Wires, thats because believe it or not the factory intake system is "tuned" for the engine. When you start taking away the tuned portion then you have to redo the carb. I would like to see dyno numbers on this mod from idle to WOT compared tp stock and see where you lose and where you gain. I would bet that the gain is all at WOT and the lose would be off idle thru mid range. I've done a lot of tinkering with intake systems and exhaust systems on a lot of different motors over the years and have found that the factory will almost always compromise WOT for better performace where the vast majority of your running is done. Just how much time can you spend at WOT with a quad?

 

The Kawasaki 650 was shipped with a bigger intake and larger jets than the Arctic Cat 650. Arctic Cat comes with F/R 122/122 jets, Kawi ships theirs with F/R 138/142. I don't think that Kawi tuned theirs to have less HP.

Majority of the times the intake is tuned restrictive to act as a muffler to reduce noise. My 650 couldn't get above 1/4 throttle with intake opened up, and without jetting it up. Fuel+Air=HP, and that's telling me that anything above 1/4 throttle has more HP, since it needed re-jetting.

Problem with a CVT is you can't really get a decent dyno plot, since you can't get a 1:1 transmission ratio (since the CVT is always changing it).

 

I know all about tuned intakes. A number of years ago(in the earky '80's) Jonhson and Evinrude came out with 6 and 8 hp outboards. You couldn't run then with the air box off at above fast idle or they would die(we put an 8hp on a 8' hydro and wanted it to go faster, had to totally redo both mid range and high speed jets). So I know what you mean, however I would think with a 4X4 quad low and mid range torque would be more important than max HP as they won't tell you what it is unless the law requires it. Beside the tires and suspensions aren't really made for speed either. More max HP gives you higher max speed which isn't really what 4X4 quads are about. It's like hot rod jeeps aren't about high speed but about crossing rough country.

 

As much as possible when riding mud or sand in my experience.

 

Or snow. [img]i/expressions/face-icon-small-smile.gif[/img]

 

Well the snow and mud would be fun except we have real live mountains out here and the roads and trail turn alot. If you don't want to die you slow down and a lot of time don't even get out of 2nd or 3rd gear. Also even the hill are big out here and steep too. So big throttle has limited use.

 

Spoken from someone that doesn't ride a V-Twin. If you had one, you'd find places for WOT. The Kawi V-Twin has more torque than anything I've ever riden (including the 660 Grizzley).

 

Wires; I raced 130 mph boats for years and set several national speed records and was #1 in the nation in my class twice plus more regional and divisional championships than anyone ought to own. So don't talk down to me about going fast, been there and done that long before you were legal to drive. But running a boat on the water on a closed course is on thing and roaring around with a bunch of other helter skelter is another.

 

Hey, Bear, your point may be valid for the smaller atv's used as you describe. But I'll have to disagree with you on this issue with the 650 v-twin. I have about 1,100 miles on mine now a have experienced just what "wires" has explained. I ride from 5,000 11,000 ft. elevation most of the time. My 650 came with the stock 122 jets. With the stock intake and the 122 jets it would start to blubber about 8,000 ft and get real bad at a bit over 10,000 ft. AC recommends a change to 108 jets for this altitude. However, I changed the intake snorkel (to the VDI type - ABS fittings) and rejetted to 140s. Now the bike runs fine from 5,000 to 11,000 ft. (with larger jets) and has noticably more power throughout the range and has improved fuel economy. Agreeably, it is not a huge difference on the bottom end (that's where a module comes in) but it is significant on the mid to top. You don't have to peg the throttle all the time. But I do love knowing that when I want to use the throttle it is there. It will creep along all day or kick out 60 MPH if I am foolish enough to get the urge (which has happened on occasion). Bottom line, the snorkle and rejetting are good for a significant performance improvement. (And by the way, the socket head screws for the float bowls as provided in the VDI kit are a great improvement for access to change the jets - Specially if you use a ball tip hex driver.)

 

All I'm gonna say is this. After doing the intake mod, I went from 12-14 MPG, to over 18 MPG. The next test was at an ATV Pull. I went from almost dead last, to first. My mileage tests were on the same trail, but the second time I rode it, 90% of it was in low range, compared to only about 20% the first time. At the first pull, the only mod was the black EPI secondary spring. I use to have an early Grizzly with 27" Vampires, and I pulled with most of these guys before, and I was pretty competative, so I was able to judge my performance pretty accurately. My AC just wouldn't rev up. It never felt like it got to it's power band. By the time of the next pull, I was able to get the intake mod added. By the way, my wife has had the exact same machines I've had, both the Grizzly's, and now the AC's. Anyway, at this pull, I wasn't able to get her intake moded yet, but she also had the same clutch spring I had. I borrowed a set of 26" MudRunners for hers, thinking I'd give her an advantage in tires, since I had the intake mod. (I was still running the stock tires). I was the only one with full pulls in both the 2WD and 4WD classes. She came in second, about 20' short of my distance, and may I add, she was pi$$ed about that. I'm 6'3', and she's 4'11". On our Grizzlys, she normally beats me by a couple of inches in the 4WD class, and I get her in the 2WD class by a similar margine. I figure it's because with her vertically challanged height, she has more forward weight for the 4WDs, and my longer stance, gives me the advantage in the 2WD with me sitting more toward the rear of the machine. It works out nice this way. Friendly competition, and we both go away with bragging rights. I now have hers moded. Can't wait to see how next years results are gonna be. I would like to see dyno runs too, but I ain't gonna put em back to stock, just to find out. So, I think these two examples would count as good justifications to do the intake mod, wouldn't you?