stripped when you try to remove them. The other end of the screws has been slotted and spread apart slightly to ensure they do not vibrate out of the throttle shaft. Remove the screws, l. Turn the throttle shaft 90 degrees and pull the butterfly valve out, m. The throttle shaft is now free to be removed, n. Around where the throttle shaft enters the carb body there is a pressed in metal ring covering a felt seal. Use a small screwdriver to remove the ring and washer without damaging either of them. The seal Page 5 of 7
can be damaged by the cleaners and is no longer available as an OEM part possibly not as an aftermarket part either, o. Pilot needle jet The pilot jet screws into the outside of the throat of the carb near where the isolator (rubber mounting boot) stops. It may be covered by a thin aluminum plug pressed into the hole over the pilot jet or more likely, that may have been removed during a previous cleaning. If the plug is there, remove it by drilling a small hole through it and inserting a dental pick or wood screw and pulling the cap out. Discard it. p. Under the cap is the jet. Use a small slot screwdriver to screw the jet IN until it bottoms gently, counting the turns to the nearest 1/8 th turn. Record the number of turns for use later they can be different for each carb so do not mix them up, q. Unscrew the jet and remove it along with the spring, washer, and o-ring. If the washer and o-ring do not come out it is necessary to hook them and pull them out with a small piece of copper wire or other soft hook that will not damage the seat. r. If you haven t done it already, now is a good time to order any replacement parts you need. (The screws for the float bowls and diaphragm housings are size M4x0.70 pitch. length is about 1 inch for float bowls and.75 inch for diaphragm. Do not use longer screws as those for the carb bowl will hit and crack the plastic fuel transfer tubes. Carb mounting screws are M5x1 about 1 inch long.) s. Record the numbers stamped on the jets and valves along with the carb number they were found in. This information is for future use such as determining if you need to re-jet after changing air filter or muffler type or for diagnostics when having carb problems. 6. Cleaning each carb; Washer and o-ring are still in here and must be fished out Ultrasonic cleaners are excellent for cleaning carbs but are usually to expensive for a DIYer to acquire for occasional use. The next best way for a DIYer to clean carbs is to buy a gallon of carb cleaner and be ready to soak the metal parts in it using a basket or strainer. Spray carb cleaners are useful for cleaning the inside of small passageways in the carb after it has been soaked. Carbs must be disassembled for cleaning. Never put carb cleaner directly onto rubber, plastic, or felt carb parts as they can be damaged and ruined by it. They can also be damaged by spray carb cleaners. Soak all the metal parts for one carb together for 8-24 hours then rinse them with water and dry with compressed air. When doing this, take appropriate precautions to avoid blowing them into Alice s rabbit hole where they will live forever. Use spray carb cleaner to blow through each passageway make sure that it emerges somewhere and that the passageway is clear. Page 6 of 7
7. Before installing carbs a. make sure the fuel filter is clear and the tank(s) do not contain rust or sediment (so you don't have to clean the carbs again in 2 weeks), b. make sure that the valve clearances are correct (so each cylinder can breathe freely and evenly), c. bench synch the carbs (to get air flow thru carbs roughly equalized), d. set pilot screws about 2-1/2 turns out on each carb (to get mixture roughly right), 8. After installing carbs a. make sure the air filter is correctly installed and is clean (to allow correct air flow to the carbs), b. on-bike carb synch (to finely balance the air flow across the carbs), c. adjust pilot screw on each carb using the idle-drop method (to match fuel volume to the air flow volume), d. make sure that the hand grips are secure (you will need to HANG ON!). Magna carb mounting boots (isolators): The V65 is 36mm (1.42") and the V45 is 32mm (1.25") You can get fuel filler neck hose in both sizes and the ultimate is 1.5" or 1.25" silicon hose. If you are having trouble finding the hose, one possible source for this hose is a local farm equipment dealership. Do not get the hose with the wire reinforcing or installing your carbs will be a special kind of challenge! These should be done in the order listed and do not skip any steps. There is no such thing as a shortcut when cleaning carbs - they just lead to do-overs! Example: if you skip step #2 and the valve clearances are off, then the on-bike synch will not be correct, so then the mixture setting will be off,so... do-over. Happy in Hondaland, MagnAndy Brampton, Ontario, Canada When one removes the o-ring gasket, there may be a few noticeable traces of something that the factory used to keep the gasket in place while positioning the bowl. I usually do not need to use any gasket sealer material to hold the o-rings in place even for the non-preformed ones but if necessary, I use a TINY dab of silicone in a few places, to hold the gasket in place in the bowl cover groove. It works like a charm. Just make sure your dab is very little, and dabbed toward the outside of the bowl groove. Do not get much, if any on the inside of the gasket or housing, because fuel will dissolve it and cause problems when it gets into the bowl/jets. That was my mistake on the first carb pull. Page 7 of 7