New member looking for any info i can gather.

[deeps]

Hello all, pleasure to be on the forum.
I have done hours of reading on here and may need some insight on a few things with my max.
Bike is a 99' vmax full power with vboost( still operational) with 4-2 kerkers. K&N filter and other than that bone stock. Just bought a few weeks ago.
Long time enthusiast, new owner of a max, but I am aware of their potential.
Dealing with a lean issue at the moment and from what I can gather and from previous knowledge, my float height is far too lean.
At idle she will heat up above the dot almost to the point of concern and there is almost an "anti-lag" sound between 3700-4000 rpm. If I'm cruising anywhere around that area and snap on it, it does that sound, stutters, hesitates then once at 4500 pulls like a freight train to 9500rpm.
As well it idles decently clean (for a v4) and slow speed maneuvers are without hesitation or back firing.
Plugs are snow white when I take them out.
I've set the A/F to a clean idle, and a tad rich.
I've synchronized the carbs to 22cmhg on all 4. Shotgun cleaned out the air circuits. That didn't work so I have taken the carbs right out, complete and thorough clean, reassembled /installed, synchroed and still lean.
How do I bench set a dry set of floats so I'm at least close. Taking the carbs out and disassembling each time to make minor tweaks to the tang seems like a massive waste of time.
Apologies for the rant. But any insight would be greatly appreciated.
Thanks!

 

[MaxMidnight]

Not sure how you managed to set the balance to a specific value given that #2 carb isn't adjustable (and yes, I know the Service manual gives a spec).
You are aiming to get all carbs at the same value to #2. I would only start to be concerned if the value was significantly different and only then after checking with a different set of gauges.

Can we assume that the intake is OE?

Methinks you need a copy of the Service manual and have a dekko at p5.9 which explains how to check the float level on (or off) the bike with little or no dismantling.
You say the plugs are white, have you done a plug chop and and if so at what revs did you do the chop?

Forgive me if you know this but the mixture will be affected by different systems within the carb dependent on revs.



As far as the Max is concerned you can ignore the throttle slide cutaway.

The first step I would take would be to establish what jets (main and Pilot air jets) and needles are fitted. I'm sure others can advise what jets worked for them with the Kerkers. Use that as a starting point if yours differ from that.
You would need to set the main jet first which you would do by doing a plug chop at full r.p.m. Once you have that optimum then set the needles by the same method and using shims to adjust.
This should get the fueling correct.

BUT....you may be thinking "That's a lot of pratting about to get it right and you would be correct. Not only your time but also money unless you have a supply of jets...

..and those who visit here regularly know what's coming next.

If you want the optimum set-up then get a Dyno baseline run which will tell you exactly what the air/ fuel ratio is throughout the rev range. This will show what needs to be changed and some idea by how much which the Dyno operator should be able to advise.
I don't know how much a baseline run costs nowadays but I suspect it will work out cheaper than the alternative.

 

[deeps]

Thanks @MaxMidnight,
I've read factory spec is 22cmhg for vac, and when I hooked my guages up, the master cyl/ carb being # 2, at a warmed 1000rpm idle was bang on, I then set the following 3 to match.
I have done a plug chop at various stages, like I stated, once past the 4500rpm mark she pulls like nothing I've ever felt, without skipping a beat and the plugs are slightly tanned after a few minutes cruising at 5k~and at 7k~ low end seems to be where my problem is. which would fall under pilot. I would love to send her to the dyno, however I live in a small city and I'm not entirely sure half the population in my city even knows what a dyno is.
I would have to take the bike 6-8 hours to have someone that knows what they're doing.
I went through this same thing with my Maxum, but being a twin, much easier to diagnose and swap jets.
Carbs are on the bench now and I'm pretty certain the mains are 170, and I can't remember the pilots. I think the ones behind the slide cover are 50's but ill have to take them out and put them under the magnifying glass.
My next step will be identifying all jets, writing that down, then setting the fuel bowls 1mm greater for fuel, go another 1/2 turn out on my A/F screws and see how that looks on the plug chop at normal cruising rpm.
I think I'm heading in the right direction but if I'm not let me know.
Thanks again for your input! I appreciate it.

 

[Fire-medic]

Pilot jets need to be totally-clear of any deposits or contaminants. You need to remove 'em and check they are clean. Here's a pilot jet w/a single wire through it to poke-out any crud.




You should be able to see through the pilot jet when it's clear. Any crud in your gas tank and you probably have it obstructing your pilot jets, one or more. 'Shotgun' and the 'peashooter' sometimes work, but if I suspect pilot jets, carburetor removal and disassembly are what to do. Cleaning the tank to shiny-clean on the interior is necessary if you find any deposits or evidence of rust. Don't forget to change the gas filter.

The gas hose which is T-shaped (part #65, below) often breaks on a bike when you're trying to remove the carbs. I suggest having one on-hand before disassembly.





The K&L sets are less-expensive than the OEM parts are are good quality.



The jet block gasket often tears when disassembling carbs to get at the pilot jet. Have 'em on hand before disassembly. Do Not Buy the 'everything' jet/gasket sets on ebay! A waste of $, and not to-spec.



A good parts source: 2007 Yamaha V-MAX (VMX12W1) Carburetor | Ron Ayers

 

[deeps]

Wow so much awesome info, really appreciate it @Fire-medic
Digging in tonight.

 

[Fire-medic]

More: https://dn790009.ca.archive.org/0/i...ice-manual/yamahavmaxvmx12-service-manual.pdf

If you can have access to an ultrasonic cleaner, that's what I recommend for cleaning the carburetors. Separate 'em into left and right pairs, (take lots of pictures) that way you don't have to mess with the throttle and balance screws. If you do use an immersion tank, be sure that you immediately purge any water from the starter enrichment piston system on all four carburetors and also from the coasting enrichment valve assembly diaphragm (part #12, post #4, above and below-this post) on the other side of the carburetor. Be careful if you want to use compressed air on the diaphragm, because you could rupture it, trying to blow it out. Did I mention, take lots of pictures to guide your disassembly/reassembly?

The $$$ issue you may run into from leaving water in them (the starter enrichment system and the coasting enrichment assembly) is that the tiny brass piston will seize in the bore, and you probably will have to get it machined out as trying to remove it yourself and ruining a carb body is an expensive replacement and some bodies are no-longer available new. The replacement diaphragm set for 1 carburetor is $54.

To be clear on currently unavailable OEM parts, look at the potmetal piece between gasket part #17 and screw and washer part #18, 19, which is the body of the choke/starter enrichment system. Unavailable as OEM.

Now look at the potmetal piece between the diaphragm assembly part #12 and the screw part #13, that potmetal cap for the coasting enrichment diaphragm assembly is unavailable OEM. Notice neither of those pieces (the starter enrichment body and the coasting enrichment metal cap) are referenced with even a part number. Take care when working with these pieces!

 

[deeps]

Well I got the max all figured out.
Here is what I did since last chat.
Completely disassembled all 4 carbs including jet blocks, identified and cleaned out all pilots, mains and channels.
Reset bowls for 1mm more fuel.
Set all a/f screws to 3 turns out.
Reassembled and tested. Lean issue on bottom end was gone entirely.(must have been a clogged pilot)
Mid range hesitation was worse. So theory of deduction, must be too much fuel in bowls. Disassembled, again, reset carbs to 28.5 mm as shown in the photos from @Fire-medic . Reassembled, idled and synchronized back to 22cmhg, tested and problem alleviated. I've since Adjusted the A/F screws by ear and to the "plug chop spec" and all look decent.
The max is back gents. She is running strong and the Temps haven't hit the dot yet.(about3/4 of the way to the dot) Over 100km in on premium(91) and so far so good.
The PO kinda screwed things up, put in an exhaust, aftermarket filter, and then went and ran regular fuel, had the A/F screws way more than 3 turns out, and one tip was completely broken off.
Really appreciate the help guys. Made me realize potential issues and aided me greatly. Thanks to @Fire-medic and to @MaxMidnight

 

[Fire-medic]

Glad to hear you found the botched work of the prior owner, or whoever 'serviced' it. FYI, the bike is designed to run on regular gas. Using premium, you don't need to.

FYI, I bought a used bike, and decided to do much servicing on it, and when I got to the cooling system, I found it was filled with crystallized crud from the prior owner, or someone before him. I have pics on an old computer, not set-up, which shows the consistency of it. It was clumping and granular, I suspect that it was two different types of anti-freeze which were incompatible, or maybe some of that 'seal a leaky head-gasket' compound. In any event, I had the heads off, and lapped-in the valves, and had lots of crud I scooped-out of the cyl heads.

deeps, it's always a good idea, after dry-setting the float levels, to do a wet-check of where things are. The service manual has the process.

Page 230 of the 405 pages in the .pdf page count, or chapter 5 (Carburetors) p. 9.

https://dn790009.ca.archive.org/0/i...ice-manual/yamahavmaxvmx12-service-manual.pdf
Again, congratulations on methodically going through things to discover the way to success.