=============================================================================== XJ CARBURETOR REBUILD TIPS =============================================================================== Once you get started you'll realize that it's easier than you envisioned. But here's a list of things to consider before diving in head first. This was posted on the XJ Owners Mailing List several times already so it can also be found in the MicaPeak.com archives. I thought it would be a good idea to dig it up and to make it more easily accessible.: =============================================================================== 01) Be patient and have a well thought out plan for keeping your parts together (eg. muffin tray, magnetic bowl, etc...). It’s very easy to lose something as small as a pilot screw o-ring or washer. 02) When you remove parts, always keep them in order so they return to the same carb... particularly the piston valves. Although the parts are theoretically identical, they're not. So it might be detrimental to interchange parts. 03) Get some pipe cleaners (soft brushes) to help you get into some of the crevices (a tootbrush can help too) 04) Don't forget to bench sync your carbs and check the float bowl fuel levels while the carbs are STILL OFF THE BIKE. It can certainly be done ON the bike but by now you’ve discovered how problematic it can be to pull the carbs out and put them back. You’ll find that bench leveling is quite a bit easier as long as you have a WorkMate (or similar) and a level and of course a float bowl fuel level gauge (which you can make yourself): http://www.maxim-x.com/fuel_level_gauge.html 05) You MIGHT want to CAREFULLY use an impact driver to free screws first because carb screws seem to strip more easily than most. But if you do use an impact driver, make absolutely certain that you brace the surface in question against a firm foundation because the impact might break off aluminum pieces if you’re not careful!!!!!! 06) It's helpful to deepen the slot in the head of your pilot screws while they're out - even if the slots aren't stripped yet. The deeper slot will make the screws easier to turn without stripping the slot if they ever stiffen or seize in the threads. 07) When you remove the pilot screws, don't go blowing any air down there before you also remove the spring, washer and o-ring - those are some really tiny and easily lost parts that are EXTREMELY difficult to replace. 08) When you replace (ie. put back) screws like the pilot screws, etc... a bit of anti-seize compound is highly recommended. The screws are brass and the threads are aluminum so there is an inherent potential difference that will always lead to oxidation just because of the dissimilar metals. The anti- seize compound will prevent that - but don't use so much that you plug up the fuel passages - be careful to coat the THREADS ONLY. 09) Remove the carb covers carefully so as not to tear the diaphragms beneath them. Sometimes previous owners or shops may have used some sort of sealant (although I don’t know why) between the covers and the diaphragms causing them to hold together. If the diaphragms tear because you’re too aggressive about pulling off the covers, it's a bitch to replace them. And even if you manage to, each one will cost you in the neighbourhood of $300. This is NOT a mistake you want to make. 10) When you remove the diaphragm assemblies, have a container of fuel ready in which to submerge and store the diaphragms. They should remain fully submerged in fuel while you work so that they remain hydrated. Otherwise they shrink and dry up and are more easily damaged – sometimes they also become difficult to re-install after they've shrunk and dried up. 11) When you re-install the diaphragms, there should be a notch on one side to determine orientation under the cover. Make sure the notch goes on the side it belongs and aligns properly before tightening down the cover. It won’t necessarily be easy to keep the ridge of the diaphragms in the matching grooves of the carb bodies but it has to be done to make a proper seal. To accomplish this it’s helpful to spray some tack spray into the grooves first. That should be enough stickiness to hold the diaphragms in proper alignment in the grooves before screwing the covers back in place over top of them. 12) Although you'll have to pull the carbs from the bike, don't separate the carbs from the rack or you may end up with throttle shaft problems and more work than you planned. In most cases it's not necessary to separate the carbs from the rack so don't do it unless you already know you need to replace throttle shaft seals. Avoid separation if you can. 13) Avoid removing the throttle plates from the throttle shaft because getting them aligned again later isn't always as easy as it looks. You may find that they tend to bind afterwards despite your best efforts. It's better to leave them alone since it’s not likely they’ve moved to begin with. 14) I like to stretch the various springs (diaphragm, starter plungers) until they're equal in length - it's just a preference to achieve as much equality between carbs as possible. But, be careful because excessive stretching might cause too much resistance later on and might effect carb performance. 15) If you find some screws to be stiff (ie. don't spin freely but require extra force), soak them with penetrating oil for a while beforehand if you can. The longer the better (several days can't hurt). 16) Wherever you remove brass screws (ex. pilot screws, jets, etc...) always find a PERFECTLY FITTING screwdriver before you start. Buggering up the slot head with the wrong tools isn't a good way to get started. Actually, this also applies to non-brass and non-slot screws as well. They can all be damaged by using the wrong size screwdriver, particularly when you have to apply additional force... but the brass screws are most susceptible to damage under these conditions. Don't be in a hurry. Take the time to find the right tool or you may come to wish you had. 17) When you reinstall the piston valves, don't use any lube on them - it's not helpful and will actually prevent free motion. In combination with dirt and dust, lube also tends to cause the piston valves to bind in their bores. 18) Don't use any gasket sealer ANYWHERE in the carbs (ex. carb covers, float bowl gasket, etc...). It's not necessary and will only cause you grief when the fuel dissolves the sealant and turns it into a gooey mess to help plug up your newly rebuilt carbs. It will also mean you’ll be replacing rather than reusing gaskets the next time around. 19) It's helpful to have a second set of hands to get the carbs off the bike but more so to get the carbs back in again. With old intake boots it can be a real bitch sometimes because of the lack of flexibility of the rubber. 20) Be especially careful when attempting to remove the float pins. They should slide out with a slight tap with an awl or punch in the centre of the correct end of the pin. If you need to apply more force to get the pins to move BE VERY VERY CAREFUL how and where you apply that force because it's all too easy to break off the float support posts. They're cast aluminum and it doesn't take too much effort to snap them off. I can't stress enough how careful you must be when removing those pins. If they don’t come out easily, here’s a video that shows another method: http://www.maxim-x.com/pix/carbs/floats/x_float_hinge_pin_removal.mov 21) When you disassemble the float valves, if the float screens are still present, be careful when you remove them. They have pretty fragile plastic edges that are easily broken but not so easily replaced. They also have a tendency to go flying and vanish forever. Often you'll see carbs which are missing some or all of those screens and it's usually because someone (probably a shop) ignored this particular tip. 22) It's pretty easy to lose track of which carb is which when you're engrossed in cleaning them and have flipped them all around more than once. I find it helpful to put some masking tape on somewhere to mark the front and #1 otherwise, if you're not paying attention, you may find yourself adjusting the #4 float after you find that the #1 fuel level is out of whack. I've seen this in action a few times now. It can really slow down the process. 23) While you have the float valves apart, you may be able to save the cost of replacing the float needles or valve seats or both by taking the time to polish the valve seats using the “Golf-Tee” method. The tip of a wooden golf tee in a drill press with some polishing compound will polish away any imperfections in the valve seat and will also relocate the point of contact with the float needle to a new and unused spot on the rubber tip of the float needle. Usually that’s enough to save the cost of replacing either part. 24) When you attempt to reinstall the carbs, it's helpful to have a heat gun or hair dryer handy to soften the airbox boots to help make them more flexible. Some have said that a bucket of hot water is good too and although it does work to submerge the boots ahead of time, they cool off and stiffen up again very soon after leaving the hot water. Personally, I don't find the hot water method to be too useful for carb boots because of the time involved in getting the carbs into place again. 25) I’ve found it to be helpful to securely clamp the airbox boots to the back of the carbs BEFORE trying to install the carbs on the bike. Those who have removed & replaced Maxim-X carbs before will have noticed that the old rubber airbox boots tend to change shape over time making them hard to clamp into place if the carbs are already back on the bike. The tendency is that the tightening of the clamp at the top causes the clamp to slide and pull the boot off the bottom. It’s very difficult to get your hands and tools onto the clamp to keep it and the boot in place as you tighten. It’s MUCH easier to do the clamping BEFORE the carbs are back on the bike and it might even be helpful to use some spray tack on the carbs to help keep the boots from sliding off. 26) As you reinstall the carbs, it can be helpful to first grease the manifolds and the boots where they meet the airbox. It will help the carbs snap back into place without having to apply as much force to get the job done. But, DON'T USE A PETROLIUM-BASED GREASE - it will break down the rubber. Use something like plumbers grease which is silicone-based and won't harm the rubber boots. And whatever you do, DON’T apply any grease to the BACK of the carbs on which the airbox boots will be clamped. That will only make your life miserable when you try to clamp the airbox boots onto the carbs and find that they constantly slip off. Learned that the hard way. =============================================================================== If anyone has still more helpful tips that should be added to this list, please contact me to amend the list. I'd like to make it as complete as possible. HAP webmaster@maxim-x.com