modify air box or don't modify air box??

[cals400ex]

after doing some major thinking and contemplating, i came to a few conclusions. i don't think removing the airbox lid is what many claim it to be. i have tested it with it on and off rejetting the bike each time. i think you may gain a little bit of throttle response and some down low with the lid off given the bike is jetted right. however, i don't think the bike is at its full potential up top with the lid off. with the lid off you have tons of volume. i don't think this is what you want. i believe suction will produce the most power. so, i say the velocity is what matters. just think, many times when you decrease the size of your intake ports, you gain power. well thats weird, bigger or more volume doesn't mean better power??? however with the lid on, i don't think you will be getting enough air for a built motor. i need help designing a way i can get more air in than stock but not much more so i don't get too much volume. i want it to suck air. i could be wrong on my thinking, but what do you all think? is this philosophy reasonable or jibber jabber?? any opinions are welcome.

[ghak99]

something to think about! In order for this sucking of air to start there will be a period of wasted time when the cylinder is building vacume. This dead spot or wasted time will probably cost you in throttle responce.
Curious to see what others think

[JOEX]

I agree that the motor will suck in as much air as needed with or with out the lid. Maybe it is easier/more free flowing without the lid? I ran mine for a short while without the lid and with a 160 main. It sounded cool, but I think perfomance was lacking.

Here is a different angle.....

After the last dune trip, with the lid on, there was a couple of tablespoons of sand in the box. The only way in was through the snorkle. I'm thinking of going with one of those EHS/Outerwears type lids and blocking off the snorkle hole will be 'safer' than the stock set up. All air entering the box will be 'pre-filtered' before the actual prefilter on the airfilter.

Joe

[ghak99]

I must say sand is a very nasty thing. I would rather have a quad a little lacking of its full potential than a quad full of sand.

[JOEX]

Originally posted by ghak99
something to think about! In order for this sucking of air to start there will be a period of wasted time when the cylinder is building vacume. This dead spot or wasted time will probably cost you in throttle responce.
Curious to see what others think
This subject came up quite awhile ago with aftermarket boxes that hold the battery and have a lid but I don't think anyone understood it.

What I got out of it is if you fill the box with the battery and put a lid on it you will lose that airspace the intake needs while sucking air. Then what you said, there is a dead spot during acceleration.

Just curious, what is your background/experience in motor work?

Joe

[JOEX]

Originally posted by ghak99
I must say sand is a very nasty thing. I would rather have a quad a little lacking of its full potential than a quad full of sand.
Sand is pretty coarse so i'm not too concerned about it geeting into the motor through the prefilter and filter. That fine dust though..... I have found some in the intake boot.......:(

Joe

[ghak99]

I am not going to lie....I am a 20 year old college student that has had a lot of fun making small block chevys run like crazy. Spent a lot of time playin with anything that runs. Have been through an automotive program and a ford training school.
How about you?

[ghak99]

I forgot to mention I am constantly bored with school and am always thinking of ways to make my toys run faster. I simply go home and apply what is phyisically supposed to work in my mind. Basically trial and error with a college educated guess.

[cals400ex]

i am running one of the outerwear airbox covers and i don't like it. the ones made into the lid i bet are of much better quality. i get so much dirt past the outerwear since it velcros to the box. i think i will be buying a new lid (my lid is already modified) and do some testing with the lid on. i am trying to figure out how my friend with a 406, 10:1 compression wiseco, stage 1 cam, K&N filter with lid ON, big gun slip on, and jetted with a 158 main is ever so close to me when i am running a 406 with ross 10.8 piston, stage 2, modded lid, complete x-6, and jetted with a 160 main. he is even really really close to me on top end. now come on, i am running an x-6, stage 2, and even a 36 rear sprocket where he has stock gearing. his bike is right with me. this is what got me thinking about the velocity of the air versus the volume of air. the only other thing i can try is rejetting. maybe 160 is a bit small. its not like my bike runs bad, his just runs almost as good.

[cals400ex]

Originally posted by ghak99
I forgot to mention I am constantly bored with school and am always thinking of ways to make my toys run faster. I simply go home and apply what is phyisically supposed to work in my mind. Basically trial and error with a college educated guess.

yeah i agree with you. i think about this crap all of the time. some of my thinking actually goes against what you have been taught. prime example is this post. most think removing the airbox will help where here i am saying it may not. i try to think "outside of the box" like mototune (pat) recommends to figure these little tips out.

[ghak99]

I knew that is where you had to get your info from!

The engines he works with are a little different than the typical quad motor.

Those bike don't want a snap of power because that will cause a loss of traction. A quad will handle a snap of power much better and is more desirable.
Just my opinion

[JOEX]

Originally posted by ghak99
I forgot to mention I am constantly bored with school and am always thinking of ways to make my toys run faster. I simply go home and apply what is phyisically supposed to work in my mind. Basically trial and error with a college educated guess.
I have no formal training other tha highschool autoshop almost 20 years ago:p I do have a bit of mechanical inclination (is that even a word!) and quite a bit of common sense and educated guesses as well. And have learned from my many mistakes.

I try to do the trial and error way as much as possible, but that can get expensive when you have other priorities. I did some portwork on a set of Mopar 360 heads a long time ago. The actually grinding is not difficult and they worked fine but knowing what should be ground is what is important. That is what very few people know how to do.

What should work and what really works can be very different!

Joe

[cals400ex]

Originally posted by JOEX


What should work and what really works can be very different!

Joe

i believe this is the key. what should work could be different than what does work best. i will be buying a new airbox lid if they are not too expensive to see if that does anything.

[ghak99]

A multiple cylinder engine is whole new ballgame, every cylinder must match and work as a team. I simple took the automotive porting knowledge and applied it to my 250x. I would love to find a quad set up like mine to put my porting to a test.

Most of the stuff I apply to quad is common secrets in the automotive racing world.

[ghak99]

I will go out on a limb and say that when you put the lid on you will get a slower accelerating quad unless you jet for the decrease in air intake. I would think that if you jet for the open lid box correctly then it will run better than with the lid on.

[JOEX]

Something i'd like to do is get a second or third head and grind each one a bit different then try them out. But that takes time, money and space. Some things never seem to get to line up:(

Joe

[ghak99]

I have a few extra heads and am starting my "so called" testing.
What I need is a professionally done head to use as a performance comparison but that means dollars

[JOEX]

Originally posted by ghak99
I will go out on a limb and say that when you put the lid on you will get a slower accelerating quad unless you jet for the decrease in air intake. I would think that if you jet for the open lid box correctly then it will run better than with the lid on.
I'm assuming you are refering to my comment on the no lid/160 main.....
Where I was riding it at the time was not ideal conditions for it. It was on our home made track that is very tight and fairly low speed (made for the kids) and at about 3000ft elevation. I can take most of the track in third with alot of clutch work and a few spots I can grab fourth briefly. There are lots of humps/jumps and hairpins:p

If it where in a more open area things would probably be different.

Joe

[JOEX]

Originally posted by ghak99
I have a few extra heads and am starting my "so called" testing.
What I need is a professionally done head to use as a performance comparison but that means dollars
You oughta get a 400 with a couple of extra heads to test out for me!:devil: :D

Joe

[ghak99]

I would love to have a 400. But the 400 class around here is full of dumd *** farm kids that love to run you right off the end of the track at ever corner even if you just lapped them....
I think the smaller cc class take more riding talent to win, I always like a challenge

[JOEX]

Originally posted by ghak99
I would love to have a 400. But the 400 class around here is full of dumd *** farm kids that love to run you right off the end of the track at ever corner even if you just lapped them....
I think the smaller cc class take more riding talent to win, I always like a challenge
LOL! I'm thinking about trying flat track (sissy:p ) racing next year.
I'm too old/outta shape for MX/XC:p

Joe

[ghak99]

Flat and tt racing is very popular around here.

[JOEX]

Is that what you do? There is very little mx/xc out here.

Joe

[ghak99]

I race about anything that is close enough to drive to.
I have my own mx track that me and a friend built. It has 3 double a table top and some tight turs with woops in the prosses. Some of the doubles have 25 foot gaps so we even do a little freestyle. I simple like to have all the fun I can....before i get too old to do so

[JOEX]

Enjoy it while you can! The older you get the more it hurts and the longer it take to recover:( Unless of course you stay in shape!:macho

Joe