Well I know there has been a lot of talk about this subject, pros and cons and all that, I won't go into all the details of convenience and maintenance and vulnerability and all that jazz but here are my experiences about performance characteristics between the two setups recently using sand mt. utah as a gauge to methodically distinguish what I had originally hoped to use a dyno in Salt Lake City for last week....well the dyno session fell thru for a couple of reasons so I don't have the charts I promised two weeks ago but the mountain is the next best thing and truly is the most fail safe red neck dyno I know of...

first off I show up wearing the long stock intake boot and no airbox - the upgraded rigid one I ordered to replace my old flimsy one on my '01 DS - and I make many runs up and down the valley side of the mountain trial and erroring jetting until I settle on the one that is giving me the most power and highest rpm and shotting up the hill the fastest of course.
7,800 rpm in 3rd gear the whole run after the whoops.
Then I go to the face - 6,500 rpm in 3rd gear the whole way.

then I stick on the carb mount filter, retune to the valley many trial and error runs shooting for the fastest and highest rpm climb, ended up being 5 main jet sizes below what I settled on for the intake boot tuning.
8,000rpm in 3rd the whole run after the whoops.
Then I go to the face - 5,500 rpm in 3rd gear the whole way - she literally fell on her face on the face! Midrange power where you spend alot of time with general duning and bowling was compromised and easily noticed.


So okay the carb mount filter makes better peek power on the top, but loses power in the mid compared to the intake boot setup. I know this is no surprise, this is what I've been told but I wanted to experience the real world impact of course. Seems if all a guy was to do is shoot the same hill over and over and be geared to the rpm where his meat is then the carb mount has a little to be gained, but as soon as conditions change or you go to a different hill or shoot a hill that has a varied grade that does not allow a constant rpm the whole way then there may be much to lose. Not to mention general duning and bowling cater better to a broader power band with midrange being of primary concern. So I went back the intake boot and swapped the jetting back and this is where I stayed from then on.

 

ANNIHILATER recently posted results of his snorkle with a HUGE air filter. I believe with the huge air filter he made more topend.

 

Hightower, are you using the stock carb.

 

donal I am using the TM45

Scooby yes I remember that post, something I may think about adding.

 

i'm probly not the gearhead most of you guys are but on the dyno.. tm 45 no snorkle with uni filter vs. snorkle with K&N . useing the stock snorkle & K&N added 2 hp on hte dyno. just my 2 cents

 

Hightower,

Your findings are consistent with mine[img]i/expressions/face-icon-small-smile.gif[/img]

The way I know that the cons outweigh the pros regarding direct carb mount filters is found in the e.t. from the start of the dyno run to peak power is markedly slower. Even with a little more peak power, You will be late getting to your shift point.............IMHO[img]i/expressions/face-icon-small-wink.gif[/img]

Ron

 

we fitted a DS intake boot and DS filter to my buddy's 450R that day at the mountain too, something KBR in Salt Lake has been doing to their builds....with stock setup and open airbox dyno tuned that day in Salt Lake he could not pull a strong enough 3rd up the valley, but installed the DS boot and filter and jetted accordingly, up 3 main sizes from a 175 to a 182 and he pulled a strong 3rd and picked up quite a few bike lengths. [img]i/expressions/face-icon-small-smile.gif[/img]

 

I put the snorkel on mine this weekend. Chris I want to thank you again for tinkering with my carb. Thumb throttle is a little stiff but not as bad as I imagined. I didn't feel a difference and wondering how do you guys keep your air filter up? I drilled some holes in the plastics and zip tied the end of the filter so it has more support. I may have to play with the dreaded jetting.

 

Entomber I let the snorkel lay on the frame in front of the shock mount, and put a little bitty bungee over it that is attached to the two holes in that flat metal that the exhaust pipe bolts to. the bungee goes from the hole on one side, up and over the intake boot, and to the hole on the other side. basically I'm holding it "down" as apposed to "up". pretty nice of bomb to supply these two holes - don't know what the purpose of them being there is for, they're just there.

and you are welcome on the carb work, my pleasure.

you will need to jet up going from carb mount to intake boot setup. for my particular motor and pipe, there is 5 sizes difference, from 145 with carb mount to 157.5 with intake boot. and from I am told in conversations with THEBOM this is pretty much what he sees to - about 4 or 5 jet sizes difference.
FYI at 5K feet and the weather we had while there I ran 140 carb mount and 152.5 with intake boot...

 

Entomber, how would you rate the pull of the throttle on a 1-10 after Hightower made his mods? Point of reference, lets say stock is a 1. I know I would rate the one on my dads bike at about a 7 or 8 on pull, and just wore my thumb out.