lol no im good. im already pissed i gotta put this bitch on a dyno. I fsil at carb tuning. fi all day. but this carb ish is a pita.

 

Well, the "lid on but no snorkel" might well be worst of all combinations.
Just an abrupt opening is worse than a well designed snorkel.

I don't agree at all that the stock snorkel is so evil as everyone makes it sound.
Remember, there's a guy who already did a very good experiment.
Best top speed was achieved WITH STOCK SNORKEL. (jetting was corrected for each case)
That doesn't make you one bit curious???

And here we have a PERFECT opportunity to see the facts.
Facts about how it really works. Everything else is just worthless guessing.

If "throwing money away" is the issue, I already said I'll chip in.
If we get the three plots out of this I'll pay the one with lid on and stock snorkel.
IMHO, real "throwing money away" is buying all sorts of parts and just putting on them on the bike without even knowing for sure what the modification did. I much rather spend money on getting the hard facts.

--
Mikko

 

I found his findings interesting as well so i've been doing a bit of my own testing using the butt dyno to try and see the difference between the two.

For reference my bike is stock except for smog delete, screen removed, and a DJ 2152 kit running 3rd clip and 124 main, 2.5 turns out on mixture screws.

With the stock snorkel this setup runs fine, but when i put the KDX snorkel in i got much better throttle response to about 1/3 throttle but some lean surges from 1/3 to 1/2 throttle, from there until WOT seemed ok but felt a little lean.

I really think that in my case i need to drop another clip on the needle and bump the main to at least a 128 with the KDX snorkel. This thing seems to flow alot more air and i really believe there is power there to be unlocked.

I don't want to doubt the validity of the test showing the stock snorkel was "better" but in the back of my mind i still see the jetting issues being a contributing factor. I know i'll be messing with mine a bit more to get the right jetting despite DJ's suggestions for baseline settings. To be fair though, the bike is completely rideable but after all the years i've been tuning carbs i know things aren't quite right.

*edit*

Just re-read my post and it seems to be a bit rambling. Been a bit deep in the "engineering fluid" since putting the bike up for the night.

I guess what i'm trying to say is that how certain was the guy (can't seem to remember what thread the post was in) that his jetting was correct with the KDX snorkel in regards to the main. I don't remember if he talked about changing the needle position either when switching back and forth, though this shouldn't affect WOT top speed performance but i'm just trying to cover all the bases.

 

Seems I've insulted you with my suggestions hence the repeated quoting of throwing money away.

Just remember that there have been many people here for a long time with the same bike that have tried many, many things before you. I'm only suggesting instead of spending your hard earned money trying to figure out how to sneak 1/3 or maybe 1/2 a HP out of these little bikes, you invest it somewhere else is all. Perhaps some slick riding boots, maybe some proper suspension, or hell take your GF/Wife/BF? out for some Chinese.

I'm done with this thread now, so slam away. I'm going to go enjoy what I invested my money in which is 450CC's of badass where a farts worth of air makes absolutely NO difference

Good luck!

 

Finn, I'm not so sure that the snorkel vs. the open airbox on this engine in this bike is a factor for air flow quality. If it was the intake on a ram-air Ninja, probably so. I think the snorkel is strictly a sound reduction shape design. The under-the-seat-pan intake on this bike is practically its own dead air space, so I'm not seeing a snorkel design doing much if anything to contribute to improved air flow. That is speculation on my part. It would be great to see a dyno comparison as you suggest, but the jetting would have to be spot on for each scenario to be a true head-to-head comparison. Interesting stuff.

 

TNC, that's exactly where I'm coming from, too. We all have our own guess regarding what the snorkel does or doesn't do, but very little real data to back up any of it. I know I'm just as likely to be wrong as the next, but I want to know which way it really is.
There's nothing to loose here, correct information is good for everyone.

For sure there is no ram-air effect from a dirt bike snorkel like this. But the sound wave resonances in the airbox do have significant effect. It really isn't about simple question of what flows more air. And what if, just IF, the guys at KHI got their **** right and calculated the snorkel dimensions so that it actually helps the engine. That would be cool to know.

And for Stellar, I not insulted or anything like that at all. Really.
What I was trying to underline with the "throwing money away" quote is that I really think we are often throwing away good money by buying parts for the bikes that are basically just junk.
I'd like to spend little money (1/8 of what a pumper carb would cost) on getting to really see the facts about the air box deal.
It might be just my work, but I think good data is worth a lot.

And the secondly, I don't really care about the peak HP number either. Or getting a fraction of HP more out of the engine. I want to see the torque CURVES. Where's the power-band, how flat the curve is, etc. etc.
If lets say "no airbox cover" is within one cat's whisker better in peak numbers than "stock snorkel" but the stock gives flatter mid-range, I'm going with the stock.

Butt dyno's are easy to fool. A bad flat-spot followed by a peak feels more powerful that flat nice torque curve. Same bike, same dyno, same day type of a test does not lie. Neither does a top speed run.

--
Mikko

 

IG?

sounds just like him

 

Ok ok, lets settle down. Snorkel out gives WAY more mid range. When i took the cover off, it seems like i lost torque. If you look at engineering of a an engine and its intake exhaust paths, a short unrestricted path of the intake system give more power at higher rpms. So if I wanted to jam a filter straight on my carb, i would be better with a kx motor. If you look at every economy car, the intake system is like 4 miles long with all kinds of curves, why? Its driveability. More atomization, more "floating" or "reserved" air volume. So when you open the throttle air is there, like a water jug for a faucet. Now instead of having that volume, you have a filter on your throttle body. Its takes more effort to pull air from the atmosphere, until you reach the engines resonance point and then on to higher rpms. The exhaust is a whole 'nother story. On this application, with stock cams, the best thing you could do is open the snorkel hole. After a set of web cams, 101 grind, snorkel out stock hole is good, race cam, box off.

i run a set of individual throttle bodies on my one civic, it doe lose power somewhat down low and it becomes harder to tune because of the turbulence and lack of atomization. Until you hit higher rpms.

 

sw0, I think your long intake scenario has more to do with a fuel injection application where you want an undisturbed, dead-air space for the sensor that's in the intake runner. And surprisingly there's still a sound issue going on many of these convoluted air intake systems. Two birds with one stone, so-to-speak.

And that issue of using a short clamp-on air filter like a K&N on a motorcycle carb doesn't always work well. It seems fine for most slide/needle carbs, but there are many CV carbs that react oddly with these air filters. Since the slide is drawn by vaccum in the engine and not a mechanical cable or linkage, the tubulent air sometimes caused by these short clamp-on filters can actually affect the way the slide performs.

 

Yes, i agree, also what im basically trying to say is anything past the sork out seems to be a waste of time. When i took the airbox lid out also, it would puddle a bunch of fuel after decel. then when you got on it, it would thump out a cloud of richness. Sucked. and no the long intake term does not apply only to FI, it applies to any flapper throttle system.