Im not trying to be a pain in the a$$. But bike is stock in every other way and when jon from ufo talked with me he agreed that it would be lean and told me to trick the servo and see if the popping gos away. When you trick the servo on the vboost it causes a richer fuel mixture. And the popping did go away. I just dont have air fuel adjustment. So i would think if you are correct i should be able to plug servo back in and put a high flow airfilter on the bike and lean the air fuel mixture. Because bike should have adjustment at this time. I tryed pulling air filter and put lid back on without filter before i called jon and no change no air fuel adjustment. Also if i go out to my bike thats running rich (poss) and spray carb spray across the air filter while its running the bike shouldent like it correct.
2004 With Modified Stock Exhaust
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I went out to the garage and thougt about whats going on inside the motor and i felt that the jets are sized and will only let so much fuel flow. i also know that a motor has an intake valve and an exhaust valve that open and close at differnt times. at this point i said to myself dyno's dont lie. so i called a guy i found in the phone book DYNO POWER RACING (dyno-power.com). He agree's the bike would be lean if you open the exhaust. I told him what we talked about as far as the bike being rich and i told him what i had going on in my head and he said that all the vaccum side of the fuel is on intake stroke only. Than the valve closes and we all know what happens when it sparks. at that point the exhaust valve opens and the muffler that is tuned for back pressure is now flowing with less back pressure. So bike can handle more fuel and is now lean. If you make the opening smaller the back pessure for the tuned muffler will go up and engine will go rich. I set up a time to meet with him on 9-2-11 to dyno- tune for $195. I hope this is a good thing for me. I feel good about it. and we will se if i can pull good resalt from drilling out stock deflecter plate that is 10 inch'e up inside of stock muffler. thanks for your input sorry i dont agree. We will see what the dyno tells us. I could be wrong and the dyno will tell me if i am.
one2dmax
Well-Known Member
I've got lots of dyno pulls available if you want to download the reader.
You need to look up a phenomenon on called exhaust gas reversion and scavenging. The harder the pull on the exhaust side of the valve the clearer the cylinder is on it's next intake stroke. This allows for more fuel/air to be taken in since there is lest left over burnt gasses from the previous cycle.
In many engines what you are saying is correct that you will lean out with better exhaust. But most of the time you aren't working with a vacuum slide carb and restricted (as much) air intake flow.
Richening up the mixture by opening up the vboost can simply mask other problems at the cost of potential power and economy.
You need to look up a phenomenon on called exhaust gas reversion and scavenging. The harder the pull on the exhaust side of the valve the clearer the cylinder is on it's next intake stroke. This allows for more fuel/air to be taken in since there is lest left over burnt gasses from the previous cycle.
In many engines what you are saying is correct that you will lean out with better exhaust. But most of the time you aren't working with a vacuum slide carb and restricted (as much) air intake flow.
Richening up the mixture by opening up the vboost can simply mask other problems at the cost of potential power and economy.
Thats why im going to a dyno man. Im not saying u-r wrong. I just diss agree with the bike being rich do to what i have done to my exhaust. I feel you are correct about clearing the cyclinder. 45mpg pulling 2nd 3rd gear rolling hole shots in alot of stright aways on m-22 near suttons bay michigan is ok with me.
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ninjaneer
Well-Known Member
just my two cents, i by far should not be saying anything, i truly am a novice and only have a slight grasp on the carburetor basics, but this i will say, you're not the first to have punched holes in the stock exhaust. whereas some haven't found the need to alter the A/F mixture nor rejetting after punching holes, there are some like myself who, in what i gained in sound, lost half in performance. for me i have no numbers, just feel. and i managed to regain the loss by following the advice of the likes of morley and the other leading experts on this forum, which turned out to be leaning out the A/F mixture--i.e. the hole mod made the bike rich. it will be very interesting to see your results. in the end, i hope you get what your after so that you are on the road that much sooner reaping the rapture of being Maxxed. 
Im riding it the way it is. Im on the road today. I dident drill five hole's in the end of the muffler (dident like that sound) I drilled a 1' hole through the deflector plate that is ten inch's up inside of the the muffler. sounds like ufo exhaust but not as loud. ufo has bigger pipes and more performance potental. dyno power said not to worry about hurting the bike the way it is.
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Rusty McNeil
Well-Known Member
Here's my expeirence with opening up the vboost full time, this is backed up by a permanently mounted wideband air fuel guage.
A carb is a venturi driven thing.
The faster the flow the greater the suction created to pull fuel through the jets. The faster the flow the more fuel is pulled out in to the intake stream.
An engine is a positive displacement air pump, it is going to move a fixed amount of air no matter what you do to it, exhaust and intake changes only change the amount of vaccum or pressure in these areas as the engine moves air, admittedly changing the density of the air entering the combustion cycle, but not to a huge degree.
Opening up both carbs to an intake stroke only slows down the velocity of the air through the carbs, since the same amount of air is now flowing through two carbs instead of one carb, since this air is being "sucked on" by the vaccum created between the piston and the slide not as severely then the charge will be slightly more dense. But not times two as compared to one carb.
This slower moving air has less "pull" on the jets and pulls less fuel through each carb; thereby pretty much resulting in about the same a/f ratio charge in a slower slower moving mass of air.
I've seen no significant change in a/f ratio with the vboost open and making no other changes, nor does it seem to make any significant performance difference in my 1/4 mile times.; maybe slightly.,
I tend to call myth on vboost open making it richer......
I will say having it open all the time decreases bottom end throttle response, but not significantly. Seat of the pants tells me that it is stronger in the midrange area where the Vboost is starting to think about opening on a normal Vmax, but I've seen no affect on a/f ratio.....
This is the same principle that would apply to a street rod that has way to big a carb, you can tune it to the correct a/f ratios across the board but the throttle response down low is gonna suck.
A carb is a venturi driven thing.
The faster the flow the greater the suction created to pull fuel through the jets. The faster the flow the more fuel is pulled out in to the intake stream.
An engine is a positive displacement air pump, it is going to move a fixed amount of air no matter what you do to it, exhaust and intake changes only change the amount of vaccum or pressure in these areas as the engine moves air, admittedly changing the density of the air entering the combustion cycle, but not to a huge degree.
Opening up both carbs to an intake stroke only slows down the velocity of the air through the carbs, since the same amount of air is now flowing through two carbs instead of one carb, since this air is being "sucked on" by the vaccum created between the piston and the slide not as severely then the charge will be slightly more dense. But not times two as compared to one carb.
This slower moving air has less "pull" on the jets and pulls less fuel through each carb; thereby pretty much resulting in about the same a/f ratio charge in a slower slower moving mass of air.
I've seen no significant change in a/f ratio with the vboost open and making no other changes, nor does it seem to make any significant performance difference in my 1/4 mile times.; maybe slightly.,
I tend to call myth on vboost open making it richer......
I will say having it open all the time decreases bottom end throttle response, but not significantly. Seat of the pants tells me that it is stronger in the midrange area where the Vboost is starting to think about opening on a normal Vmax, but I've seen no affect on a/f ratio.....
This is the same principle that would apply to a street rod that has way to big a carb, you can tune it to the correct a/f ratios across the board but the throttle response down low is gonna suck.
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I pluged v-boost back in and the dyno run was 115hp at 71 foot pounds. the o2 reading shows lean at cruzing speeds around 4000rpms 1/6 to 1/4 throttle. So the dyno tech is ordering a bigger piolet jet to install. he said that it is fat on top end so we can get a little power out of a k&n air filter. what is the real hp on a stock vmax. I thought it was 120hp. at 75 foot pounds. I still dont see why i cant get an adjustment out of the air fuel mixture scews. I wounder if im turning the right scews. anyone know the location of the screw.
one2dmax
Well-Known Member
You want it to be lean on light loads. This is how you get economy out of it.
Sean
Sean
Bike is still in the shop. Bike needs bigger piolet jets but dealer dont know what type to get. So im waiting on tech to pull the jets and match them up. I looked on line for about 40min and came up with n151.067 type and to go to a #40 the part # is 004-609 and a 42.5 is a oo4610. Anyone know if im correct. Or anyone know who to talk to about this. I found my info on www.sudco.com . But all sudco could do is help me find pics of jets so i looked up vmax piolet jet pics and found one and match it as best as i could.
one2dmax
Well-Known Member
I have 40's and 42.5's on hand. About $15 plus postage. That's for pilot fuel jets anyway - in the jet block. I still say you want to be as lean as the bike will stand without popping otherwise economy will tank!
Its getting 43mpg to 45mpg. If it dont go below 40mpg and runs strong i will be ok with it. I bought this bike because i wanted a hot rod that would dip into the 11's with me on it. You cant beat the deal on my vmax. 116 to 118 hp 72 to 75 pounds of torx. bike looks new and needs nothing. And it gets 40mpg or better. all this for less than $5000. Any how I just talk to dyno power and mark is waiting for the jets to come in. he said that he feels that 42.5 will work out nice. This way we wont need to turn out a/f srew vary far. he also said that k&n air filter will bring everything together. Im hoping for at least 117hp to 120hp (At the rear wheel) and 74 to 78 pounds of torx. At this point all i can do is wait for mark and his dyno test. Just so everyone knows i changed my forum name to vmax-mike.
haha just bustin my friend..
the only dyno sheet i can find is a 116/77 but i believe i did 119/79 at one point. both were run on humid/hot days so around there.
one2dmax
Well-Known Member
The HP is higher then average (110-115) for your mostly stock vmax but the torque is actually low for a stock vmax (high 70's - low 80's).
Sean
Sean
one2dmax
Well-Known Member
By the way, lean makes HP and rich makes torque with all other things equal
one2dmax
Well-Known Member
Yea, the torque is pretty low compared to average. Should be 8-10 higher then that.
