Yea ...but im talking just without the box the same filter and everything and make a adaptor to hold the rubber boot from the filter to the carb....wouldnt this get rid of the tubulence the no lid created when running without it? Or...with running the filter like this would a big enough jet size not beable to be found? Im pretty sure that i seen oldmanracing post that the lip on the airbox created bad air turbulance into the carb...so thats where the idea with running completely without the box came to me from.

 

Dunerider650 dont take this as a smartarse comment, but since you have it all
apart, you could use some zipties as a temperary holder and try it out.Or as the
saying goes be the guinea pig.Then let us know the results.[img]i/expressions/face-icon-small-happy.gif[/img]

 

lol...yea i guess i could and i prob will sometime this week. When i simply take off my airbox lid it does seem weak on the top end, but when i take lid and tubes off and gaskets and everything she gets better on the top...so im guessing if everythings off it will rip. Ill try it out and let ya guys know how it goes since it seems nobody has tried this on the stock carb before.

 

alright so i had nothing to do just now so i took off my airbox and just ran the filter and intake boot to carb. All i got to say is....more people have to try this, my jetting had to have been off and i was shifting through the gears half again as fast as i was before and i was shifting at 7 thousand rpms and yea she bounced off the rev limiter in the top just like having the airbox and lid on...need to find a larger jet than the 177.5 thats in it now and test some more...

 

This is what I do to prevent water and mud from entering the open lid. Outerwears make a lid cover, especially to fit the DS airbox. It is cheap, and it attaches to the open airbox with Velcro. Water droplets and mud cannot mass thru the pre filter, but the air does, so unless you put the whole bike under water, you don't have problems with running without the lid. I use this "trick" on all the bikes I set up, from Honda, Yamaha, Suzuki, Kawasaki, and the Bombs.

If you do get water into the airbox, it will most likely be from the open intake tubes, and not the open lid with the pre filter on it. Lid or no lid, you still have that problem, with the intake tubes getting water in them, and it ends up in the airbox.

With the lid on, the bike is pulling well, and the A/F mix is right at 13:1 using the stock needle and main jet, but without the lid, it goes way lean, closer to the 16:1 A/F ratio. After the dynojet kit, and the 200 main jet, the A/F ratio goes back down to 14:1. This to me indicates one thing, and that is that without the lid, there is a massive increase in airflow, turbulent flow or not, the motor uses it. There is no other way why the bike would go so lean, if it was not getting more air, and burning it. If the turbulent air was causing poor airflow, the mixture would go richer, since less air will pass thru the carb, but my dyno indicates differently. The motor can breath that air.

The motor can breath that air, my only problem now is getting enough fuel to complement the extra airflow.

At the moment, the bike is pulling well, but I miss 1 to 2 HP right at the top. Without the lid, the midrange is already stronger, that with the lid on, and I am sure that if I get the fuelling right, I will gain that 1 or 2 missing HP, maybe even more.

Then to clear up some things. The stock CV carb DOES NOT need a vacuum in the airbox to fully open the slide. The slide will open fully with a massive vacuum in the airbox, due to the motor sucking all available air out of the carb, slide or airbox, but the motor will have a airflow problem. Just remember this, a wide open carb with a massive vacuum, can flow less air than a carb, half open with good airflow. The slide is actually designed to open with air, flowing thru the carb, and with the right amount of flow, it will open the slide, all the way, with or without airbox vacuum.

If airbox vacuum was required, why are some DS’s running with a direct mount air filter?

Worry about the flow, and not how large the carb opens, as that is very misleading.

It is can be tricky to sort out the new airflow, from not running a airbox, but it is not impossible, and the rewards for getting it right, is better than running a high vacuum setup, like with the lid on.

 

Freez, thanks for posting your reasearch. Now on your end cap, am I understanding correct that you are not running the baffle inside? So it is a 4 or whatever inch pipe with no guts and a 2.5" whatever cap?

 

Freez, where are you setting the needle with the lid off?
Scott

 

Hey freez...if you ever get the chance...it would be nice to see how the ds does in the dyno without the airbox completely. Just had mine out again tonight and it really does seem faster. Might go back to the airbox simply because its very dirty, wet, and muddy at times around here. Do most quads gain running with just a filter and no box? or is it better to have a box and tune the carb for that? what do you think about the no airbox concept.

Another question thats more important is....since my bike gained soooo much more power is it possible that im running lean and thats the reason for this big boost in power? On two strokes they gain power being lean but is that the same on four strokes? it didnt seem to be running any hotter on the esr temp guage and the fan never kicked on once....no backfiring at all just smooth power entire way....im 2600 feet above sea level running a stock pilot jet, 4 turns out air fuel screw, slide drilled to 1/8 inch holes, 177.5main mikuni jet and no airbox with k and n filter?? could i possibly be running lean and could it burn out the piston like it does on two strokes?

 

At the moment, I am running my end cap with the stock perf and packing. I have not removed anything else from the stock exhaust, except the stock end peace/cap.

I believe that if you make and end cap that joins up inside with the stock smaller perf, and repack around it, that you will get better flow.

That might not be practical, so it might be easier just to rip out all the insides from the stock pipe, and install a perf running the whole length of the pipe, and repack it.

The exhaust gasses will pass right thru the pipe, without getting a chance to expand and slow down. Currently the passage inside the exhaust, made to allow the stock baffle to go inside the pipe, is in my opinion slowing down exhaust flow.

Then, needle position is difficult to pin point on the DS. I have had them set up to run from the 1st to the 3rd clip. Each DS seem to like a slightly different setting for the needle. I think this is due to the type of exhaust the bike is running. Main jets also vary between 190 and 195's.

I still need to test the final needle setting on the end cap I made, but it looks like I need to run it on the 1st clip, maybe even leaner. With the clip on 2nd and 3rd position, there is a massive rich condition, at low RPM (2000 to 3000 RPM). The bike does not stutter from this rich condition, so someone riding the bike might never know it, but the HP is down. If I can sort that out, the bike will give you a bigger kick in the butt, when you let rip from low RPM.

Guys, please keep in mind that I am at 5000 ft, so the setting I come up with, might not work for you

 

Ahhhh it makes sense now. The perf core is tapered from inlet to outlet. I forgot about that. Sorry for being dumb. When I made my end cap, it goes in about an inch and tapers from the perf core to the outlet diameter. I figured it would help flow. No idea if it did or not. Never dynoed it. I see what you are saying now.

One thing we found on the dyno with sleds was a big silencer or can with a small outlet made the same power as a silencer with the same outlet as inlet size. Both made the same power. What we found out was the big silencer was filling with exhaust and "bleeding off" through the small hole while the piston was going up and down on non power strokes not making exhaust. I think that is how they make street bikes so quiet. Don't know if it matters or not. Just food for thought.