Newb here with hesitation issues..

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Maxdude

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I registered for the Vmax forum as soon as I got my vmax last month. Been fun reading the posts and an invaluable resource for me as I go through my new to me bike and get it as perfect as I can. Thanks to this forum I've been able to tackle my dual disc brakes, order the correct gaskets and washers for my left side, select the correct paint to use for my heads, and pick some good tires for it. Now I'm at the point where I need a little help. I went for a ride yesterday and noticed that if in lower gear around 2-4k rpms, when I twisted the throttle just a little bit (like if you were going up a hill and needed more throttle to maintain speed), that the bike hesitated a little and then would accelerate. Almost like a delay or flat spot. Wasnt as noticeable if I opened it up all the way but definitely is there in gears 2-5. I had been running seafoam through my first tank and this was my first ride on a tank without seafoam and I'm thinking that might of richened it up or masked the issue but I'm not smart enough to know that for sure. Dont know what my next step needs to be whether drilling out a/f mixture screw or messing with pilots or looking at air filter or what. Hoping to avoid taking it in somewhere thats for sure. Any thoughts or info would be incredibly helpful and appreciated though, thanks!
 
Here are some questions that will help figure out what the problem might be.

Can you see the A/f screws...or are the brass plugs still in place?

Do you know if the previous owner (PO) put in a jet kit.....or modified the carbs?

Usually a hesitation on the Vmax is a carb issue.
 
Can you see the a/f scews/plugs without taking the faux tank and filter off? I always get the pilot screws and a/f screws mixed up. This link shows the outside of the carbs, and where the chrome plugs are shown in picture mine are missing and open. Is that the a/f screw and same thing you're referring to? http://www.vmaxoutlaw.com/merchandise/performance.htm


Dont think owner did any carb mods and bike has no exhaust mods at all. He was a pretty straight laced guy who rode it and didnt take care of it that well but enjoyed it.
 
The A/F screws.....are also known as the pilot jet screws. You can see the opening for the A/F screws at about 4 oclock in relation to the screw driver in the pic below.

From the link....yes....thats where the A/F screws are.....and its ok if they are open. The ONLY problem with them being open....is that before you start twisting on them, spray some PB blaster inside the opening...and WALK AWAY.....give it a chance to work. Come back about 2 hrs later, and then twist on them.

What the problem....probably is, its time for a procedure called a "shotgun". The pilot jet can get clogged easily....and needs to be flushed out.

http://vmax.lvlhead.com/tips/shotgun.htm

One other question....does it hesitate all of the time, or only if the fan is running....etc?
 

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There is a bottle called "Start your engines", the snake oil I can attest to working awesome. BUT... I highly recommend putting it in before a long day ride and burn off the entire tank of fuel in one sitting. I don't think its a good idea to let the fuel sit with that stuff in it.

I had a bad stumble and flat spot in my 99 right after I bought it. I put a bottle of seafoam through it, nothing, I put a bottle of the "Start your engines" and then for good measure I ran another tank with "Start your engines" in it as well. The bike ran 100% better and the hiccup was completely gone.

Just a thought....
 
I dont know why I thought there was 2 different adjustment screws for some reason one to increase/decrease amount of fuel and one to change the air/fuel mixture. Glad theres only one to worry about makes things easier. Has this flat spot all the time. Runs great otherwise starts up and idles perfect and no other issues anywhere else. I ran when outdoor temps were only 50 degrees and it was doing it the entire 20 mile ride. Good to know about the "start your engines" bottle too Customizedcreations. thanks for the tip I'll try putting some of that in before next big ride where I can run the whole tank in one day. Definitely wouldnt hurt. Thanks for the shotgun link I will give that a try and make sure to shoot some pb blaster in there first. Is that a lot of danger with turning them all a little bit richer would that make things worse? Should I turn just a couple of them richer and see if that fixes it? I'm afraid of making it worse if I twist the wrong one the wrong way the wrong number of times in 1/8 increments. .
 
When my Vmax was "stock" I had the A/F screws anywhere from 3-4 turns out, so turning them out (more fuel....to the left) wont hurt, but probably wont fix the underlying problem.

Here are the stock settings.
Stock A/F mixture settings.
1-2.5
2-2.75
3-1.75
4-2.75

Below is a pic of which cylinder is which.
 

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Regardless of what you do with the carbs, you still should inspect your air filter to determine it's condition, if you do not already know.....sometimes they get a mouse nest up in there which might affect carbs, not to mention plain old dust clogging it up.

Also, if you are going to be playing around with the A/F settings, you might as well hook up a sync gauge and see how close those carbs are sync'ed while you are doing it, as that goes hand in hand with a smooth transition between idle, midrange etc...
 
Regardless of what you do with the carbs, you still should inspect your air filter to determine it's condition, if you do not already know.....sometimes they get a mouse nest up in there which might affect carbs, not to mention plain old dust clogging it up.

Also, if you are going to be playing around with the A/F settings, you might as well hook up a sync gauge and see how close those carbs are sync'ed while you are doing it, as that goes hand in hand with a smooth transition between idle, midrange etc...


Mouse nest, I ll see if I can find my picture of my air box... it was stuffed SOLID. I ran the bike for a test ride and it ran good albeit for the stumble problem. Came back home and spent an hour cleaning the bastard out of mouse shit and thick insulation lol.
 
Thats good idea I should do that, especially considering I had to clean a bee nest out of my radiator when I first got bike :) I'll check the filter and make sure all the important stuff is good and then get to the a/f screws and see if I can steal a sync gauge from a buddy. Turning screws out is that counter clockwise or clockwise looking at side of bike straight on?
 
Well any fastener turning to the left (counter clockwise) is loosening....and turning to the right (clockwise) is tightening.
 
Ok thanks for clarifying. I know the righty tighty lefty loosey thing but wasnt confident enough thats how these were especially cause I just put my mirrors back on and they were opposite threads so wasnt sure. Thanks!
 
Yep....the mirrors are the only thing with a right handed.....and a left handed thread.
 
Spent the day on my max and thought I'd try the recommended shotgun method. Also had a little leak from middle gear gasket, needed dust seal on shifter and also the circlip washer. Also had some weeping from my valve covers from when I changed oil last and discovered I was almost a quart too full. So took care of all that and then pulled everything and blasted away with carb cleaner. Buttoned it a back up and hesitations gone! Some debris or dirt must of got stuck in a jet but I blasted it out and back in business now. So thanks for the help! Glad didn't have to put fluid in or mess with a/f mixture. Last order of business is my brakes pulse badly at low speed especially. Got new tires and new ebc hh brake pads and didn't change at all. Tire shop said rotors were fine off wheel so gonna maybe take it to a brake shop see if they can figure it out.ImageUploadedByTapatalk1430014395.899765.jpg
 
Spent the day on my max and thought I'd try the recommended shotgun method. Also had a little leak from middle gear gasket, needed dust seal on shifter and also the circlip washer. Also had some weeping from my valve covers from when I changed oil last and discovered I was almost a quart too full. So took care of all that and then pulled everything and blasted away with carb cleaner. Buttoned it a back up and hesitations gone! Some debris or dirt must of got stuck in a jet but I blasted it out and back in business now. So thanks for the help! Glad didn't have to put fluid in or mess with a/f mixture. Last order of business is my brakes pulse badly at low speed especially. Got new tires and new ebc hh brake pads and didn't change at all. Tire shop said rotors were fine off wheel so gonna maybe take it to a brake shop see if they can figure it out.View attachment 48823
have you checked your brake rotor buttons? they need to be cleaned or you can get that pulsing problem, google brake button cleaning it's simple
 

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