i am dumb. please help? carb issue (i think.)

i have a vf500f. (86)

i've cleaned the hell out of the carbs while still on the bike, NOT about to take them off, they're way too intracate for me. used carb cleaner and sea foam.

the bike runs when you have the choke on. it'll idle this way too, but the rpms bounce slowly. and it works tons better with a funnel as a gas tank than it does with the actual tank. right now the petcock is in a bowl of gas and sea foam soaking overnight. cleaned the hell out of it to see if that'll help.

tried the idle screw, and before i tightened it up, it wouldn't even come close to an idle no matter what.

also, when you have it in an idle, it sounds kind of like it's working against itself some of the time, rather than being a steady idle. very rarely it'll have a small backfire as well.

all of this makes me think that possibly the air/fuel mix is off, or maybe the carbs need to be synced? maybe rebuilt.... but i really have no clue, i'm pretty lacking in the whole fixing motors department. let alone carbs, and especially motorcycles. so don't assume i've tried the obvious shit, i'm flyin by the pants of my dumb ass on the whole situation. (at least i got it to start though!) =]

any suggestions and help would be greatly appreciated.
thank you.

-Alex.

 

I'll say this much - when the carbs are really bad (enough to cause poor running) they must be removed in order to clean them properly. There isn't enough SeaFoam in the world to clean clogged pilot circuit passages. That stuffs needs to flow through to clean, if the circuit is plugged it can't do it's job. Spraying carb cleaner while the carbs are still on the bike probably won't do it either.

My suggestion is to pull the carbs and take them (or send them) to someone who can properly clean and reassemble them. Carbs suck, so I don't knock you for not wanting to mess with them. Here is a How To guide from my site that should help you with getting them off and putting them back on the engine:

Daugherty Motorsports - Motorcycle Suspension Performance and Modification

 

i had mine done in someone else's ultrasonic cleaner bath and it worked like a dream :thumbsup:

 

when i bought my 750 it was doing the same thing, follow the instructions that jamie has on taking the carbs off and on. if you decide to do it yourself be sure to clean out the pilot jet system. its easy to overlook because the adjustment screw for your pilot jet is covered by an aluminum plug that you need to drill out and remove using a sheet metal screw. also dont forget to address any problems you might have with the gas tank and fuel filter. if you have rusty or dirty fuel tank, cleaning the carbs will only work until your carbs gum up again from contamination

 

alright. i'll take the dammed carb off. where do i hook up the carb sync tool? and where are the little screws that you turn. really, i mean, how the hell do you sync carbs? particularly on a vf500f if you know. thanks again for all the help guys.

 

your going to have some fun with this... you might want to start off by finding a repair manual for your bike. it will give you the specific detail and procedures for syncing your carbs along with the rest of your carb cleaning and inspection. as for the syncing, the first step is to get the bike running and warmed up to operating temp. next there is a screw on each cylinder right next to where the carb attaches, remove these screws and install the fittings that come with the carb sync tool.
a suggestion, if the 500 is anything like the 750 you will have to unbolt the thermostat housing from the engine mount to get to the right rear cylinder and you will need an extra long fitting to make life easier.
once your gauges are installed and you have the bike idling, the fun begins... there is a special tool out there that makes it easier to reach your adjustment screws but if you dont have it i suggest wearing some insulated mechanics gloves to block the heat off of the engine, if you look between your cylinders at the bottom of your carbs you will see some adjustment screws and your idle adjustment knob. once again refer to your manual for the order in which you adjust your carbs because if you go out of order it will mess with the settings of other cylinders that are farther down the line on the throttle linkages. on the 750 the front right cylinder is the master cylinder and you adjust the other cylinders to match it, you start with the screw that is next to the idle adjustment knob, this adjusts the front left carb, the other adjustment screws are located between the rear two carbs, adjust the screw on the right first which adjusts the rear right carb, and finally the screw on the left side to adjust the rear left cylinder.
after each adjustment you make twist the throttle a little and let the cylinders settle for a more accurate sync.
also be sure that if you are going to make adjustments to your idle mixture via the pilot jets, do them before you sync the carbs because by changing each cylinders idle mixture you are changing the performance of each individual cylinder which will throw off your sync if each cylinder if firing at a different fuel mixture

i know i just threw a bunch of info your way so if any of it confuses you let me know and ill explain it further, good luck

 

I was gonna channel Squirrelman for a minute but noticed that you're on a gen 2so there is no wrath of the squirrel......... not sure ho to help...I took the easy way out with mine...I bought carbs that worked at a parts yard 180 bucks.......however to make sure if you like your original carbs follow these steps for removal....

1) do NOT remove the aircleaner base...( the big silver thing that holds all four carbs together) if you take it off you WILL break your fuel rails and vaccum tubes when.
2) you remove the carbs slowly and increasing force I used a 2x3 to help pop them loose but dont try to rip the carbs off.
3) do your rebuild

4) when you are readyu to reinstall the carbs DONOT use a hammer of any shape, kind structure. this will cause irrepairable damage to your carbs ie broken metal tabs that cant be fixed..
make sure you have all the sync tools with. you or that they are available cause it sucks trying to do this while running all over the place looking for the right tools.

me personally I would just scrap the ones that are on it and go get a "new set"

 

It's not that bad really. I'd make sure to get the Honda Manual because it outlines everything you need to know about the process.

 

Its his boots. They are leaking air. 100% positive on this. I did mine, exact same problem. I have seen this, exact same problem, and I have helped trouble shoot exact same symptoms.

SQRM will back me on this.

84 bike; needs full choke to start and idle; rpms bounce;

Definitely the carb boots.

 

That certainly could be it, the insulators (I assume that's what you mean by 'boots') are often in bad shape on the early VF's. It's pretty typical for them to have not been replaced. For the price at least you would know they are not the problem.

 

lol. those boots are way trashed. that is so hilarious. i'll get myself some new ones. taking the carbs off was quite easy actually. we'll see when i go to put them back on. thanks again guys. i'll keep you posted.

 

85 vf500f

i'm looking for a carb rebuild kit for my 85vf500f any one know where i can get one


thanks thor

 

I agree. Once a pilot jet (.038) hole is clogged you will be forced to take the float bowl off and get the jet and blow thru it until you see daylight. No other way.
So keep that petcock in the ON position !

 

You don't need a carb rebuild kit . It is NOT LIKE A CAR!!
Just get a new float needle and install that, and make sure you can see daylight through the pilot jet. THATS ALL.

 

1ZIPLOCK2.... I really do not think you should do this repair yourself.

It's OK we can't be everything.

 

wel that is what the Honda shop told me i needed. the bike runs but i have to use the choke to get it going even in warmer weather and then it starts to over heat on the road( yes i changed out the radiator fluid) they told me i could keep riding it this way but it would destroy the carbs and they would have to be replaced( sounds like BS to me)

 

He doesn't need float needles ( 4 @ $80/set) either.....unless his are leaking.

Many leaky float needles just have rust flakes stuck in the area and can be cleaned to work fine.