Raptor 350 mod question
#21
04-18-2007, 11:31 PM
Raptor 350 mod question
Absolutely positively DO NOT EVER buy the drop-in k&n for the raptor 350. To start, they just re-labeled the warrior filter as the one for the raptor. They didn't work that well for the warrior, and it's even worse for the raptor, it doesn't even come close to fitting securely and properly. On top of that, because of the way they are built, the drop-in k&n's start falling apart after the first couple times you wash them. It won't be the same performance either. If you ever had an airbox off of a warrior or raptor, with the filter still in it, and looked into the outlet, you'd see there is at least a half inch of overlap so the airflow becomes turbulent and restricted all in one fell swoop. That overlap also leaves a spot where that foam seal just barely (talking like 2 millimeters on the edge) forms a seal against the box. Yamaha screwed up big on this airbox design back in 1987, and for some reason never did a thing to correct the problem. They probably figured they'd sell more replacement parts this way.
#23
04-19-2007, 01:25 AM
Raptor 350 mod question
I'm not sure if the foam filter that comes with the pro design kit is a brand name uni or not, but truthfully a foam filter is a foam filter, regardless of what brand name is on it it'll perform just the same.
Aside from the differences in maintaining them, it's a lot of speculation and personal opinions, so everyone you ask will say something a little different. Some say that the foam filters can hold more dirt, some say that they filter better, etc etc, but nobody has ever proven it, and i've never seen any evidence of dirt slipping past my k&n. The k&n is also going to be a more free-flowing filter because the air only goes through a couple thin layers of cotton fibers, vs the foam filter, which is first a 3/4" layer of coarse foam, and then about 1/2" of finer, more dense foam. Another thing I noticed with the foam filters, which annoyed me, is that it was hard to get your jetting right and keep it right, because every time you clean them they start this little life cycle over, where first they're more restrictive because of all the fresh oil in them, after half an hour or so the excess oil gets pulled through and burned and you're leaner for a while, and then as it begins getting dirty it grandually gets richer and richer again. I never noticed that with my k&n's as much, only when the filter got real dirty it would start getting rich, which you'll get with any filter full of dirt.
Again, i'm not real sure why anybody chooses foam filters, other than just getting their own opinion in their head and going with that.
Aside from the differences in maintaining them, it's a lot of speculation and personal opinions, so everyone you ask will say something a little different. Some say that the foam filters can hold more dirt, some say that they filter better, etc etc, but nobody has ever proven it, and i've never seen any evidence of dirt slipping past my k&n. The k&n is also going to be a more free-flowing filter because the air only goes through a couple thin layers of cotton fibers, vs the foam filter, which is first a 3/4" layer of coarse foam, and then about 1/2" of finer, more dense foam. Another thing I noticed with the foam filters, which annoyed me, is that it was hard to get your jetting right and keep it right, because every time you clean them they start this little life cycle over, where first they're more restrictive because of all the fresh oil in them, after half an hour or so the excess oil gets pulled through and burned and you're leaner for a while, and then as it begins getting dirty it grandually gets richer and richer again. I never noticed that with my k&n's as much, only when the filter got real dirty it would start getting rich, which you'll get with any filter full of dirt.
Again, i'm not real sure why anybody chooses foam filters, other than just getting their own opinion in their head and going with that.
#25
04-19-2007, 01:43 AM
Raptor 350 mod question
It can get pretty involved, but basically jetting is about shooting for the optimal air to fuel ratio that goes into your engine.
If it's too rich that means there's too much fuel (or not enough air), with that you get sluggish performance and carbon buildup, as well as it running rougher and sometimes hesitating when you hit the throttle.
Being too lean is the one you really have to watch out for though. Leaner (less fuel, more air) is faster (to a certain point) and is a cleaner burn, but it also creates a lot more heat. A machine that's too lean can start burning valves, melting pistons, seizing rings, and all that bad stuff.
That's why you have to rejet if you remove the airbox lid. You're allowing more air to flow into your engine, but the amount of fuel stays the same. Which means it'll be running leaner. So we replace the jet (which is a small threaded fitting with a hole in it to limit fuel flow). Put in a jet with a larger hole, and it'll richen the fuel mixture back up. The trial and error part can be finding exactly which jet you need to get that optimal a/f ratio. (then of course to make it more confusing, there's also different jets in your carburetor for different throttle positions) But that covers the basics for a newbie.
If it's too rich that means there's too much fuel (or not enough air), with that you get sluggish performance and carbon buildup, as well as it running rougher and sometimes hesitating when you hit the throttle.
Being too lean is the one you really have to watch out for though. Leaner (less fuel, more air) is faster (to a certain point) and is a cleaner burn, but it also creates a lot more heat. A machine that's too lean can start burning valves, melting pistons, seizing rings, and all that bad stuff.
That's why you have to rejet if you remove the airbox lid. You're allowing more air to flow into your engine, but the amount of fuel stays the same. Which means it'll be running leaner. So we replace the jet (which is a small threaded fitting with a hole in it to limit fuel flow). Put in a jet with a larger hole, and it'll richen the fuel mixture back up. The trial and error part can be finding exactly which jet you need to get that optimal a/f ratio. (then of course to make it more confusing, there's also different jets in your carburetor for different throttle positions) But that covers the basics for a newbie.
#27
04-19-2007, 09:47 PM
Raptor 350 mod question
Originally posted by: recon99
I'm not sure if the foam filter that comes with the pro design kit is a brand name uni or not, but truthfully a foam filter is a foam filter, regardless of what brand name is on it it'll perform just the same.
Aside from the differences in maintaining them, it's a lot of speculation and personal opinions, so everyone you ask will say something a little different. Some say that the foam filters can hold more dirt, some say that they filter better, etc etc, but nobody has ever proven it, and i've never seen any evidence of dirt slipping past my k&n. The k&n is also going to be a more free-flowing filter because the air only goes through a couple thin layers of cotton fibers, vs the foam filter, which is first a 3/4" layer of coarse foam, and then about 1/2" of finer, more dense foam. Another thing I noticed with the foam filters, which annoyed me, is that it was hard to get your jetting right and keep it right, because every time you clean them they start this little life cycle over, where first they're more restrictive because of all the fresh oil in them, after half an hour or so the excess oil gets pulled through and burned and you're leaner for a while, and then as it begins getting dirty it grandually gets richer and richer again. I never noticed that with my k&n's as much, only when the filter got real dirty it would start getting rich, which you'll get with any filter full of dirt.
Again, i'm not real sure why anybody chooses foam filters, other than just getting their own opinion in their head and going with that.
I'm not sure if the foam filter that comes with the pro design kit is a brand name uni or not, but truthfully a foam filter is a foam filter, regardless of what brand name is on it it'll perform just the same.
Aside from the differences in maintaining them, it's a lot of speculation and personal opinions, so everyone you ask will say something a little different. Some say that the foam filters can hold more dirt, some say that they filter better, etc etc, but nobody has ever proven it, and i've never seen any evidence of dirt slipping past my k&n. The k&n is also going to be a more free-flowing filter because the air only goes through a couple thin layers of cotton fibers, vs the foam filter, which is first a 3/4" layer of coarse foam, and then about 1/2" of finer, more dense foam. Another thing I noticed with the foam filters, which annoyed me, is that it was hard to get your jetting right and keep it right, because every time you clean them they start this little life cycle over, where first they're more restrictive because of all the fresh oil in them, after half an hour or so the excess oil gets pulled through and burned and you're leaner for a while, and then as it begins getting dirty it grandually gets richer and richer again. I never noticed that with my k&n's as much, only when the filter got real dirty it would start getting rich, which you'll get with any filter full of dirt.
Again, i'm not real sure why anybody chooses foam filters, other than just getting their own opinion in their head and going with that.
I do agree with what you are saying and think k&n filters are awesome. I run a open air fliter setup and still ride in dusty and dirty conditions just really never through mud or water. I've always felt like that a foam filter with oil will filter better then a k&n type (this is only my opinion, also a foam filter will not reject water like a k&n with an outerwear). The k&n though will out flow the smurf out of a foam type and it's not even close that's a proven fact as in school we did a test on both of them on a flowbench. Huge difference. I've always seen fourwheelers stock set up with a foam type from the factory, where or not it's because they filter better or not I don't really know other then the fact they just might be cheaper...
#28
04-23-2007, 01:25 AM
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