2005 VMax not wanting to idle

[gimgebow]

Hello fellas,

So I've got a 2005 VMax that sat for a few years in storage. Got it out about a month ago, a friend of my stepdads changed the battery and cleaned out the carbs and plugs. It rides okay, with the occasional backfire and pop after it warms up a bit. Starts just fine.

Problem I'm running into is that it doesn't like to idle without the choke on after it warms up. On the occasions it has idled without choke, it's been sitting around 800rpm and sounds rough, like it's only running on 3 cylinders.
I've cleaned out the carbs extensively, changed out the fuel filter, and tried adjusting what I believe to be the idle screw (phillips with a spring on it between two carbs on left side of the bike). None of it seems to work. It rides fine without the choke, but it will die after a bit if I let it idle. Fella who changed the battery and cleaned the plugs/carbs earlier says he thinks its the carburetor diaphragms, but after some research I'm not really convinced that would fix my issue. I'm not the most knowledgeable about engines, most of what I've worked on is on cars for simple stuff like fuel pumps, brakes, rotors, radiator changes, electrical stuff, etc.
And I've never really worked on a carbureted engine.

Any one of you more knowledgeable folks got any ideas?

 

[Fire-medic]

a 2005 VMax that sat for a few years in storage

The carbs have to be removed, disassembled, and the jet blocks removed, the two brass jets in each removed, and everything ultrasonically cleaned for best results. New float needle jet. The float needle seats rarely go bad unless it's a very high-mileage engine. The gas tank needs to be shiny-clean inside. Unless it's been coated. Cleaning carbs but neglecting a corroded gas tank will just block your carb jets/passages again.

There are many threads about pulling a stored bike out & what needs to be done to make it work properly. Rather than re-write it all, look at the upper-right 'search' button, and use it. I'll start with a few recent threads:

https://www.vmaxforum.net/threads/warp12s-1989-v-max-restoration-3743-miles.51463/#post-518525
Coming out of long term storage. The whole thread, my first contribution I think you will find useful is at #5.

https://www.vmaxforum.net/threads/hi.51624/#post-520431
https://www.vmaxforum.net/threads/got-a-question.50676/
https://www.vmaxforum.net/threads/getting-rust-out-of-gas-tank-without-removing.49639/#post-497010gas tank cleaning. I like 6% vinegar, usually referred to as 'cleaning vinegar.' Home Depot sells 30% vinegar. Dilute it! And do not leave the fuel level sender in the gas tank! I suggest removing the gas tank for best cleaning results. Like Nike: 'just do it.'

OK, those should get you started. Note that there are members on here mentioned in the threads who can do a pro job of rebuilding the carbs, but if you don't inspect, clean, and service the gas tank and the fuel delivery system (carburetors included), you are wasting your $$$.

The factory shop manual. http://vmoa.net/VMX12-Service-Manual01.pdf Print a copy, save this file to your computer.

 

[gimgebow]

The carbs have to be removed, disassembled, and the jet blocks removed, the two brass jets in each removed, and everything ultrasonically cleaned for best results. New float needle jet. The float needle seats rarely go bad unless it's a very high-mileage engine. The gas tank needs to be shiny-clean inside. Unless it's been coated. Cleaning carbs but neglecting a corroded gas tank will just block your carb jets/passages again.

Well, looks like I'll be youtubin some stuff then. I hadn't even thought to check the gas tank, I don't know if it's been coated or not. I figured changing the fuel filter again after a couple miles would help catch alot of the debris that would cause those problems.

 

[MaxMidnight]

As Mr Medic suggests check the fuel tank for any corrosion, that the fuel filter has been changed in living memory and drain the carbs into a clean contaier to see if any crud comes out.
Before wholesale stripping of carbs I would start by running some carb cleaner through the system.
If that doesn't work then try the Shotgun
Only if you are still having problems would I consider an ultrasonic clean.

 

[Fire-medic]

I see that multiple people, you included, have "cleaned out the carbs and plugs." and "cleaned out the carbs extensively." However the issue remains. I suspect it's the carburetors. If they haven't been removed, stripped, soaked (preferably ultrasonically) and blown-out the passages, with a critical eye for wear, failed parts or misadjustments, my opinion is your efforts have been 'for naught,' as our UK friends might phrase it.

A VMax left sitting with fuel in it, especially "for years," and undrained float bowls, before the long-nap, needs the carburetors completely torn-down. No ifs, ands or buts. I don't know if the carburetors were empty when you got it, they probably would be, even if they were not drained because of evaporation and then the carburetors usually end-up looking like this:


Honda Gold Wing carbs not drained before storage.

This is where an ultrasonic soak helps, to loosen and to remove such deposits. Then they come out looking like this:



That's what you need to do. Sure, the peashooter and the shotgun may work for lightly-and/or partially-obstructed carburetor passages and brass jets, but it's akin to cleaning your sparkplugs instead of replacing them. One is a cheap-shot stop-gap method to eke out a bit more miles before you have the $ to do things properly. The other is what should be done in the first place.

Even a few months' storage with the crappy 10% ethanol gas we have now will cause issues. If you ever think you're gonna be off the bike for more-than a couple of weeks, drain the float bowls! 'Two weeks' becomes two months, or longer. You can drain the float bowls and clean-up in less-than 15 minutes, and your carbs will be far-better-off for it, whenever you get back to the bike. The best way to store a bike is carbs dry, and ethanol-free gas in the filled gas tank. That will help the tank to avoid rusting. Even if you have to completely drain the gas tank, and re-fill it before you return to the road after a lengthy delay, the bike will have a much-better chance of the fueling system functioning properly.

Have the carburetors been synchronized since you tried to work on the carbs, or returned the bike to the road? Have the carbs float levels been set?


https://www.ronayers.com/oemparts/a/yam/500456a5f8700209bc79313a/carburetor

 

[02GF74]

What exactly do you mean by "cleaned out the carbs" +

Did you remove the the jet block and jets and made sure the tiny hole in the pilot jet is clear? That usually is the culprit for getting blocked resulting in idling issues.

Re. Plugs, they are cheap enough so why not replace with OEM NGK?

You want to check there is a good spark, the ignition leads can corrode, cutting them back a couple of mm exposes clean copper to establish a good contact.

If you suspect they engine is running on 3 cylinders, then check the temperature of the headers, can do this with an IR thermometer or spray with a tiny amount of water. Hot headers will hiss as the water hits them, cold headers won't = not very accurate but will identify a non firing cylinder.

Finally, have the carbs been balanced?

 

[gimgebow]

As Mr Medic suggests check the fuel tank for any corrosion, that the fuel filter has been changed in living memory and drain the carbs into a clean contaier to see if any crud comes out.
Before wholesale stripping of carbs I would start by running some carb cleaner through the system.
If that doesn't work then try the Shotgun
Only if you are still having problems would I consider an ultrasonic clean.

I ran alot of carb cleaner through the carbs according to this youtube video:

 

[gimgebow]

I see that multiple people, you included, have "cleaned out the carbs and plugs." and "cleaned out the carbs extensively." However the issue remains. I suspect it's the carburetors. If they haven't been removed, stripped, soaked (preferably ultrasonically) and blown-out the passages, with a critical eye for wear, failed parts or misadjustments, my opinion is your efforts have been 'for naught,' as our UK friends might phrase it.

A VMax left sitting with fuel in it, especially "for years," and undrained float bowls, before the long-nap, needs the carburetors completely torn-down. No ifs, ands or buts. I don't know if the carburetors were empty when you got it, they probably would be, even if they were not drained because of evaporation and then the carburetors usually end-up looking like this:

View attachment 85144
Honda Gold Wing carbs not drained before storage.

This is where an ultrasonic soak helps, to loosen and to remove such deposits. Then they come out looking like this:

View attachment 85145View attachment 85146

That's what you need to do. Sure, the peashooter and the shotgun may work for lightly-and/or partially-obstructed carburetor passages and brass jets, but it's akin to cleaning your sparkplugs instead of replacing them. One is a cheap-shot stop-gap method to eke out a bit more miles before you have the $ to do things properly. The other is what should be done in the first place.

Even a few months' storage with the crappy 10% ethanol gas we have now will cause issues. If you ever think you're gonna be off the bike for more-than a couple of weeks, drain the float bowls! 'Two weeks' becomes two months, or longer. You can drain the float bowls and clean-up in less-than 15 minutes, and your carbs will be far-better-off for it, whenever you get back to the bike. The best way to store a bike is carbs dry, and ethanol-free gas in the filled gas tank. That will help the tank to avoid rusting. Even if you have to completely drain the gas tank, and re-fill it before you return to the road after a lengthy delay, the bike will have a much-better chance of the fueling system functioning properly.

Have the carburetors been synchronized since you tried to work on the carbs, or returned the bike to the road? Have the carbs float levels been set?

View attachment 85148View attachment 85149View attachment 85147
https://www.ronayers.com/oemparts/a/yam/500456a5f8700209bc79313a/carburetor

So the carbs don't look anything like that... I'll get a picture up posted today or tomorrow of them. To my untrained eye, they don't seem to have any of the corrosion like the picture above. I have not adjusted the float levels or synchronized the carbs. I'm not sure how to do either of those things, where would I look for video or instructions to do that? The pictures above are kind of hard to read where things are.

 

[gimgebow]

What exactly do you mean by "cleaned out the carbs" +

Did you remove the the jet block and jets and made sure the tiny hole in the pilot jet is clear? That usually is the culprit for getting blocked resulting in idling issues.

Re. Plugs, they are cheap enough so why not replace with OEM NGK?

You want to check there is a good spark, the ignition leads can corrode, cutting them back a couple of mm exposes clean copper to establish a good contact.

If you suspect they engine is running on 3 cylinders, then check the temperature of the headers, can do this with an IR thermometer or spray with a tiny amount of water. Hot headers will hiss as the water hits them, cold headers won't = not very accurate but will identify a non firing cylinder.

Finally, have the carbs been balanced?

Took off the air pods, sprayed a bunch of carb cleaner through the jets and the carbs, let it evaporate before starting it, repeat the process. Just after doing this, it was running mostly okay, just a little rough like it wasn't getting enough fuel for the idle or something.

Yeah, I plan on changing the spark plugs. Not a hard job to do and v cheap, like you said.

The ignition leads seem okay, but I'm not exactly a professional and I've not actually dug into them. I'll check today or tomorrow.

By balanced do you mean synced?

 

[Fire-medic]

'Svnchronized' and 'balanced' are the same thing. An advantage of a single-cylinder bike like the Yamaha SRX: no synchronizing necessary!

Re-read post #2, the last sentence. Your VMax 'bible.' "How do I do it," answers here.

At this point, I'd forget the miracle-cure fuel additives and the magic red wand spraying. Those carburetors have to come-off, they need disassembly, and thorough cleaning of the jet block brass jets. During the disassembly, you can check for mistakes in assembly by a prior owner/'mechanic,' (I've found jet block brass sitting loose in the jet block, behind the rubber plug, either not screwed-in or not properly torqued), ripped CV diaphragms, mis-installed CV diaphragms (I'd like a show of hands, how-many have found the edge of the CV diaphragm not properly-seated in the carb body groove for it?) missing O-rings (the small one beneath the CV diaphragm cover, at the 6 o'clock position may or may-not stay in-place as you remove the CV diaphragm cap), stuck starting enrichener pistons, grossly out of adjustment float levels, flat-spotted rubber tips or worn-out springs on the float needles, plugged pilot jets in the jet blocks (in my experience probably the #1 most-encountered issue in a 'won't idle well' bike, or in a bike sitting for months/years), insufficient slack in the dual throttle cables, causing a 'sticky (won't return) throttle,' dirty fuel filters, dirty air filters, loose clamps on either the air filter box to carburetor bellmouths, or the bottom of the carburetors to the VBoost manifold; and incorrectly replaced/not adjusted carb synch screws.



I'm sure Sean, CaptainKyle, dannymax, and others can name other amateur 'mechanic' trouble-spots in the carb rack they've discovered.

A tip before you tear-into the carburetors, Harbor Freight has an inexpensive set of screwdriver tips, including 'security' tips, where the star-drive has a hole in the middle of the tip, to fit the OEM Yamaha security screws on the CV diaphragm caps. Each cap has one security screw.

https://www.harborfreight.com/security-bit-set-33-pc-68459.html
You can also use a 10" Vise-Grip straight-jaw locking pliers to carefully position the jaws to grip the security screw sides, to loosen it. The third method is to use your Dremel tool and a cut-off abrasive disc, to carefully cut a slot in that security screw's head, and then use a tight-fitting slot screwdriver to remove it. I replace all my phillips screws in the carburetor rack with hex-head cap screws. They're much-easier to use.

What the hey, I'm adding this pilot jet pic, it's been seen before. That's a single strand of stainless steel wire I use to poke out hardened accretions (plugs of debris/gum) which if you have a finger drill (also called a 'pin vise'), holds that nicely. Some people use a guitar string, some a reamer from an oxy/acetylene tip cleaning set. Filching a needle from the ol' lady's sewing kit would probably work, too. The objective is to remove anything preventing the flow of gas. You need to be able to see daylight through that tiny jet.

 

[Aquamax]

Pilot (idle) jets are plugged, simple as that. Although once you are into the float bowls to clean those, it could easily be as nasty as the pics in this thread.

 

[gimgebow]

'Svnchronized' and 'balanced' are the same thing. An advantage of a single-cylinder bike like the Yamaha SRX: no synchronizing necessary!

Re-read post #2, the last sentence. Your VMax 'bible.' "How do I do it," answers here.

At this point, I'd forget the miracle-cure fuel additives and the magic red wand spraying. Those carburetors have to come-off, they need disassembly, and thorough cleaning of the jet block brass jets. During the disassembly, you can check for mistakes in assembly by a prior owner/'mechanic,' (I've found jet block brass sitting loose in the jet block, behind the rubber plug, either not screwed-in or not properly torqued), ripped CV diaphragms, mis-installed CV diaphragms (I'd like a show of hands, how-many have found the edge of the CV diaphragm not properly-seated in the carb body groove for it?) missing O-rings (the small one beneath the CV diaphragm cover, at the 6 o'clock position may or may-not stay in-place as you remove the CV diaphragm cap), stuck starting enrichener pistons, grossly out of adjustment float levels, flat-spotted rubber tips or worn-out springs on the float needles, plugged pilot jets in the jet blocks (in my experience probably the #1 most-encountered issue in a 'won't idle well' bike, or in a bike sitting for months/years), insufficient slack in the dual throttle cables, causing a 'sticky (won't return) throttle,' dirty fuel filters, dirty air filters, loose clamps on either the air filter box to carburetor bellmouths, or the bottom of the carburetors to the VBoost manifold; and incorrectly replaced/not adjusted carb synch screws.

View attachment 85151View attachment 85152

I'm sure Sean, CaptainKyle, dannymax, and others can name other amateur 'mechanic' trouble-spots in the carb rack they've discovered.

A tip before you tear-into the carburetors, Harbor Freight has an inexpensive set of screwdriver tips, including 'security' tips, where the star-drive has a hole in the middle of the tip, to fit the OEM Yamaha security screws on the CV diaphragm caps. Each cap has one security screw.

https://www.harborfreight.com/security-bit-set-33-pc-68459.html
You can also use a 10" Vise-Grip straight-jaw locking pliers to carefully position the jaws to grip the security screw sides, to loosen it. The third method is to use your Dremel tool and a cut-off abrasive disc, to carefully cut a slot in that security screw's head, and then use a tight-fitting slot screwdriver to remove it. I replace all my phillips screws in the carburetor rack with hex-head cap screws. They're much-easier to use.

What the hey, I'm adding this pilot jet pic, it's been seen before. That's a single strand of stainless steel wire I use to poke out hardened accretions (plugs of debris/gum) which if you have a finger drill (also called a 'pin vise'), holds that nicely. Some people use a guitar string, some a reamer from an oxy/acetylene tip cleaning set. Filching a needle from the ol' lady's sewing kit would probably work, too. The objective is to remove anything preventing the flow of gas. You need to be able to see daylight through that tiny jet.

View attachment 85169View attachment 85168

View attachment 85170

Is there a carb rebuild kit you'd recommend, since it looks like I'm going to basically have to replace anything rubber or with a hole in it? Seeing alot on the market, just not sure what fits the VMax or not.

 

[CaptainKyle]

Is there a carb rebuild kit you'd recommend, since it looks like I'm going to basically have to replace anything rubber or with a hole in it? Seeing alot on the market, just not sure what fits the VMax or not.

The only aftermarket kit I will use is K&L and then you will still need the jet block plugs. I have also seen carb cleaner hurt the air cut diaphragms if to much was used .

 

[Fire-medic]

This is the one I buy.



Parts #43 and #45 are the rubber plugs that Kyle is mentioning.



https://www.ronayers.com/oemparts/a/yam/500456a5f8700209bc79313a/carburetor
I like to use Ron Ayres Yamaha.

 

[jamie g]

HERES A VERY DUMB QUESTION SO IM SORRY BUT I WOULD NEED 4 OF THESE REBUILD KITS CORRECT ?

 

[Fire-medic]

Yes.

 

[jamie g]

ok another dumb question if you put the four small k&n filters over carbs do you still need big one to go in between ?? sorry thank you

 

[Fire-medic]

Either/or. Either 4 pods, or one big 'un. You probably will need to fiddle with the jetting if you go to individual pods. The stock internals engine seems to run better when the main jets for the Mikuni carburetors are reduced from the 152.5 mains to 150 or 147.5. A 'richer' engine jetted that-way (with stock 152.5 main jets) will run cooler, where a lean engine tends to run a bit hotter. Dynojet main jets are higher numbers numerically for the same physical size hole/orifice. Use the search function for more info, there are numerous threads on it.

Manufacturers set-up carburetion to be a bit-rich, because there's cooling effect from the extra fuel delivery. That means, less chance of damaging the engine in extreme circumstances, like when an operator is flogging the bike.

The 'lean bikes run better' was very evident with the two-strokes. Because the oil and gas are mixed and the top end (piston, rings, piston pin) and bottom end (crankshaft mains and connecting rod big-end(s) [on a multi-cyl machine] get their lubrication from the oil/gas mixture, any intake leak, like a crankshaft seal, or a carburetor to intake ports on the two-stroke, changes the mixture, leans it out, and usually results in a blown/seized engine. The old adage of the rider of a seized two-stroke: "it was running so-well just before the engine blew!"

 

[Sniffbooger]

I'm no expert, but I'll share my experience with you...I recently bought a non running Vmax, stored for 4-5 years. I had to replace the fuel filter, clean out the clogged fuel pump, and take the carbs apart for cleaning. I bought a carb rebuild kit from ebay, everyone here says they are not good, but I have found good results with it. The diaphragms, screws, gaskets, and even the pilot jets that come with the kit have served me well. My bike currently runs good with the size 40 pilot jets which are a little richer than the stock 37.5s, and the fuel mixture screws are only open about 1/8 turn, and I may put the 37.5's back in eventually, but so far everything has been a good replacement for my carbs, including the gaskets, float needles, diaphragms etc... many of the provided screws are a little too short for the outer parts of the carbs, so I purchased some hex head stainless screws from Sean Morley. For the other parts, I suppose maybe I got lucky and got a good carb kit... I have heard the quality control is the issue with the cheap Chinese made carb kits... but for the most part, it has been a well spent $65...

Take those carbs apart and especially the jet blocks and clean them out! Take a fishing line or a high 'E' guitar string and run it through the jets to clean the holes nicely...it will run better...if it doesn't idle, or has lean popping noises out of the exhaust, its still needing more cleaning...run a few tanks of gas with half a can of Sea Foam through those carbs, eventually they will get cleaned out right!

Jacob

 

[Sniffbooger]

Been working on the bike again today...I'm going to change my opinion about my previous post ..the jet block gaskets in the Chinese carb kit are thicker than the OEM gaskets and they are made of rubber.. I discovered they tend to squeeze out when tightened down and they pinch some of the tiny holes under the jet block almost closed ..this is affecting the way the bike runs...I'm going to order some OEM jet block gaskets ASAP! I'll put the Mikuni 37.5 pilot jets back in while I'm at it ..