Parminio gave you good suggestions. His idea of removing the air filter box and using the six-second fuel pump 'pumping' interval with the key being 'on' should show you if you have any issues. It might take two or three on/off cycles to pump enough volume to make any leakage evident, but with a strong light, and maybe a good flashlight to illuminate around the carbs, you should be able to find any evident leakage, or conclude there is no leakage.
About the 'value' gasket set, I'm not sure if Taiwan is the location for K&L kits now. Those look decent, I guess you can try 'em and see how they perform. The
individual single carburetor K&L kits I buy have been printed 'made in Japan,' but I suppose it's possible that K&L has manufacturing in Taiwan too. Do us a favor, take pics of the package, and then compare them to yours. In particular, look at the edge of the jet block gasket of the kit you have, and then the pieces off your bike. Do they appear similar? If you've been wrenching for long-enough, you know that sometimes a gasket will swell from exposure to fuel. One of our members tried the aftermarket 4-in-1 pkg gaskets & brass set and he said that the gaskets swelled significantly, causing issues, and he had to get (I forget which) OEM or the K&L gaskets to replace the ebay crummy set.
Your new tools should allow you to get the carbs rebuilt, saving you considerable $. I believe the $ saved should pay, in one rebuild, for the carburetor tools, themselves.
A reminder, take
lots of pictures to help put things back together. Especially the linkages if you separate the carburetors into four separate pieces, you want to be able to make your effort pay-off with properly-functioning carburetors. I do have a suggestion, about the fuel enrichment assembly (the
fuel enrichment assembly body is no longer available from Yamaha, it's the
not-numbered piece between part #'s 17 and 18, in the fiche diagram below). The
starting enrichment piston needs to be worked to purge any water from the ultrasonic soak!
If you do not do this, the
starting enrichment piston (called the
starter set which is part #20, below) may become frozen in the bore! The stem of the brass
starting enrichment piston is a slim, skinny, shank going up to the brass mushroom head (this is a one-piece, machined assembly) where the brass mushroom head sits above the forked stamped steel piece (the
starter lever). The forked stamped steel piece (the
starter lever) is connected to the rod which is part of the fuel enrichment actuation assembly. See #'s 58 (three pieces, called
starter lever, set 2) and #60 (one piece called
starter lever) in the fiche diagram (link, below). Those are the forked stamped steel pieces which grab the #20
starting enrichment piston assemblies, there are four required #20
starter enrichment piston assemblies.
Usually the number on the fiche to the right of the fiche price for that part tells you how-many of those parts you need
for this page diagram. I am referring to when you use the link below to Ron Ayres Yamaha, to the page for the carburetor exploded diagram. In the example of the
starting enrichment pistons, part #20, called the
starter set, there is only one listed, but there are four required, one for each body. They are all the same configuration/shape. Why it only lists 'the
number of parts of this type required' as only one, I don't know the answer to that. Four carburetors need four #20
starting enrichment pistons (
starter set, as they're called on the fiche).
https://www.ronayers.com/oemparts/a/yam/50045c0ef8700209bc7942f3/carburetor
A reminder:
The '
starter set,' one piece for one carburetor body, four required, for four carburetor bodies. Part #20 on the fiche. Again, I call 'em the
starter enrichment pistons. An example of the
starter set is between the bodies, above, and below. $56 apiece, so it pays to treat them gently, and to ensure that you
purge the starter enrichment casting of any water after using an ultrasonic soak to clean your carburetors. If you simply break them into pairs, leaving the potmetal
starter set/starting enrichment pistons in-place instead of disassembling the carburetors into four separate bodies, you can open the starter set bodies by loosening the hex nuts and draining the piston chambers of any residual water.
If you are removing the
starter set (starter enrichment piston) housing which is the not-numbered die-cast piece no-longer available from Yamaha, between #17 and #18 of the carb body, as-shown in the carburetor exploded diagram-fiche, above, in picture #1, then the carburetors need to be separated into four individual bodies so you can access the starter set die-cast housing, mounting screws. A reminder, to take lots of pictures of each carburetor body disassembly. It's handy to use a piece of paper or masking tape to label each carburetor body as you snap a picture of it. That helps you to put things back together properly.
In picture #2, above, you can see that the top carburetors have their
starter set (starting enrichment pistons) removed, while the lower pair of carburetors has them still in-place on the carb bodies (detail pic, below). Here you can see the hex nut, the round brass rod going to the piston shape (not seen here) inside the
starting enrichment housing screwed to the carburetor body. Directly below the hex nut shape is a rubber cap, and then the forked steel piston lifter which connects via a phillips-head set-screw to the rod which lifts both forked steel piston lifters together on each carburetor pair.
Notes on the starting enrichment pieces:
- in the picture, below, you can see the rod which passes-through the hex nut shape (plumbers would probably refer to the nut as a gland nut) to the starting enrichment piston. Looking at the picture above, you can see the starting enrichment piston is one piece and has a shape of (starting from the right) a narrow short pin, then the piston body, then a thicker round rod, which ends in a shape to accept the individual forked steel piston lifter. Separate pieces are the hex-head, threaded brass nut, the stainless steel spring below it, and the rubber cap above the hex nut.
- if you're careful, you can use a slim wrench to unscrew the hex nut, allowing all the water out, and a few spritzes of WD-40 to purge any remaining water droplets from the casting, and lubrication to permit smooth operation of the starting enrichment mechanism, once it's fully assembled, on each carburetor, and all four carburetors to the starting enrichment lever, This allows you to separate the carbs into two carburetors each, or two pairs of carburetors as seen in the picture #2, above. However, if you want to replace the gasket (part #17 in pic. #1) then you have to break the carbs apart. This is where a lot of pictures taken will allow you to reassemble the carbs properly the first time.
- Having disassembled many VMax racks of carburetors over the years, I have seen some bodges (mistakes) in the 'repairs' done to carbs, and specifically referring to the starter enrichment assembly.
- look at part #63, (the bent bar) which is no-longer available new from Yamaha. This is the malleable rod which connects the starting enrichment circuit mechanisms of the two pairs of carburetors. If you've studied the factory service manual for setting the starting enrichment circuit to properly open and close the starting enrichment system, it mentions bending this arm to make the system work for opening at the same time, both pairs of carburetors. In carburetor racks I've seen, the bent rod has been bent enough that after reassembling the cleaned carbs, the bending of that rod by a prior owner had to be undone. I suspect that sticking pistons in the starting enrichment system were causing the starting enrichment system to not work properly, and that the prior owner bent all-to-hell the rod, trying to make all four pistons operate. Cleaning, lubrication, and proper contouring of the malleable rod so that all four starting enrichment circuits operate together, fixes that problem caused by a former owner.
- I've seen similar issues with the steel forked starter levers (fiche part #'s 58 and 60) where they are bent out of proper shape by a former owner. They required a bit of time to bend them back into proper position so they worked in unison.
I hope this helps you in your repair efforts. Once you're done, maybe post some things you discovered along the way, along with pictures to add to the hive knowledge. I just watched Jason Statham in
The Beekeeper and the hive possesses much unity to achieve a goal.
.
