https://ia800204.us.archive.org/14/...ice-manual/yamahavmaxvmx12-service-manual.pdf
Print-out a copy and place it in a 3-ring binder for the shop. Save this under your computer 'favorites.'
Use the search function to find threads on the subject you need to work-upon. Then read the service manual on it. Printing-out pages will help you to have a handy in-front-of-you 'how-to-do-it guide.
There are many threads on doing things like a carburetor service. If you decide to undertake things,
take plenty of pictures! Your work will go much-more smoothly if you do.
Some things you may need to replace are available at your local automobile supply store. Among those are the thermostat, fuel filter, thermocouple for the cooling system, various bulbs, and the oils and coolant. For the coolant buy a name-brand which is compatible with aluminum engines. See whatever coolant color you have in-there, and check to see if the coolant at your local store matches it for color. If you decide to ride the bike as-is, and it needs coolant, use the same color coolant to top it-off. Using a different coolant color may cause a precipitate to form, the coolant can crystallize, and plug-up things in the radiator or the engine coolant passages! That is nothing you want to deal with.
Let us assume for now, the coolant is OK, and it doesn't need topping-off. You checked the coolant valve on the front of the engine, and after consulting the service manual, the valve is positioned properly. You start the engine, and you find you have a coolant leak. You may be able to tighten the clamp and stop it.
If you decide to drain the coolant and re-fill it, flush it first with fresh water. You can use tap water because the water isn't going to stay in there very long. Run the bike until the temp gauge goes to the 3 o'clock position. Either ride it for a bit, or let it idle for a few minutes and when it's off, drain the coolant. Use a catch-basin and see if anything comes-out with the water, something looking like crystals in a clump means, 'flush it again.' You need to repeat flushing with fresh water until the water drained out is clear, and no sediment or crystals.
Be sure you follow the coolant valve instructions to remove air pockets in the coolant circulation. The coolant overflow tank should be about half-full when it's been 'burped' (that coolant valve, remember?) and the temperature gauge should run at the 3 o'clock position under normal use. It can go higher, and at times like a hot summer day, stopped in a traffic jam, the needle may approach the 'red-zone,' but it usually will stop as it approaches that. You should hear the radiator cooling fan kick-in if the coolant temperature gauge climbs. That's what you want. A reminder, use the service manual to become thoroughly-familiar with whatever you want to work-upon. Read the threads about it. Print-out copies from the service manual and the threads you find relevant to the work being done.
Take pictures! Take your time, and you should find yourself able to do many things on your own. If you have a more-experienced buddy who can assist you, all the better. If you come to a point where you are stymied, post a question here, and people will help.
The service manual will help keeping things straight. You can also use your local Yamaha dealer's help in ordering things. Many people on here are selling used parts, as your bike may have something which needs replacement. Check the classifieds here. I use Ron Ayres Yamaha here in the USA to order parts, Look at their websites for the parts fiche. The exploded diagrams of whatever you need to work-on help you to see what needs replacement. Things like O-rings and gaskets are usually '1-time-use,' meaning, when you disassemble things, you need to use new replacements to ensure that the brake fluid stays in the hydraulic systems for thee front brakes, the rear brakes, and the clutch system. Use DOT 4 fluid for filling them. Brake fluid is harmful to paint finishes, have plenty of clean dry towels (paper towels are ok) and immediately wipe-up any spills, especially on painted surfaces.
A word about parts fiches, some dealers' websites may have better exploded diagrams (sharper pictures, more-clear and easier to understand) in their fiches than others. Compare prices, and I suggest that factory Yamaha parts are the best, especially when it comes to things like the brass bits in your carburetors.
Do not buy the ebay 'all four carbs in one kit' sets! They are trouble! As one of our POTUS (President of the United States) wives once-said,
'just say no' to the kits. They don't fit, they are the wrong pieces, and our website has plenty of people who learned the hard-way about this.
That said, there are some aftermarket suppliers which can substitute for the OEM (original equipment manufacturer) parts. K&L is an aftermarket supplier for carburetor pieces and All-Balls has various bits like steering head bearings and seals, and wheel bearings and seals kits. In the end, you can't go wrong with Yamaha factory replacements, though you may pay more.
I'll include some threads and pics to help you understand the things discussed here. A reminder: the factory service manual has an Appendix which contains many useful pages. Routing of the throttle, clutch, and brake hoses is shown. Before you disassemble anything, make sure that you understand the process. I will use masking tape and a fine-point Sharpie pen with permanent ink to label pieces and where things are supposed to go. I use different sized baggies to hold pieces. I use a piece of cardboard to punch holes into for the various side covers for the engine, to insert the machine screws so I don't lose them. You can make a shape of whatever cover you're removing to show which screw goes where, on the cardboard. Refer to the parts fiche when you do this as there may be rubber washers on screws at the bottom of the side cover. If you don't replace the screws with washers in their proper locations, you will have leaks.
Take pictures!
https://www.vmaxforum.net/threads/clutch-slave-cylinder-replacement.45011/
This shows you also how to make a simple, inexpensive reverse-bleed tool for the hydraulics, particularly useful for the clutch. Front and rear brakes also benefit from doing a reverse-flush.
That crusty thing with crystallized crud is the clutch slave cylinder, behind the middle side case cover of the engine by the pilot's left footpeg. It has two allen-head screws holding it in place, use a 3/8" allen head socket and a long extension with a ratchet to remove that for cleaning, rebuilding, or replacement.
This is a picture of a SOHC Honda 750-4 front brake, but the crystallized crud is typical of what may await you when you start servicing brakes or the clutch slave cylinder. That stuff was at least 40 years old according to the last registration sticker.
Print this one out in-color, very useful when chasing gremlins.
. Mine's a full power 1990 US import.
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