Carbs clean and rebuild - ColtMax's 1997 Restoration thread #10

[ColtMax]

This thread is part of a series, you can find the list of all other threads related to my overall restoration here: ColtMax's 1997 Restoration thread

DISASSEMBLY
Time to open up and clean those Carbs! I am always amazed how easy and quick it is to pull the carbs out on the Vmax. One could expect to be much more complex, but it all boils down to:
- Drain the fuel from each carb using the drain screw and tube
- Remove Air box

- 2 Philips screw holding the carb's bowl vent pipes to each side of the Air Box​

- 4 clamps to be loosen​

- The crank case breather pipe to be unplugged (you may want to remove the coolant overflow reservoir to gain proper access to this pipe)​

- Disconnect fuel line
- Disconnect throttle cables from the cable connector box
- Loosen the clamps securing the carb boots
- Pull up, slide to the left and Voilà!

I suggest you take plenty of pictures of the carbs all assemble, this might be quite useful when re-assembling.
Get yourself some magnetic trays, cooking pans, small pill containers or anything that might help identifying, keeping and storing. You may find things needing to be replaced that will make this a much longer project than anticipated.



Now its time to separate this monster of assembly. Using a sharpie and painters tape, ID the carbs with their corresponding cylinder number. Remember the "N" pattern with starting point being Cyl.#1.
I did not take enough picture of this part, I think I might regret it, but one thing to be careful about is to not drop that spring circled in red. And be careful when disconnecting the choke connecting rod between Cyl. 2 and 4.


Once the four carbs are apart I strongly recommend you disassemble and rebuild one at the time. This will give you the opportunity to refer to the ones still assembled in case of memory failure
I have used the Clymer shop manual and the Yamaha factory service manual as my source for info. And this Awesome Forum too of course!

A lot of dirt and gasoline turned into varnish came out while taking them apart. I was surprised to see so much of it. This bike was never stored for period longer than 6 months at the time (winter). Fuel Stabilizer was added to the tank at every last ride of the season, and yet, lots of varnish compound.

 

[ColtMax]

CLEANING
Every part of each carb is placed on a cooking pan and I cleaned them in my ultrasonic cleaner. (one of the best purchase I did, love that thing.)
I have used this home made ultrasonic cleaning solution recipe that is compatible and safe for aluminum components. I did try a mix of Mr.Clean and Water in the past and it would eat through aluminum pretty bad. Make sure to use a cleaning solution that is compatible with Alu.
6-7 minutes with solution at 50C cleaned them pretty good. I have used a soft brush to remove stubborn greasy spots.


I have ordered the K&L carb rebuild kits from ebay (I took the blue packaging individual carb version as suggested by members from this forum)

 

[ColtMax]

INSPECTION
After posting some pictures on a FB group, I was told by (Jon Harris I am sure he is on here too) that my Carbs have been played with:
- Hex Screws on the slider covers
- Pan bolts of the bowls
- Aftermarket needle installed

Surprise! It turns out that my Vmax has always been equipped with a Carb kit from Factory Pro. I assume my carbs are equipped with their kit #1.0 "Supersport kits".
I cant believe this bike has been in the family for 23 years without me knowing this.... The sticker on the airbox kind of gives it away, but I always thought this was simply related to the K$N filter in there. This kit does not required re-drilling and has similar spring length as stock I think.


It is mentioned on Factory Pro's website that the recommended float height adjustment distance is 28.5mm. Mine are currently much more like the 27mm example from this picture taken from FP's site:

My Vmax has a lot of mileage, still running strong, but I thought it was normal to a point to only have 175-200 km of city/cruising range before fuel reserve would hit. Perhaps its running on the rich side.

Here are the old plugs that I replaced lately after taking possession of the bike. I thought they were showing lean condition. That might also be caused by damaged carb and vboost boots which I am also replacing as part of this refresh.
Order: 1 - 2 - 3 - 4


So I think I will readjust the floats per recommendation, change the carb/vboost boots and see from that point how the bike runs next spring.
What do you guys think?

 

[Fire-medic]

Thanks for a thorough set of instructions, and emphasizing that you need to save parts in well-labelled containers, with pictures of everything to help during reassembly.

The springs for the cables in the bellcrank mechanism can 'run & hide' if you're not careful. As you mentioned, keep an eye on 'em.

Anyone doing this should be very-careful about the nylon box for attaching the throttle cables, as it's no-longer listed as an available part on Yamaha's fiche. Those tiny screws holding on the nylon box lid are another 'run & hide' item, if you drop 'em they will be very difficult to locate, unless you work in a 'clean-room.' You can always try dropping another small item, not part of the carburetors, like a small random nut or machine screw and repeat: "brother, brother, go find another!" If you're working on this outside, in the open, you might want to spread a dropcloth and roll the bike into the middle of it, to give yourself a fighting chance of finding something you dropped.

I sometimes use baling wire to string things together in their order of assembly, and to keep 'em together. It helps with orientation of things too, so you avoid turning a 'one-way' piece in the wrong direction upon re-assembly.

I guess it can't hurt to replace the two sets of four boots, but they often develop surface cracks which don't go all the way through. I think you could make a simple pair of metal pieces, just flat stock, maybe 1/8" steel stock, or larger, a couple inches larger in diameter than either of the boots' diameters. Draw a circle on the sheet stock concentric with the rubber boots' center. Outside of that drawn ring, drill 4 small holes 90 degrees apart, in both discs. The holes should be a bit outside of the external diameter of the boots.

Buy a threaded wheel inflation valve, and be sure to have a pair of rubber gaskets for it, and a flat washer which is a bit larger in diameter than the valve stem.

In one of the metal discs, drill a hole to just clear the valve stem diameter. Place the valve stem in that hole and on the side closest to the threaded end. Now you'll have rubber washers on both sides of the metal plate. Place the second flat washer onto the stem, and then the stem hex-nut. Snug it up, this needs to be an air-tight piece.

Now get 4 machine screws slightly longer than the height of the rubber boots. You're going to make a 'sandwich' of one metal disc, the rubber boot, and another metal disc. Place the machine screws into the four holes on each disc, with the valve stem on the outside. Run down machine screw nuts to tighten them so the rubber donut between the metal discs is now an air-tight chamber.

Use a bicycle pump to put a bit of pressure into the assembly and see if you hear any air escaping. If you don't, this shows the donuts don't need replacement. Repeat for the other three.



FP= Factory Pro

1= Dynojet Stage 1
7= Dynojet Stage 7



dannymax's cheat-sheet for float level setting. Look for the die-cast ring/circle on the jet block, the float level should just touch the top of the ring/circle. I see you used it, here it is big for anyone with baby-boomer eyesight.

About your mileage, I have a stock internals, DJ Stage 7 kit, and I usually get ~93 miles, roughly 150 km until reserve. I don't think your report of your mileage is excessive fuel consumption. I do ride enthusiastically, and I see the red-eye winking back at me.